Modular Design for a Product Family of Aesthetic Medical Laser Devices

Modular design for a product family of aesthetic medical laser devices

MAXI SCHUBERT

Master of Science Thesis Stockholm, Sweden 2016

Modular design for a product family of aesthetic medical laser devices

Maxi Schubert

Master of Science Thesis MMK 2017:195 IDE 258 KTH Integrated Product design Machine Design SE-100 44 STOCKHOLM

Examensarbete MMK 2017:195 IDE 258

Modular design for a product family of aesthetic medical laser devices

Maxi Schubert

Godkänt Examinator Handledare 2017-10-24 Claes Tisell Claes Tisell Uppdragsgivare Kontaktperson Asclepion Laser Technologies Thomas Unger GmbH Sammanfattning Denna uppsats beskriver den produktutvecklingsprocess som genomförts i samarbete med “Asclepion Laser Technologies” i syfte att ta fram ett gemensamt formspråk för en produktfamilj av medicinska lasrar. Eftersom att dessa produkter varierar i storlek såväl som utvecklingsår fanns stora skillnader i deras respektive formspråk. Eftersom att formspråk och design är viktiga för varumärkets identitet så eftersträvade företaget att införa ett gemensamt formspråk för sina produkter.

Examensarbetets syfte var sålunda att ta fram en design för nya kåpor. För att göra designen applicerbar över hela produktfamiljen så eftersträvades ett modulärt system. Genom att nyttja samma kåpor till flera produkter kan dessutom produktionskostnad, verktygskostnad och antal underleverantörer sänkas. Varmforming som preliminär tillverkningsmetod bidrar även det till en låg produktionskostnad.

Arbetet omfattade hela produktutvecklingsprocessen i fyra steg, med förstudie, idégenerering, konceptutveckling och produktionsklart koncept. Användandet av metoder och verktyg för utvecklingsprocessen, såsom observationsstudier morfologisk idégenerering, beskrivs övergripande.

I samarbete med en varmformningsspecialist levererades en produktionsklar CAD-modell. Efter att ha reviderats av ett kommersiellt designföretag har den framtagna designen satts i serieproduktion.

Nyckelord: produktutveckling, modularisering, varmformning, produktfamilj, varumärkes-DNA

Master of Science Thesis MMK 2017:195 IDE 258

Modular design for a product family of aesthetic medical laser devices

Maxi Schubert

Approved Examiner Supervisor 2017-10-24 Claes Tisell Claes Tisell Commissioner Contact person Asclepion Laser Technologies Thomas Unger GmbH Abstract This thesis covers a product development process carried out at the company “Asclepion Laser Technologies” for a product family of aesthetic medical laser devices. Due to different dimensions and dates of origin, an obvious divergence in the appearance of the present products within the product family had emerged in the company. Since the recognition value of a brand is greatly influenced by its product design the company aspired the development of a uniform design for the whole product family.

For this purpose, the objective of this thesis was the development of a new housing design. A modular design was pursued, to make it applicable for different devices of the same product family. Building multiple devices from the same housing modules reduces the overall production costs by decreasing tooling costs and decreasing the diversity of parts from suppliers. With the use of thermoforming as the predetermined production method, the production costs are kept low in addition.

During the master thesis project, the whole product development process was executed. The present thesis describes the development process in its four different phases, beginning with the pre-studies over ideation, concept development till the development of a final product ready for production. The implementation of suitable methods and tools in this design process, like observational studies and morphological idea generation, is outlined.

In collaboration with a thermoform specialist a CAD-model, ready for production, was delivered. After a revision of the developed product design by a commercial design company the design has been immediately transferred into serial production.

Keywords: product development, modularization, thermoforming, product family, brand DNA

III

IV ACKNOWLEDGEMENT

This thesis was performed at “Asclepion Laser Technologies” in Jena, Germany. I would like to thank Asclepion, for the opportunity to do my Master’s Thesis and for all the support and expertise. Particularly I would like to thank my supervisor at Asclepion, Thomas Unger and the development manager Ingolf Streit for their guidance, support and education during my internship. Furthermore, I would like to thank my supervisor Claes Tisell at KTH for his tutoring and support in every way. Finally, I would like to thank Daniel Bitai from “BWF Thermoform” for the great collaboration and help in the matter of thermoforming.

Maxi Schubert

Jena, August 2016

VI NOMENCLATURE

Here are the Notations and Abbreviations that are used in this Master thesis.

Notations

Symbol Description

A Area (cm²) d Sheet thickness (mm) L Length (cm) r Radius (mm)

Tg Transition temperature (°C)

Tm Melt temperature (°C)

Abbreviations

ABS Acrylonitrile Butadiene Styrene ADR Aerial Draw Ratio CAD Computer Aided Design CNC Computer Numeric Control DIN Deutsche Industrie Norm (German Industry Standard) HDPE High Density Polyethylene HIPS High Impact Polystryrol LDPE Low Density Polyethylene LDR Linear Draw Ratio LED Light-Emitting Diode PET Polyethylene Terephthalate PMMA Polymethyl Methacrylate PP Polypropylene PS Polystyrene PSI Pound per square inch (psi), unit of pressure or of stress PVC Polyvinyl Chloride RAL Colour matching system used in Europe SB Styrene Butadiene TPE Thermoplastic Elastomers

VII

VIII TABLE OF CONTENTS

TABLE OF FIGURES ...... XI TABLE OF TABLES ...... XII 1 INTRODUCTION ...... 1 1.1 Background ...... 1 1.2 Purpose ...... 2 1.3 Delimitations ...... 2 1.4 Methods ...... 3 2 FRAME OF REFERENCE ...... 5 2.1 Thermoforming ...... 5 2.1.1 Process ...... 5 2.1.2 Advantages & Disadvantages ...... 7 2.1.3 Part Design ...... 7 2.1.4 Tool Design ...... 14 2.2 Laser in Dermatology ...... 16 2.2.1 Components of a Laser ...... 17 2.2.2 Mechanisms Laser Treatment of Skin ...... 17 2.2.3 Laser Safety ...... 18 2.3 EMC (Electromagnetic compatibility) ...... 19 3 CONCEPT DEVELOPMENT ...... 21 3.1 Requirement Specifications ...... 21 3.2 Pre-Studies ...... 21 3.2.1 Market Analysis ...... 22 3.2.2 Customer Survey ...... 25 3.2.3 Observational Study ...... 27 3.2.4 Development of Brand DNA ...... 27 3.3 Ideation ...... 28 3.3.1 Brainstorming ...... 29 3.3.2 Morphological Idea Generation ...... 30 3.3.3 Combination and Evaluation of Ideas ...... 31 3.4 Conceptual Phase ...... 33 3.4.1 Concept Generation ...... 33 3.4.2 Modularisation ...... 35 3.4.3 Evaluation & Screening ...... 36

IX 4 FINAL CONCEPT ...... 37 4.1 Geometry ...... 37 4.2 Product Identification ...... 37 4.3 Laser Safety ...... 38 4.4 Modules ...... 39 4.5 Ventilation ...... 40 4.6 Improvements on handles and display ...... 41 5 FINAL PRODUCT ...... 44 5.1 Product Family ...... 44 5.2 Modularity ...... 46 5.3 Design ...... 47 5.3.1 Geometry ...... 47 5.3.2 Ventilation ...... 50 5.3.3 EMC compatible design ...... 51 5.3.4 Laser safety measures ...... 51 5.4 User handling ...... 51 5.5 Assembly/ Disassembly ...... 52 5.6 Materials ...... 53 5.7 Production ...... 54 5.8 Marketing ...... 56 6 DISCUSSION AND CONCLUSION ...... 57 6.1 Discussion ...... 57 6.2 Conclusion ...... 58 7 REFERENCES ...... 59 APPENDIX ...... 61

X TABLE OF FIGURES

Figure 1. Asclepion Logo (Asclepion, 2016) ...... 1 Figure 2. Product family of laser systems for the medical aesthetic market ...... 1 Figure 3. Process plan ...... 3 Figure 4. Shuttle machine (structure and processes) (Klein, 2009, p. 18) ...... 5 Figure 5. Schematic figure of wall thickness variation: cavity vs. plug produced part ...... 8 Figure 6. Linear draw ratio for plug and cavity produced part ...... 10 Figure 7. Draft angle in a plug and cavity mould ...... 11 Figure 8. Undercut and hinged release (Klein, 2009, p. 49) ...... 12 Figure 9. Undercut and slide release (Klein, 2009, p. 49) ...... 12 Figure 10. Mould with vent holes/vacuum holes (Klein, 2009, p. 56)...... 15 Figure 11. Mould cooling (Klein, 2009, p. 57) ...... 16 Figure 12. Thirty-two cavity mould (Klein, 2009, p. 58) ...... 16 Figure 13. Usage of conductive elastomer gaskets (Williams, 2007, p. 393) ...... 20 Figure 14. Usage of beryllium copper finger strip (Williams, 2007, p. 393) ...... 20 Figure 15. Competitor products (Cynosure, Syneron Candela) ...... 22 Figure 16. Competitor products (IDS Lasers, HOYA ConBio) ...... 23 Figure 17. Competitor products (UNION MEDICAL, Lutronic) ...... 23 Figure 18. Competitor products (UNION MEDICAL, Quanta System) ...... 24 Figure 19. Competitor products (Alma Lasers) ...... 24 Figure 20. Survey results: movable display ...... 25 Figure 21. Survey results: ergonomic properties ...... 26 Figure 22. Survey results: operating position...... 26 Figure 23. Microscoping brand DNA chart for Asclepion ...... 28 Figure 24. Mind map: requirements and ideas for new modular housing ...... 29 Figure 25. Morphological chart for modular housing design ...... 31 Figure 26. Selected principal solutions ...... 31 Figure 27. Two favourite ideas ...... 32 Figure 28. Concept 1, rough, in variations ...... 33 Figure 29. Concept 1, detailed ...... 33 Figure 30. Concept 1, left: laser warning lamp and handle; right: ventilation ...... 34 Figure 31. Concept 2 ...... 34 Figure 32. Concept 1, modularisation ...... 35 Figure 33. Concept 2, modularisation ...... 36 Figure 34. Shape of coloured band, different versions ...... 37 Figure 35. Label “MCL31 Dermablate”, different versions ...... 37 Figure 36. Laser warning lamp, different versions ...... 38 Figure 37. Implementation laser warning lamp feature ...... 38 Figure 38. Modules, thermoform able, first draft ...... 39 Figure 39. Ideas ventilation area ...... 40 Figure 40. Ventilation area, improved ...... 41 Figure 41. Final concept, CAD-model ...... 41 Figure 42. Handle, improvement ...... 42 Figure 43. Display, discussed version ...... 42 Figure 44. Display, increased distance ...... 43 Figure 45. Product family, final design ...... 44 Figure 46. Product family, bird's eye view...... 45 Figure 47. Product family, front view ...... 45 Figure 48. Modularity, find common denominator in dimensions ...... 46 Figure 49. Section view, top module ...... 47

XI Figure 50. Ventilation ...... 50 Figure 51. Hand piece supporting arm ...... 52 Figure 52. Polymer mat and top module ...... 53 Figure 53. Dimensioning sheet size ...... 54 Figure 54. Production coloured PMMA band ...... 55

TABLE OF TABLES

Table 1. Input Material Classified by Thickness ...... 9 Table 2. Estimate process tolerances for thermoformed parts (Klein, 2009, p. 51) ...... 14 Table 3. Morphological idea generation, features and corresponding solutions ...... 30

XII 1 INTRODUCTION

This chapter describes the background, the purpose, the delimitations and the methods used in the presented Master Thesis project.

1.1 Background Asclepion Laser Technologies, located in Jena (Germany), develops and produces medical laser technology (Asclepion, 2016). The company has become a leader in the world market by offering not only a product, but a whole service with e.g. trainings for ensuring the success of its distributors and physicians. The Asclepion logo is shown in Figure 1 below.

Figure 1. Asclepion Logo (Asclepion, 2016) The company’s portfolio contains different product lines: laser systems for surgical applications (named “Jena Surgical”), systems for the beauty market (named “The FaceLab”, “The BodyLab”), and laser systems for the medical aesthetic market. With those last named laser devices, treatment for aesthetic medicine like tattoo removal, skin rejuvenation, acne treatment, skin resurfacing or hair removal is possible. The devices associated with this product line are shown in Figure 2 below.

Figure 2. Product family of laser systems for the medical aesthetic market (from left to right: “MeDioStar NeXT PRO”, “MCL31 Dermablate”, “TattooStar” and “QuadroStarPRO”)

1 As stated on the Asclepion website “MeDioStar NeXT PRO” is a high power diode laser and designed specifically for hair removal. It can also be upgraded for vascular treatments, skin rejuvenation and acne treatment. “MCL31 Dermablate”, with an Erbium:YAG laser is created to overcome skin problems: epidermal and dermal lesions, scar treatment, fractional and full skin resurfacing. The “TattooStar”, with Q-switched Ruby and Nd:YAG technology provides excellent results in the removal of tattoos, pigmented lesions, permanent make-up and melasma treatment. With yellow, green or infrared light, the “QuadroStarPRO” is specialized in the treatment of vascular and pigmented lesions, melisma and nail treatment. (Asclepion, 2016)

1.2 Purpose As can be seen above, the existing product family (Figure 2) features a different housing design for each of the laser device. Building multiple devices from the same housing modules would reduce the overall production costs, by decreasing tooling costs and decreasing the diversity of parts from suppliers. With this step of modularisation, a product family design is to be developed in which the company’s identity is reflected.

The objective of this master thesis project is to develop such a modular housing design for the shown product line. The device “QuadroStarPRO” (Figure 2, right picture) is excluded from the project, since it was redesigned and relaunched recently and has a totally different geometrical dimension. Therefore, the modular housing has to be developed for the other three devices.

Thermoforming is the predetermined production method. The modules have to meet the dimensions and functionality of all the different types of stand-alone devices in this product line. With a modular housing, all devices have the same shape and look the same as long as no distinguishing feature, like e.g. colour, is existing. Therefore, the objective is to introduce design features which makes it possible to distinguish between the different types of devices. In order to consider the company’s personality in the design concepts, the brand’s DNA should first be defined.

In the end, the developed modular design should be applied in detail for the new design of the device “TattooStar” (red device in Figure 2). The design has to be modified for thermoforming as the predetermined production method. For the final CAD-model, the focus is therefore on production compatibility. At the end, a production oriented CAD-model of the modular housing for the planned device “TattooStarPICO” will be handed over to the engineering department of Asclepion.

1.3 Delimitations The Master Thesis project covers only the development of a modular design for the housing (skeleton structure) of the laser devices. The housing was designed with regard to the corresponding measurements and requirements of the inside components. The main part of the project was the design of the polymer shell. In addition, a metal case with ventilation holes was designed and assembled with the polymer housing. An assembly with the inner components (like e.g. the laser, the cooling system, the electronic control unit) has not been created. A more detailed assembly of the metal case and polymer housing has only been performed for the device “TattooStarPICO”.

2 1.4 Methods Figure 3 shows the process plan for the master thesis project. In order to understand the company’s identity, extensive research within the company was performed, to be able to develop the brand’s DNA, but also to understand all requirements for the new product. At the start of the project a small customer survey was performed, asking physicians for demands towards special design aspects, in order to understand the customer requirements. Another way of information search included asking employees towards requirements for laser devices and gathering consisting knowledge about design aspects, through e.g. getting an insight to the production and in this way investigating the whole life cycle of the product line. Field studies in form of observation are considered as a good way to understand the user’s needs and potential needs. (Kang & Suto, 2013) This was realized through the participation at a national training, watching the aesthetic-medical-devices in action and observing the physician using the product. Parallel to these background studies, a short market research was performed, to identify competitors on the market. With all these pre-studies the customer needs and the needs of the company were identified. Finally, the Product-Design-Specifications were defined with this knowledge.

Figure 3. Process plan The next stage was the “Idea generation” stage. To develop a product line design, the brand’s DNA was defined, with the help of the tool “Microscoping” described in “Design Thinking for Entrepreneurs and Small Businesses” by Ingle (2013). The objective of this step was to develop a conceptual design proposal for a modular design. The ideas were developed with the help of brainstorming and “morphological idea generation”. Several different concepts were presented to Asclepion, to evaluate and choose the favourite concepts together. Those concepts were illustrated through sketches. In the “Conceptual Phase” the two favourite concepts were visualized through renderings of simplified CAD-models. Those concepts were evaluated afterwards to choose the final concept for the Design Development phase.

In the “Design Development” phase the modularity of the housing was developed and applied to the final concept. A detailed CAD-model was performed. Renderings of different variations in e.g. colour and material were produced for all three laser devices. The final design concept was applied in detail to the device “TattooStar” (red device in Figure 2), resulting in the final CAD model for the polymer housing with the focus on production compatibility. A metal case was modelled in CAD and assembled with the polymer housing. This result has been handed over to the construction department of the company where it is further developed for the production of the device “TattooStarPICO”. The CAD program Solid Edge, in the versions ST7 and ST8, is used for the presented master thesis project.

4 2 FRAME OF REFERENCE

Thermoforming was defined as the desired production method by Asclepion. This chapter presents the thermoforming process and its characteristics which have to be considered during the design process. A short thermoforming design guideline is presented, which is followed later on during part geometry implementation in CAD. For design and planning of a medical laser device, some special requirements have to be considered. Specifications are given for laser safety as well as electromagnetic compatibility of the developed product.

2.1 Thermoforming “Thermoforming is an industrial process in which thermoplastic sheet (or film) is processed into a new shape using heat and pressure.” (Klein, 2009, p. 1)

2.1.1 Process According to Klein (2009), thermoforming is considered a secondary process, as the input materials (plastics sheet and film) must first be created.

Three basic types of thermoforming machines are named by Klein: cut sheet shuttle machines, cut sheet rotary machines, and roll feed continuous machines. The shuttle machine (illustrated in Figure 4) handles only a single cut sheet at a time. The cycle time includes loading, heating, forming, cooling, and unloading in a sequence. Hence this is a slow process and commonly used for low volume or very large products. (Klein, 2009) The following steps are required for the fundamental thermoforming process: . Sheet preparation . Loading sheet into process . Heating sheet to its forming temperature . Stretch sheet into desired shape . Cooling . Unloading part . Trimming part to desired final form (Klein, 2009) The essential process steps will be discussed in the following section, to get to know some important characteristics of the manufacturing method.

Structure Heating Process Forming Process

Figure 4. Shuttle machine (structure and processes) (Klein, 2009, p. 18)

5 Heating: Three methods of heat transfer are used in the thermoforming process: radiation, conduction and convection. According to Klein (2009) radiation is mainly used to heat the sheet to the desired temperature. Through conduction, the core of the sheet is heated. Conduction is important as well in the cooling process, when the sheet contacts the mould. Convection is used primarily to cool the part, with the help of water lines in the mould, so it can be removed from the mould more quickly. Due to the fact that plastics are thermal insulators, it is very difficult to transfer heat into the centre of a thick sheet of plastic. Therefore, thermoforming has a limit on sheet thickness. Thermoforming of plates (sheet thickness above 13mm) requires special expertise and equipment. (Klein, 2009)

Forming: Thermoforming is a stretching process. The properly heated thermoplastic sheet is stretched into a new shape using some type of force. (Klein, 2009)

Different forces can be used to form the sheet: a) Mechanical Force b) Atmospheric pressure (most common): A vacuum is drawn between sheet and mould. This force is quite limited with a maximum force of approximately 15 PSI (~103 kPa). Therefore, it is widely used for high volume thin gauge forming where only minimal pressure is required to stretch the sheet to the desired shape. c) Pressure forming: This may be used when atmospheric pressure is inadequate to form the sheet into the desired shape or detail. In this case, compressed air is used which has a practical limit of about 150 PSI (~1034 kPa) or 10 times the force of vacuum forming. d) Combination of forces: For example, a mechanical force may stretch the sheet followed by a vacuum to draw the sheet into the mould. This is often used to reduce the wall thickness variation. (Klein, 2009)

Cooling: When the sheet contacts the mould surface, cooling begins. The hot plastic material is heating the cold mould (conduction heating). Aluminium is the most commonly used mould material for high volume parts. By passing temperature controlled water through drilled passages, the aluminium mould is cooled. The mould material and part thickness mainly determine the length of the cooling process. Cooling e.g. a roll-fed, thin gauge part on an aluminium mould may take as little as 1 second. On the other hand, cooling a thick gauge sheet of acrylic on an epoxy tool may take several minutes. (Klein, 2009)

Unloading: Timing is important for unloading a part from the machine. On one hand, the produced part may deform while and after removing, if it is not sufficiently cooled. Exaggerated cooling, on the other hand, increases the cycle time and profits suffer. (Klein, 2009) Plastic material shrinks as it cools. This fact makes unloading in a cavity mould easy, since the part shrinks away from the mould. In a plug mould in contrast, the part shrinks onto the mould, creating a tight fit which can be difficult to release. In that case, mechanical or air ejection can help to release the part, as well as providing the maximum draft angle allowable for the product. (Klein, 2009)

6 Trimming: All thermoformed parts must be cut out of the formed sheet. Depending on the desired shape and quality of the end product, this can be done by a simple straight cut, or very complex, requiring a computer guided laser. For thick gauge and lower volume products, chip removal processes are used, including sawing, routing, drilling, water jet and laser cutting. (Klein, 2009)

2.1.2 Advantages & Disadvantages The production method thermoforming has several advantages over other polymer processing methods, like injection moulding or compression moulding. One advantage is the need of a lower forming pressure and with that, the possibility to use simpler moulds from a variety of materials. The low equipment costs and the low tooling costs make the production method cost-saving. Therefore, thermoforming is economical to produce at low volumes. (Klein, 2009) Furthermore, the lead times from design to production are shorter than for other production methods. One important advantage is the opportunity to produce large parts, like refrigerator doors or bath tubes. (Subramanian, 2011) A large surface to thickness ratio is common, which makes it possible to produce very thin parts like disposable drinking cups in thermoforming. Another advantage is the possibility to use multi-layer sheets to produce multi-layered thermoformed products with different qualities united in one product. (Klein, 2009)

Nevertheless, some shortcomings of thermoforming have to be named. The number one disadvantage is the non-uniform wall thickness of the final part. Another crucial disadvantage is the limited part geometry. Furthermore, the single-surface mould creates detail on only one surface of the part. Moreover, the realization of undercuts and hollow objects is difficult to implement and causes extra costs. Thermoforming necessitates also trimming operations after the forming process. The trimmed remnant adds up material costs. Typically, the trimmed material is reclaimed, using grinding and reprocessing methods, which adds more costs to the product. (Klein, 2009)

2.1.3 Part Design The first decision to make in the design process is whether thermoforming is a suitable production method for the desired part design. According to Peter W. Klein (2009) the following questions represent the design issues that need to be considered to answer this question. Most of these aspects will be further discussed in this subchapter, as well as in subchapter 2.1.4 Tool Design.

Design Questions: . “Will the part design allow for the number 1 issue in thermoforming – wall thickness variation? . What material is to be used? . What is the actual part geometry? ▪ Corner radii? ▪ Draft angles? ▪ Depth of draw? ▪ Is webbing a concern? ▪ Are there any undercuts or negative draft angles? . What are the application requirements for this part? ▪ Useful temperature range? ▪ Strength requirements such as pressure, impact, stiffness, etc.? . What are the quality expectations? ▪ Cosmetic? ▪ Optical?

7 . Dimensional tolerances?” (Klein, 2009, p. 35)

Wall thickness variation As mentioned in the first design question above, wall thickness variation is the number one issue in thermoforming. Wall thickness varies with the amount of stretching that occurs. One option to reduce the wall thickness variation is pre-stretching the sheet with pneumatics or a mechanical plug. (Klein, 2009) The amount of variation in wall thickness is highly influences by the part geometry. But also the decision whether to us a plug (male/positive) or cavity (female/negative) mould has a huge impact. The first area of the sheet that touches the mould will be the thickest, since the material quickly cools as it touches the mould surface. This is the reason why an almost inverse relationship in wall thickness between parts of the same geometry appear, when formed in a cavity type mould compared to those formed over a plug type mould. (Klein, 2009) This relationship is illustrated in Figure 5 below. Both tool types are used in the thermoforming industry. With the choice of the tool the thinning location of the material can be influenced.

Figure 5. Schematic figure of wall thickness variation: cavity vs. plug produced part Material and Draw Ratios

Almost any thermoplastic polymer that can be created into a sheet form can be thermoformed. Nevertheless, there are materials that dominate this industry. The following list shows the most used materials in the thermoforming industry. . Polystyrene (PS) . Acrylonitrile Butadiene Styrene (ABS) . Polyvinyl Chloride (PVC) . Polymethyl Methacrylate (PMMA or Acrylic) . High Density Polyethylene (HDPE) . Low Density Polyethylene (LDPE) . Polypropylene (PP) . Cellulosic . Polyethylene Terephthalate (PET) . Green Plastics (Bruder, 2015), (Klein, 2009) The input material can also be classified by material thickness. This classification is shown in Table 1.

8 Table 1. Input Material Classified by Thickness

Material Thickness Classification < 0.25 mm Film/Foil < 1.5 mm Thin gauge > 3 mm Thick gauge > 13 mm Plate

One important variable in the thermoforming process is the type of material to be formed. Different plastics require different amounts of radiant energy to reach the forming temperature. To increase the temperature in crystalline plastics for example, more energy input is required than for amorphous materials. Furthermore this is influenced by the type and amount of ﬁllers, reinforcements and even the colour of the sheet. (Klein, 2009) The degree of crystallinity is quite important for the thermoforming process. Amorphous materials e.g. change gradually when heated. This means they have a wide softening range, which sometimes spans over about 55 degrees Celsius. This gives the thermoformer a lot of processing opportunities. In comparison, crystalline plastics have a sharp melting point (melt temperature Tm). On one hand, no forming can occur until the material is within about 3 to 6 degrees of Tm. If the melt temperature Tm is reached or exceeded during the thermoforming process on the other hand, the sheet will rip or fail in the oven. This means that crystalline materials have a small forming window and tight process control is required. Short before the melt temperature is reached, the crystalline areas break down and become amorphous. This is called the glass transition temperature or Tg. The time required to heat the sheet to the correct forming temperature drives the cycle time of the process (Klein, 2009).

For material selection, not only the compatibility of the material for the end use of the product is important, but also the properties for manufacturing. One question during material selection is whether the material is available in sheet form and at the desired thickness. Furthermore, the draw ratios of the selected material have to be adequate for the application. Several Draw Ratios are mentioned by Klein (2009) to be used to analyse and compare parts. These include Aerial Draw Ratios, Linear Draw Ratios and Height-to-Dimension Ratios.

 Aerial Draw Ratio The Aerial Draw Ratio (ADR) is the overall measurement of the stretch of the sheet. It can be calculated as follows:

퐴푓표푟푚푒푑 퐴퐷푅 = (1) 퐴푢푛푓표푟푚푒푑

Whereas 퐴푓표푟푚푒푑 is the calculated surface area of the formed part and 퐴푢푛푓표푟푚푒푑 is the surface area of the sheet used to form the part. (Klein, 2009)

 Linear Draw Ratio The Linear Draw Ratio (LDR) can be calculated as follows:

푙푎푓푡푒푟 퐿퐷푅 = (2) 푙푏푒푓표푟푒

9 Whereas 푙푏푒푓표푟푒 is the length of a straight line drawn on the sheet, before forming. 푙푎푓푡푒푟 in turn is the length of the same line after forming. Only the forming area of the sheet is included in this calculation. The formed part is typically assessed in the direction of maximum draw. Producing the same part with vacuum forming (and a cavity mould) gives different results than producing the part with drape forming (and a plug mould). In the Vacuum forming process only the sheet area within the cavity opening is reshaped and used to produce the part. Therefore, the sheet must stretch further when using this process. For drape forming, the area within the clamping frame must also be considered as forming area. A bigger sheet area is needed to cover the whole mould. Hence more material for forming is provided and less stretching needs to occur to shape the same part. (Klein, 2009) This difference between parts made with cavity and plug moulds is illustrated in the following Figure 6 and in addition, shown in an example calculation of the LDR parameters for the two different mould options.

Plug Mould & Drape Forming Cavity Mould & Vacuum Forming

Figure 6. Linear draw ratio for plug and cavity produced part On the left side of Figure 6, the production of a part with a plug mould and drape forming is shown. Before forming, the line length is 5 cm and after forming 8 cm. Resultant the LDR = 8/5 = 1.6 or the line is now 160% of its original length. The right side of Figure 6 “illustrates the LDR parameters for a part produced using a cavity mould and the vacuum forming process.” (Klein, 2009, p. 43) Before forming, the line length is 2 cm and after forming 5 cm. Resultant the LDR = 5/2 = 2.5 or the line is now 250% of its original length. This illustrates, that the material is stretched by far more in the cavity mould process than in the plug mould process. Therefore, a thicker polymer sleeve is required for the cavity produced part. A larger sheet area on the other hand is required for the plug produced part. The stretch ability of a material becomes important, considering the above calculated examples. An important question is therefore, whether the draw ratios of the selected material are adequate for this application? Thermoplastic polymers vary highly in their ability to be stretched without failing. The aerial draw ratio of Polystyrene for example is 8.0, which means it can be stretched 8 times its original volume without failing. Acrylic in comparison has an aerial draw ratio of just 3.4. Although both of these materials are commonly thermoformed, polystyrene is more suitable for deep draw parts. (Klein, 2009)

 Height-to-Dimension Ratio The height of the formed part divided by the length of the greatest opening of the part gives the Height-to-Dimension Ratio. The usefulness of this ratio is limited to simple symmetric parts. (Klein, 2009)

Part Geometry and Design Guidelines

Designing a product for thermoforming, the designer has to be aware that the part geometry should meet the thermoforming design guidelines. Some of those guidelines and a couple rules of thumb will be introduced in the following section.

 Corners and Radii: During forming, material must be drawn into inside corners or wrap over outside corners. Corners are stress concentrators in the geometry. The sharper the corner, the thinner and weaker the part will be at that spot. (Klein, 2009) Therefore, the thermoforming guidelines call for the largest radius possible. Peter W. Klein (2009) mentions that the advice for the minimum radius differs from source to source. One source indicates that a minimum radius of 4.8 mm is adequate. The next source gives the suggestion that the radius should be equal to or greater than 3 times the thickness divided by 4.

3푑 푟 ≥ (3) 4

Another source uses a simple formula of 1.5 times the starting sheet thickness. After all these different advices Peter W. Klein draws the conclusion that it is important to realize that a corner will be a weak and high stress point in the part. The best rule to determine the radius of a corner is therefore to make it as large as possible.

 Draft Angles: The draft angle is the angle the mould wall makes with the vertical, like illustrated in Figure 7. If the mould wall is vertical, there is 0 draft. Draft angles are necessary for the process, even if they may be undesirable for the part designer. The importance of the draft angle is different for the cavity versus the plug style mould. When the heated formed sheet cools, it shrinks. In the cavity mould it is shrinking away from the cavity. For the plug mould on the other hand it is shrinking onto the mould and grabbing the plug. For this reason, cavity moulds do not necessarily require any draft although up to 2 degrees is suggested. Plug moulds on the contrary must have draft in order to allow the part to be released. (Klein, 2009)

α – Draft angle

Figure 7. Draft angle in a plug and cavity mould

11  Depth of Draw: Like explained earlier, the decision whether to use a plug or cavity mould has a huge impact on draw depth and the location of wall thickness variation. Every individual part design has to be evaluated for its depth of draw requirements. (Klein, 2009)

 Webbing: When the heated material makes contact with itself while forming and permanently bonds together causing a wrinkle, this phenomenon is called Webbing. Especially at outside corners on plug moulds, when the part requires a deep draw, this becomes a significant problem. (Klein, 2009) Therefore, it is important to review the part design for areas that will presumably create webbing.

 Undercut or Negative Draft: Undercuts or negative draft can cause problems in the thermoforming process while unloading the part, depended on their size and the used mould type. Special tooling technologies can be used in thermoforming to implement bigger undercuts into a part design. For small undercuts no special tooling techniques are required. For example, the polystyrene snap lid on a disposable coffee cup has an undercut to hold it onto the lip of the cup. These parts are typically formed with a cavity mould. Only the part shrinkage and an air blast are required in that case to remove the part. (Klein, 2009) However, it is suggested by Klein (2009) that the undercut section should not be greater than 0.76 mm below the mould surface to guarantee normal part removal. Deep undercuts in contrast, such as those shown in Figure 8, require more sophisticated tooling to remove the part. In this case the tool contains a simple hinged area that moves as the part is ejected (see Figure 8 above). Another solution are more sophisticated core pulls, driven by hydraulics, pneumatics or electrical solenoids as shown in Figure 9. (Klein, 2009)

Figure 8. Undercut and hinged release (Klein, 2009, p. 49)

Figure 9. Undercut and slide release (Klein, 2009, p. 49)

Part application issues The desired application is important to consider when designing a part. In the following section a few application issues that tie directly to the thermoforming process are explained.

12  Useful Temperature Range: After Klein (2009), thermoformed parts are formed rather than moulded. Resulting, the molecules within the part are under stress. This is why a thermoformed part may return to a flat sheet when it is placed in an oven and heated to its lower forming temperature. That phenomenon is called plastic memory. Therefore, it is important to understand the temperature range a thermoformed product is used in, during all possible applications. This temperature should be well below the minimum forming temperature. (Klein, 2009, p. 49)

 Strength Requirements: One of the fundamentals that any designer must consider, is the strength of the part. It is measured in the amount of impact a part can withstand. Measured indicators of strength are for example the tensile strength of a material or the stiffness of the part. The parts strength is primary determined by the geometry as well as the selected polymer. (Klein, 2009)

 Stiffness: According to Klein (2009), the stiffness of a part is measured by its resistance to bending. The amount of stiffness required depends on the final application of the part. For some applications, part stiffness is not to important. For others, like for example for a disposable drinking cup, a reasonable amount of stiffness is essential. The cup must be rigid enough to be held while fully loaded. This must be achieved, while maintaining the thinnest part possible to keep costs down. The stiffness can be increased by changing the part geometry rather than increasing the part thickness. Geometric options to increase stiffness are for example lips, corrugation, steps or domes. The use of these design options is common in the production of thermoformed disposables and packaging, where material saving is crucial. (Klein, 2009)

Quality requirements Designing a part, quality requirements like desired surface finish or optical qualities must be considered. The following section represents a few design issues influencing cosmetics and optics of the finished part.

 Cosmetics: First of all, it is important to ask if there are any specific cosmetic quality requirements. The thermoformed housing for a point of purchase terminal for example may have very high cosmetic requirements on the outer surface. Smooth, high gloss surfaces are often very difficult to create. hence chill marks, discoloration, and other process issues are quite visible. Furthermore, damage can occur to the surface during part removal, part trimming, and handling processes. Therefore, a flat finish with a texture should be considered whenever possible, as this tends to hide some of the named problems. (Klein, 2009)

 Optics: Optical quality parts are influenced by the same issues as discussed above. Additionally, the light transmission is of concern. Thermoforming, as a stretching process, leads to internal stress and varying wall thicknesses. Light transmission may be distorted by chill marks and stress lines, becoming visible after forming. (Klein, 2009)

13 Dimensional Tolerances: The numbers of variables in the thermoforming process make predictability of the dimensional tolerances difficult. Luckily inexpensive prototype moulds can be made quickly to test the design and determine actual tolerances to be held. The final part dimension is influenced by material shrinkage, process control and part geometry. Different materials shrink at different rates. Shrinking at different rates may also occur within one specific material, based on internal stresses produced during the sheet manufacturing process. The amount of heat applied during the process also determines the shrinking. If more heat is applied, the sheet will expand more and therefore shrink more after forming. The amount of shrinkage can be reduced by lowering the mould temperature or using cooling fixtures which hold the part after forming. (Klein, 2009) After Klein (2009), a general rule of thumb for the designer to estimate tolerances for thermoformed parts can be determined as follows: Packaging and disposables (made with thin gauge materials) should hold a process tolerance of plus or minus 0.25 mm, for up to a 152 mm part. 0.025 mm is added to this tolerance for every 25.4 mm above 152 mm. Therefore, a 584 mm long part would have a tolerance of plus or minus 0.43 mm. Non-packaging materials (thick gauge) should hold a tolerance of 0.76 mm, for up to 305 mm parts. 0.05 mm is added for every 25.4 mm above 305 mm. Therefore, the 584 mm long part mentioned above would have a tolerance of 1.32 mm. (Klein, 2009) For a better overview this rule of thumb, to estimate the tolerances for thermoformed parts, is illustrated in the table below.

Table 2. Estimate process tolerances for thermoformed parts (Klein, 2009, p. 51)

Process tolerance Added tolerance Part size for parts size for each 25.4 mm above part size Thin gauge ≤ 152 mm ± 0.25 mm + 0.025 mm Thick gauge ≤ 305 mm ± 0.76 mm + 0.05 mm

2.1.4 Tool Design The thermoforming mould not only defines the geometry of the part. It may also provide the parts texture, lettering, logos and other moulded in details. Furthermore, the mould acts as a heat exchanger. It has to be robust enough to produce the desired number of parts for which it was designed. Adequate air flow needs to be provided in the tool design, to evacuate the space between the heated sheet and the mould surface during the forming process. (Klein, 2009) For all those requirements, following influencing parameters are important:

. Mould material . Geometry/Shrinkage . Venting . Temperature control . Cavities

Those influencing parameters and parts of the mould design will be briefly presented in this chapter.

14 Mould material A thermoforming mould can be made out of a variety of materials. For low volume moulds, materials like wood, plaster, syntactic foam and thermoset materials like phenolic, epoxy and composite materials, including fiberglass reinforced polyester, are used. Low volume moulds, also called prototype moulds, are low in costs and quick to build. They are made to produce only a few parts or to test a part design. A negative aspect of all these named materials is their low thermal conductivity. They are all considered thermal insulators and therefore hinder the cooling process. For high volume thermoforming production moulds, Aluminium is the most used material. It conducts heat over 700 times better than epoxy. Production moulds are typically built with CNC machining technology. (Klein, 2009)

Geometry/Shrinkage The mould in thermoforming is typically produced larger than the part, to allow for part shrinkage. Like mentioned earlier in “Dimensional Tolerances” there are different variables that affect part shrinkage. These include for example, the polymer in use, the forming temperature, the mould temperature and the orientation of the molecules from the sheet production. This multiplicity of variables makes the shrinkage and geometry of the end product hardly predictable. Hence the best method to determine actual shrink rates is to test the process or use similar designed parts and moulds as examples. (Klein, 2009)

Venting All moulds in thermoforming need aids to evacuated the air in between the heated sheet and the mould. For pressure forming these are called vents and for vacuum forming these are vacuum holes. The primary purpose is to help the heated sheet to form and make contact with the mould surface as fast as possible. They may be shaped as holes, slots, channels or any other opening. The size must be small enough so that the heated sheet will not form into the opening, but large enough to quickly evacuate the air. Ideally these openings leave no mark on the part. Crystalline materials like polyethylene and polypropylene are quite soft and fluid-like at forming temperatures. This requires small openings in the range of 0.076 mm to 0.38 mm. Moulds used to form thick gauge ABS on the other hand may have openings up to 1.02 mm, without leaving a mark on the part. The location of the vent or vacuum holes is where the last points of the part are to be formed and where any air may be trapped between the sheet and the mould. (Klein, 2009) An example of the vent hole location on a plug mould is shown in Figure 10 on the left picture. In order to increase the air flow out of the mould, vent and vacuum holes are typically back drilled. (Klein, 2009) This is illustrated in the middle of Figure 10 and also magnified on the right side of this figure.

Figure 10. Mould with vent holes/vacuum holes (Klein, 2009, p. 56)

Temperature control Most aluminium moulds have some type of temperature control method to keep the correct temperature for the material being formed. Most commonly water is used, flowing through a controller that heats or cools the water to maintain a pre-set temperature. Water channels are machined into the mould, like shown in Figure 11, to remove the heat effectively. The path of the coolant should be designed in a way, to provide equal cooling within the whole mould. (Klein, 2009)

Figure 11. Mould cooling (Klein, 2009, p. 57)

Cavities Basic thermoforming moulds are often just machined into a block of aluminium. More sophisticated moulds have a standard mould base, where different cavity inserts can be added. For high volume parts multi-cavity moulds can be used, as shown in Figure 12 below. (Klein, 2009)

Figure 12. Thirty-two cavity mould (Klein, 2009, p. 58) The cavity inserts may also be made of a different material than the standard mould base in order to save costs. The base can be manufactured in a lower cost material as it does not require the same characteristics as the cavity. A mould may also have replaceable inserts in high wear areas. These areas can be replaced without the need to build an entire new mould. A trim blade for in-mould trimming is one example for such an insert. The blade can simply be replaced as it wears and gets dull. (Klein, 2009)

2.2 Laser in Dermatology The interest in the use of lasers in dermatology increased hugely over the past decade. Number and variety of lasers have increased dramatically. This has expanded the number of conditions treatable by lasers and also the number of clinicians who wants to include dermatological lasers in their portfolio of treatments. (Lanigan S. W., 2000) Asclepion is producing such lasers for dermatology. To get a deeper understanding of this special application area for lasers, the mechanisms of laser treatment of the skin is explained in the following, as well as safety aspects connected with a laser device.

16 “LASER” is an acronym that stands for Light Amplification by the Stimulated Emission of Radiation. (Goldberg, 2013) During stimulated emission an atom or molecule is stimulated by an absorbed photon. After this excitation it emits a photon of the same frequency as the exciting photon. When the released photon collides with another atom in the excited state another photon, identical in phase, frequency and direction, will be released as the atom returns to its stable state. For the principle of a laser it therefore is necessary that a large number of atoms in the excited state are present. (Lanigan S. W., 2000) Lanigan (2000) notes, that Laser light is considered coherent: all the light is of the same wavelength, also travelling in the same direction and in the same phase. These unique features of laser radiation are the reason for the explosive expansion of laser developments in medicine. (Lanigan S. W., 2000)

2.2.1 Components of a Laser All lasers consist of four primary components. One component is the laser medium, which is usually a solid, liquid, or gas. The next component is the optical cavity or resonator, which surrounds the laser medium and contains the amplification process. Another important component is the power supply or “pump”. The “pump” excites the atoms and creates population inversion. Last but not least, a delivery system is needed, to precisely deliver the light to the target. Usually this is implemented trough a fibre optic or articulating arm with mirrored joints. Goldberg (2013) mentions that lasers are usually named after the medium enclosed in their optical cavity. Gas lasers for example consist of the argon, copper vapour, helium-neon, krypton and carbon dioxide devices. An example for the most common liquid lasers is the pulsed dye laser. It contains a fluid with rhodamine dye. Representatives for solid lasers are ruby, neodymium: yttrium-aluminium-garnet (Nd:YAG), alexandrite, erbium and diode lasers. Based on their wavelength, nature of their pulse, and energy, all of these different devices are used to treat a wide variety of conditions and disorders. (Goldberg, 2013)

2.2.2 Mechanisms Laser Treatment of Skin When laser light interacts with tissue it can be reflected, scattered, transmitted or absorbed. Therapeutically the effect of absorption is used. The absorbing molecule within tissue, which in the skin could be for example haemoglobin, melanin, collagen or water, are called chromophore. The penetration of light into skin is ruled by the combination of absorption and scattering. Generally, the penetration into skin increases as the wavelength of light increases. In the far infrared however, where water absorption is important, the depth of penetration falls again. This phenomenon is used with the resurfacing lasers such as CO2 and Er:YAG. Haemoglobin has strong absorption bands at 418, 542 and 577 nm. Therefore, the depth of penetration of light at these wavelengths is weakened. Laser-tissue interactions can be grouped into: photothermal, photochemical plasma-induced ablation, photo ablation and photodisruption. The most important interaction in dermatology is photothermal. (Lanigan S. W., 2000)

The laser energy must be absorbed, in order to produce any effect within the skin. With absorption, radiant energy (light) is transformed to a different form of energy (usually heat) by the specific interaction with tissue. In case the light is reflected from the skin surface or transmitted completely through the skin without any absorption, there will be no biologic effect. If the light is imprecisely absorbed by any chromophore in the skin, then the effect will also be imprecise. Only if the light is highly absorbed by a specific component of skin, there will be a precise biologic effect. There are just three main components of skin that absorb laser light. These are melanin, haemoglobin, and intracellular or extracellular water. The absorption spectrum of each of these chromophores is well known. Manufacturing lasers, this information is used to develop devices

17 that produce light which is the right colour or wavelength to be precisely absorbed by each one of these components of skin. In this way collateral injury to the surrounding normal skin is minimized. (Goldberg, 2013)

2.2.3 Laser Safety Lasers are grouped into classes, to reflect the hazard potential of different lasers. This classification is based on the beam output, which is the power or energy emitted by the laser. The higher the class number the bigger is the potential hazard. (Lanigan S. W., 2000) Classification and standards for hand guided laser systems are set down as recommendations in the norm DIN EN ISO 60825.

Following the laser characteristics of each class are summarized:  “Class 1. Very low-power laser systems. Inherently safe. No hazard to vision.  Class 2. Low-power visible light lasers. Output power less than 1 m W. Blink reflex normally protects. Potential hazard if beam viewed directly for more than 1000 s.  Class 3A. Medium-power lasers. Wavelength varies from 200 nm to 1 mm. Output power less than 5 mW and irradiance less than 25 W/m². Safe for viewing with unaided eye. Blink reflex protects in visible range. Potential ocular hazard if used with focusing optics.  Class 3B. Medium-power lasers that are hazardous if viewed directly or by reflection. Output power less than 500 mW. Potential for skin injury as well.  Class 4. High-power lasers exceeding 500 mW. Direct beam, specular reflections and diffuse reflection all ocular hazards. Direct and specular reflections hazardous to skin. Some Class 4 lasers are capable of igniting flammable materials.” (Lanigan S. W., 2000, p. 7)

These dangers of laser radiation are the reason that safety is the most important aspect of properly operating a laser or other optical device. There is always some corresponding risk to the patient, the laser surgeon, and the operating room personnel whenever a laser is being used for treatment. (Goldberg, 2013) Therefore, an appropriate set of standards is needed to ensure that the equipment is being used in the safest fashion possible.

Goldberg (2013) names following measures for safety:  Training – Appropriate training and familiarization with the indications and uses of each device.  Signage – To prevent eye injury: appropriate signage on the laser operating room door (describing the nature of the laser being used, its wavelength and energy).  Eye Protection – For the laser surgeon and operating room personnel: special optically coated glasses and goggles that match the emission spectrum of the laser being used. For the patient: e.g. metal scleral eye shields (placed directly on the corneal surface) or burnished stainless steel eye cups (fit over the eyelids and protect the entire periorbital area)  Measures against Laser Plume – Lasers that ablate tissue and create a plume of smoke can potentially harm the laser surgeon, patient and operating room personnel. Methods to prevent potential inhalation injuries are: laser-specific surgical masks and a plume/smoke evacuator.  Measures against Laser Splatter – Treating tattoos or benign pigmented lesions, the impact of the pulses can disrupt the surface of the skin, sending an explosion of blood and skin fragments. Solutions can be to supply the device with a nozzle or tip that can collect these particles, or to apply a sheet of hydrogel surgical dressing on the surface of the treatment site and discharge the laser through this material to the target.  Measures against Fire – Any flammable material, including acetone cleansers, alcohol-based prep solutions or gas anaesthetics are recommended to be restricted from the laser operating room.

18 2.3 EMC (Electromagnetic compatibility) When an electrical device is designed and produced it has to meet all standards of the EMC (Electromagnetic compatibility) directive. According to Williams (2007), the definition of EMC (as it appears in the International Electrotechnical Vocabulary) is: The ability of a device, equipment or system to function satisfactorily in its electromagnetic environment without introducing intolerable electromagnetic disturbance to anything in that environment. Gonschorek & Vick (2009) mention several measures which must be taken in order to achieve the EMC of a device or system. First of all, the layout of the circuit and the design of the printed circuit board needs to be planned carefully. This includes the support of the inner arrangement of components and the wiring of equipment. Guidelines are formulated for the construction of the system, to meet the standards of EMC. Measures include the application of grounding, filtering and shielding guidelines as well as the implementation of problem-matched wiring and cabling. The following possibilities are available to eliminate some common interference:  Supress currents (only if the currents are not needed as signal currents)  Damp currents (in such way, that the effects on other systems are negligible)  Drive additional currents, in order to produce fields which, compensate the initial fields.

Since many factors must be considered when looking at the EMC aspects of a design, and it is easy to overlook an important point, Williams, T. introduces a Design checklist in his book “EMC for Product Designers”.

For the shielding of a device there are following guidelines listed:  All metallic structures shall be designed as if they were electrical components (consider their stray capacitance and inductance).  Consider separate enclosures: enclose particularly sensitive or noisy areas with extra internal shielding  Avoid large or resonant apertures in a shield, or take measures to alleviate them  Avoid dipole-like structures in a metallic enclosure  Ensure that separate panels are well bonded along their seams (e.g. by using conductive gaskets)  Design plastic enclosures to allow internal conductive coating  Use multiple internal tie-points to minimize box resonances

It is also advised by Williams to test and evaluate for EMC continuously as the design progresses. Various materials are offered by many manufacturers to improve the conductivity of joints in conductive panels. (Williams, 2007)

 Gaskets and finger strip: The effectiveness of shielding can be improved by reducing the spacing of fasteners between different panels. The conductive path between two panels or flanges can be improved by using for example conductive gasket, knitted wire mesh or finger strips. (Williams, 2007) The usage of such conductive elastomer gaskets is shown in Figure 13.

Figure 13. Usage of conductive elastomer gaskets (Williams, 2007, p. 393) These components are inserted in between the mating surfaces and compensate the irregularities of each surface. Thus they ensure continuous contact across the joint, so that shield current is not diverted. (Williams, 2007) The application of finger stripes is shown in Figure 14 below.

Figure 14. Usage of beryllium copper finger strip (Williams, 2007, p. 393)

 Conductive coatings: For aesthetic or cost reasons, many electronic products are enclosed in plastic cases. By covering one or both sides with a conductive coating, these can be made to provide a degree of electromagnetic shielding. (Williams, 2007)

20 3 CONCEPT DEVELOPMENT

In this chapter the working process is described. Introductorily, the requirement specifications are listed and the pre-studies and the ideation process is described. Furthermore, the conceptual phase, with concept generation, modularisation and evaluation and screening is outlined, leading into the final concept.

3.1 Requirement Specifications In the requirement specifications, all the criteria are listed that the developed product has to meet at the end. Beside these demands, the requirement specifications are extended by a wish list, including optional but not essential qualitied of the product to be developed. The performed pre-studies and the requirements, expressed by Asclepion, lead to following requirements specifications:

The following requirements were given by the company: • Thermoformed • Modular system • Easy Assembly/Disassembly • Display: size 10,1 inch, aspect ratio 16:9 (one which stays up to date as long as possible) • Easy to clean (hygienic) • Easy to manoeuvre (e.g. sufficient number of handles) • 4 movable wheels (use of same parts) • Good ergonomics (e.g. height of the handles, screen placement) • Durable (e.g. material surface, static properties of housing) • EMC (electromagnetic compatibility) • Laser safety • Fit to corporate design

Among the wish list were the following features: • Movable display • Extra placement area • Solution to fix line cord • Low maintenance

3.2 Pre-Studies The pre-studies for the presented product development process include three main work packages. The first work package consisted of research and information search within the company. For this, the assembly and production of present devices was observed. Supportively, knowledge about the third party housing production was compiled. Another work package is a short market analysis of competitor products. An excerpt of the findings will be shown in the subchapter 3.2.1 Market Analysis below. The third work package is a customer survey and observational study which is done in the context of customer trainings offered by Asclepion. The results and analysis of the survey will be shown in 3.2.2 Customer Survey.

21 3.2.1 Market Analysis A short market research was done to identify competitors on the market. The focus was on devices of the same class like the machine to be developed for Asclepion. In the following pages a selection of competitor products in the category” laser systems for medical aesthetic market” is shown.

“PicoSure Laser” (by Cynosure) “PicoWay Laser” (by Syneron Candela)

Tattoo Removal, Wrinkle, Acne, Pigmented Lesions Tattoo Removal, Pigmented Lesions, Skin Rejuvenation

(TATAWAY, 2016) (Verwijderen, 2014)

Figure 15. Competitor products (Cynosure, Syneron Candela)

“Q-Switched Nd-Yag Laser” (by IDS Lasers) “RevLite” (by HOYA ConBio)

Tattoo Removal, Acne, Pigmented Lesions Tattoo Removal, Skin Rejuvenation

(System., n.d.) (Inc, 2015)

Figure 16. Competitor products (IDS Lasers, HOYA ConBio)

“HERA XP” (by UNION MEDICAL) “Spectra” (by Lutronic) Tattoo Removal, Pigmented Lesions, Skin Tattoo Removal, Pigmented Lesions, Skin Rejuvenation Rejuvenation

(MedicalEXPO_Products, 2016) (MedWOW, 2014)

Figure 17. Competitor products (UNION MEDICAL, Lutronic)

“VENUS IV Plus” (by UNION MEDICAL) “Q Plus A” (by Quanta System) Tattoo Removal, Pigmented Lesions, Skin Tattoo Removal, Pigmented Lesions, Skin Rejuvenation Rejuvenation

(D&PS, 2013) (MedicalEXPO_Alexandrite, 2016)

Figure 18. Competitor products (UNION MEDICAL, Quanta System)

“SINON” (by Alma Lasers) “Soprano ICE” (by Alma Lasers) Tattoo Removal, Pigmented Lesions Hair Removal

(Lasers O. , 2016) (Lasers A. , 2015)

Figure 19. Competitor products (Alma Lasers)

24 It becomes obvious that most laser devices on the market have a polymer front plate which is applied to a metal case, even as the stand alone devices of the product family of Asclepion to be redesigned. Other housings (e.g. the “PicoWay Laser”) seem to be made of one piece. This makes them appear more unified. All machines but one has some kind of handle at the front, to be able to pull the machine towards the operator or around. Only three devices seem to have a movable display. All of those laser devices have four movable wheels to be able to manoeuvre the machine. Most of the housings have quite complicated shapes, which are not easy to clean. The market research helps to get an impression of what other manufacturers consider as important and what is out there on the market.

3.2.2 Customer Survey In order to get another point of view on the importance of different design aspect for a laser device, a customer survey was carried out. During training sessions, 17 users (customers, mostly doctors) were asked about their experiences using the machines from Asclepion. Questions were asked regarding the convenience of Asclepion devices to figure out which characteristics are important for the end user, but also to be able to improve the overall satisfaction of the new design. The whole questionnaire handed out is shown in the Appendix under “Questionnaire Operator Convenience”. In this subchapter, the results and analysis of the survey will be illustrated.

One question is about the importance of a movable display. The users have been asked: “Our devices have a fixed display. Are you willing to pay more money for a movable display?” The results are shown in Figure 20 below.

Are you willing to pay more money for movable display?

1 Yes 2 6 No

Not sure

8 Abstention

Figure 20. Survey results: movable display For almost half of the respondents a movable display is not too important. However, for 6 of the respondents a movable display would be such a beneficial feature that they are willing to pay more money for it. Furthermore, the ergonomic properties are interesting. To gather information, the following question was asked: “Are the ergonomic properties of the device satisfying? (Device shape, number of handles, height of handle, storage area, …)” If any respondent answered this question with no, they were asked to concretize the weak points on blank lines underneath the question. The tendency of satisfaction with the ergonomic properties of Asclepion devices is shown in Figure 21 below.

25 Are the ergonomic properties of the device satisfying?

3 Yes

No 2

10 Abstention

Figure 21. Survey results: ergonomic properties Most users are satisfied by the ergonomic properties. Some weak points are named by the respondents unsatisfied with the ergonomics. One disruptive factor is the inflexibility of the hand piece hose of the “MeDioStar NeXT”. Furthermore, the few number of handles is criticized as well as the wires hanging down, being overrun by the device. Another question was about the operator position, to adapt the display angle for the user adequately: “In which position do you preferably operate the device?” The answers to this question are visualized in Figure 22.

In which position do you preferably operate the device?

1 sitting 5

5 upright

both

Abstention 6

Figure 22. Survey results: operating position The results show a fair balance of operating positions. One option to meet the resulting broad viewing angle area is the use of a movable display. For a fixed display on the other hand the survey results show the importance of a well-chosen display angle and a great viewing angle stability of the display, to be able to operate the device both upright and in a sitting position.

26 3.2.3 Observational Study A questionnaire survey, like presented in the previous chapter is after Kang & Suto (2013) one of the most commonly used research methods by researchers when they try to explore a user’s opinions and needs. Even so, it is difficult to find out the user’s potential needs with the questionnaire survey. Observational studies in a design process are a useful method to know the user’s various types of needs including potential needs. (Kang & Suto, 2013) Observation as a research method is used during the presented design process in form of an observational study.

During the study the treatment of patients was observed, in order to get a deeper impression of the operation procedures, utilisation properties and the convenience in handling of a laser device. The field study was performed in the context of two different training sessions offered by Asclepion for clients and potential customers. Scheduled was the treatment of pigmented lesions, vascular treatments and hair removal. It was observed how the preparation for the treatment is done, as well as the handling of the machine during treatments and also how the cleaning is performed.

The observations are described in the following section. During preparation and treatment, the storage surface on top of the devices is used for accessories. The operation of the display and the setting of the required parameters is mostly performed by the user whilst sitting. Still, the operator has to be able to read the display during treatment from different angles and while standing. Some difficulties were noticed during treatment. The hose of the hand piece of the device “MeDioStar NeXT” appears to be heavy and a bit inflexible, which makes it hard to handle for some users. Furthermore, the importance of an adequate sized handle becomes obvious to maneuverer the device during treatment. A disturbing factor is also the wire of the foot switch, since it was sometimes overrun by the device wheels. The shape of the hand piece does allow easy cleaning after treatment. In contrast, the shape of the surface on the machine can be improved in respect of cleaning. Since the room is heating up quickly caused by the running laser device, the importance of a proper ventilation in the machine as well as in the room becomes clear during field studies.

Through observation a deeper knowledge and familiarity with the laser security guidelines was achieved and the users are observed dealing with those regulations. The observation helped to understand the needs of the user as well as it enables to identify some potential needs which can be served by the redesign of the housing.

3.2.4 Development of Brand DNA In order to design a new housing for Asclepion, it is important to know what distinguishes a product of Asclepion from competitors and that the new design fits the corporate identity of the company.

Regarding to Luthra (2016), corporate identity is defined as a combination of colour schemes, designs, words, etc., that a firm employ to make a visual statement about itself and to communicate its business philosophy. It is also mentioned that corporate identity is an enduring symbol of how a firm view itself, how it wishes to be viewed by others, and how others recognize and remember it.

At first, to truly understand Asclepion’s corporate identity, the brand’s DNA had to be defined. To accomplish that, a technique called “Microscoping” exercise is used, like suggested by Ingle in the book “Design Thinking for Entrepreneurs and Small Businesses”. Ingle explains to the reader that the brand is the business’s personality, the embodiment of what the company stands for and is known for. The brand is what distinguishes the company from their competitors. Accurately defining the brand can be accomplished in an afternoon with the senior

27 leadership team or other important stakeholders using a design thinking activity called Microscoping. This activity helps to uncover the brand’s DNA by exploring both the rational and emotional sides of the brand. During Microscoping exercise, the brand is defined as it needs to be, there is no need to define it in its current state. (Ingle, 2013)

For the present project, the Microscoping exercise is applied on the brand “Asclepion” with the help of two members from the marketing department of this company. The exercise starts with filling the upper segments (rational aspects) of a chart, then the bottom half of the chart (emotional aspects) has to be filled. The completed chart of the Microscoping exercise for the brand DNA of Asclepion is shown in Figure 23 below.

Figure 23. Microscoping brand DNA chart for Asclepion Finally, the task is to define the brand’s core, using keywords from the content in the graph. The challenge is to narrow that list to no more than five, so the team ultimately asks themselves the hard question: “What is absolutely mandatory for our brand’s success?” The answers form the brand’s DNA. (Ingle, 2013, p. 82) The brand DNA of Asclepion is described by following four attributes: Service, Innovative, Professional and Secure.

With the brands DNA in mind the next step in the ideation process is to generate a variety of ideas. This is accomplished with the help of “Morphological analysis”. The tool and its outcome will be discussed in the next chapter.

3.3 Ideation After Gonçalves et al. (2014), searching for, retrieving and using particular stimuli for inspirational purposes is often achieved via the implementation of different idea generation methods. Methods can be informal activities, such as active/passive searching, collaborating, and socialising or very formal procedures like brainstorming and morphological analysis. In this subchapter some of the used ideation methods are described. Mainly brainstorming and morphological idea generation were used during the ideation phase.

28 3.3.1 Brainstorming Gonçalves et al. mention that brainstorming is probably the most popular idea generation method and often reported as one of the commonly used approaches during idea generation by practicing designers, and often recommended as an idea generation method in different organisations.

With the knowledge from pre-studies and especially from research and information search within the company, brainstorming was done regarding all requirements for the new product. A mind map was created, which is shown in Figure 24 below, to get an idea of all different areas to think about during the design process.

Figure 24. Mind map: requirements and ideas for new modular housing

29 All those collected elements from the mind map need to be considered for the final concept. Though first of all an idea, especially for the geometry of the housing, has to be created.

3.3.2 Morphological Idea Generation To achieve this first step, the morphological idea generation is used. The use of this ideation tool is explained within the next pages.

Shetty explains in “Product Design for Engineers” (2015) the morphological analysis as an organized method to enable designers to compare the various attributes of a problem and create new forms of design. A morphological chart is used to stimulate designers to identify novel combinations of elements and recombine them to deduce a solution. It helps to generate a range of alternative design solutions for a product and to widen the search for potential new solutions. The steps to perform the morphological chart method are stated by Shetty as follows:  Step 1. List the essential features of the product.  Step 2. List the means by which each feature can be achieved.  Step 3. Prepare a chart that contains sub solutions.  Step 4. Identify the possible combinations of sub solutions to make the product.

This morphological analysis is applied in the present work as described by Shetty. Five essential features are picked: shape, modules, display, handles and laser warning lamp.

Means to achieve modularity are for example to stack the same modules onto each other, building a tower which includes the whole device or to apply modules only onto the front and the top of a metal case. Different solutions for the feature “Display” are e.g. touch-/non-touch display or movable-/non-movable display. All considered design elements with examples for corresponding solutions are shown in Table 3 below.

Table 3. Morphological idea generation, features and corresponding solutions Features Solutions Shape - display sticking out - circumferential shape of top edge - fore front shorter than back - triangular shaped front with - all vertical edges rounded extruded cut out Modules - stack modules to a tower - apply modules onto front and top of metal case Display - touch/non-touch

- movable/non-movable Handles - integrated into the shape - on the side - on front - different cross sections - on top of the display Laser - gill similar, on front warning - Asclepion dots, on front lamp - band, on top of display

The result of this morphological analysis, the morphological chart, is shown in Figure 25 below. As features on the left side, the design elements are listed. On the right side, different variations of solutions for those design elements are specified.

Figure 25. Morphological chart for modular housing design The shown morphological chart comprises only a selection of all variations of ideas. The method helps to explore possible combinations of design elements and to evaluate them by suitability. In this way the morphological method influences the further design and specifies a direction.

3.3.3 Combination and Evaluation of Ideas The goal is to present 5 models that contain different morphological elements to discuss them with the company. Not all elements were combinable with each other. For example, the overall shape sometimes induces a certain module structure. All 5 sketches are ideas to visualize how the housing could look as a whole, even though features can be adjusted. The following 5 solutions, shown in Figure 26, are presented to the company.

Figure 26. Selected principal solutions In a meeting with some members of the marketing department of Asclepion the five selected principal solutions were evaluated with special regard to the expectations, wishes and ideas as well as the fit to the image of the company. During selection process it became obvious, that two of the presented ideas are a lot to close to a competitor product design-wise. Namely the first and fifth idea sketch in Figure 26 resemble the

31 product “PicoSure Laser” by Cynosure (see Figure 15, left). By this fact they were eliminated from the selection process. At the end of the process the two ideas shown in Figure 27 (referred to as Idea 1 and Idea 2) are chosen to be developed further into detailed concepts. With this assortment of ideas, the process is passed onto the conceptual phase.

Idea 1 Idea 2

Figure 27. Two favourite ideas

32 3.4 Conceptual Phase In the concept generation phase the two favourite ideas are visualized as concepts in form of CAD- models. 3.4.1 Concept Generation First of all, Concept 1 is developed from Idea 1. It is shown in some variations in Figure 28 below. This concept is inspired by other members of the product family. The handles and the shape of the device “QuadroStarPRO” (see Figure 2, right) are a recognition factor. Therefore, the triangular shaped handle of the “QuadroStarPRO” is embedded into the side of the housing in two versions of Concept 1, like illustrated in Figure 28 (both right devices). Also the vertical front line, which can be found as a design element in all previous stand-alone devices of the product family (Figure 2, three left pictures), inspired the shape of Concept 1.

Figure 28. Concept 1, rough, in variations From the rough CAD-models shown in Figure 28, a more detailed CAD-model is developed in this ideation phase. Like illustrated in Figure 29 some features like buttons, a logo and the ventilation area are added and the shape of the housing is refined.

Figure 29. Concept 1, detailed

33 Differentiation of the devices within the product family is provided by colourization of the polymer mat on the top of the device. Also the side walls of the cut-out in the front are coloured (illustrated in Figure 30, left).

Figure 30. Concept 1, left: laser warning lamp and handle; right: ventilation Furthermore, a handle is integrated in form of a grip plate into the cut-out underneath the display. Additionally, laser warning lamps can be placed behind the handle, illuminating the whole surface of the cut-out. Both features are shown in Figure 30 on the left picture. The idea for the ventilation area is inspired by the Asclepion logo (see Figure 30, right picture).

The second concept, developed from Idea 2 is shown in a CAD-model in Figure 31 below. For this concept the geometrical shape is generated with the display as a main anchor point defining the lines of the housing. The housing is bended in towards the angled display and closes with a coloured band above the display, which underlines the special geometry. Furthermore, the coloured band acts as a differentiation feature for the devices of the product family and can be coloured differently depending on each device. Another main element of Concept 2 is the laser warning lamp in form of LEDs which are embedded into the housings front curvature. This functions as a security feature, indicating an activated laser. At the same time, it serves as a second differentiation feature, illuminating in the device colour. The laser warning lamp can also be integrated into the coloured band instead.

Figure 31. Concept 2

34 3.4.2 Modularisation Besides the geometrical shape of the housing, a concept for modularisation has to be developed since a modular housing for the whole product family is sought. To save material and to keep the number of thermoformed parts low, it is decided to use a metal case and mount the housing only onto the front and the top of the metal case.

The devices vary mainly in depth caused by the different length of the optical bench, which is related behind the display and takes up the whole length till the back panel. The dimensions of the front (height, width) differ only slightly between devices. Therefore, two front modules are created which can be used for the whole product family. The top module will differ in length from one device to the other. This idea of modularisation is applied to the CAD-model of Concept 1 and Concept 2. The modularisation for Concept 1 is illustrated in Figure 32 below.

Figure 32. Concept 1, modularisation A drawing with the main dimensions for this CAD-model can be viewed in the Appendix under “Drawing Concept 1” on Page 62.

The top module of Concept 2 encloses the whole length of the housing like it is shown in Figure 33. This is motivated by the objective to design a machine which can be used equally with or without the polymer mat. Also the display has to be integrated into the top module, since integration into the front module would provoke an undercut in production. As outlined in the section “Undercut or Negative Draft” on page 12, undercuts require more sophisticated tooling to remove the part and this creates added costs. For thermoforming it is therefore strived to avoid undercuts.

Figure 33. Concept 2, modularisation Both modularisation concepts consist of three parts, two front-modules and one top-module mounted onto a metal case. The realisation of the modularisation on the final product (with exact dimensions) is shown in chapter 5.2 Modularity.

3.4.3 Evaluation & Screening A concept presentation was given to representatives of the marketing department, engineering department and to the project leader of this project. In this meeting the modularized concepts were presented and discussed in detail. One meeting later the decision is taken to use Concept 2 since some qualities militate for this concept. Concept 2 is easy to clean due to its even surface and plain shape. Furthermore, the design fits to the brand DNA and its attributes professional and innovative. In addition, some recognition is granted for the customer with Concept 2, as the handles resemble those of older devices.

The next step is to finalize this concept in all details and in this way lay the foundation for the production oriented CAD-modelling of the final product. The final concept development is amplified in the next chapter.

36 4 FINAL CONCEPT

For the chosen concept final decisions has to be taken for the geometry, the implementation of the ventilation area as well as safety features and ergonomics. This chapter illustrates possible solutions for those features and the associated selection process, leading into the final concept.

4.1 Geometry First decision to be taken was about the Shape of the housing around the display. The first developed concept has warpage in the shape of the coloured band on top, which is shown on the left picture in Figure 34, defining the edges of the housing around the display. With this outer contour screen visibility from a side angle may be restricted. Therefore, another version of this concept is generated in which the warpage towards the display is taken away. This is illustrated in Figure 34, on the right picture.

Figure 34. Shape of coloured band, different versions For this new version of the concept, various features of Solid Edge are used to shape the radius on the emerging edge differently. At the end, the decision is taken for a version modelled with the “Round” command. With this, the geometry for the final product is settled.

4.2 Product Identification Like described in 3.4.1 Concept Generation, features are introduced to differentiate the devices within the product family. For this concept those are mainly the coloured band and the laser warning lamp. Furthermore, a label with the device name is applied underneath the display for differentiation. Two different options for the implementation of the label are presented in Figure 35.

Figure 35. Label “MCL31 Dermablate”, different versions The label on the left version is made of separate letters, meanwhile the label in the right version is made from a whole piece of clear polymer, with the device name printed on the surface facing the device. The second version (Figure 35, right picture) is chosen for the final product since it is easier to clean and hence more hygienic.

37 4.3 Laser Safety Like mentioned earlier, the laser warning lamp acts as a safety feature but also as a differentiation feature. As a matter for safety the LEDs of the lamp emit light when the laser is activated. Three versions to realize the laser warning lamp are excogitated, shown in Figure 36.

Figure 36. Laser warning lamp, different versions In the first version on the left picture, the feature is carried out as three different sized half cones, integrated into the housing surface. They are realized during production through the shape of the thermoforming tool. The middle picture of Figure 38 illustrates how the corresponding module looks like from the inside. The LEDs are inserted through small holes on top of the half cones so the light is reflected in the curved surface of each half cone, like illustrated in Figure 37.

Figure 37. Implementation laser warning lamp feature The laser warning lamp shall illuminate in the device colour. This is realized either through adjusting the LEDs accordingly, or by sending the light through a transparent and coloured polymer like PMMA. That principle is to be applied for the second version of the concepts (middle picture in Figure 36). The shape, three circles, is inspired by the logo of Asclepion (for logo see Figure 1). For realization, three PMMA discs are inserted into designated opening in the housing. LEDs are mounted behind and shine through the transparent and coloured polymer. The last option shown in Figure 36 is a laser warning lamp integrated into the coloured band above the display. Here the same principle as for the previous concept applies. The LEDs are mounted behind the transparent polymer on height of the display and shine through the coloured band in that area. The last concept would probably provide the best visibility of the laser warning lamp compared to the other concepts, where the lamps are situated on height of, or underneath the handle. Choice is made for the first version in Figure 36. This concept is assumed to be easiest integrated in the production and assembly process of the device.

38 4.4 Modules The first draft how the thermoformed modules look like, is illustrated in the rendered pictures of all three modules in Figure 38. From left: top-module, front-upper-module, front-lower-module. Also the CAD files were pre-reviewed together with a thermoform expert from BWF for produce- ability. The CAD model was inspected for undercuts and drawing depth and especially for too small radii.

Figure 38. Modules, thermoform able, first draft An undercut appears on the top module in the display area (Figure 38, left picture), since in this concept the display is applied from the outside into the provided frame. Changing the location of the display to the inside instead, simplifies the assembling and avoids undercuts in the thermoforming process. The assembly and disassembly of the device will be explained in more detail in chapter 5.5 Assembly/ Disassembly. Developing the final concept to the final product, some radii hade to be increased as well, to guarantee a successful thermoforming process. Those changes and how the thermoforming guidelines have been applied to the final CAD model will be amplified in chapter 5.2 Modularity.

39 4.5 Ventilation In Figure 39 below, two ideas for the realization of the ventilation area are shown. The idea behind those variants is to integrate the Asclepion logo into the side panel. In this way the ventilation area reflects the company additionally to printed logos on the housing.

Figure 39. Ideas ventilation area On the left picture in Figure 39 the first idea of a ventilation area design is shown. In this concept the ventilation area is concentrated on the lower area of the metal case. It consists of big ventilation holes in the middle whereas the hole size is decreasing towards the edge region. Therewith it is based on the Asclepion logo with its grid element of growing dots (see Figure 1), which is additionally included as ventilation openings in that design.

The second concept of how to design the ventilation area is based on the idea to use inverse graphics. Instead of cutting out the shape of the logo, the background is a grid of holes and the logo is left as the only surface without holes, like it is shown in Figure 39 on the right picture. The whole area of the side panel is used for ventilation.

Compared to the first concept, where the ventilation area is limited to the bottom area, the second concept provides a broader area of ventilation. Also, in the first concept the holes in the middle are likely to get too big, which would cause problems safety wise, since the device has to pass an electrical safety test to provide protection against accidental contact. In the first evaluation the second concept was chosen to be further developed.

One downside of the second concept was the missing company name in the ventilation area. It was added as a cut out in the CAD model of the final concept, as shown in Figure 40 below.

Figure 40. Ventilation area, improved

4.6 Improvements on handles and display In the final stage of the conceptual process, a CAD model combining all these previous specified decisions was carried out. The result is shown in Figure 41 below. This final concept is presented in a meeting to the project leader, selected representatives of the departments and the deputy general manager.

Figure 41. Final concept, CAD-model

41 After the presentation and during that meeting parts of the design were discussed. For example the practicability of the design for assembly and disassembly as well as the implementation of the display and the name label. For some parts final changes and improvements were defined with the attendees. Those improvements will be presented in the following.

Handle width First of all, the width of the handle has been increased. The inside surface of the old handle (left picture, Figure 42) touched the housing on both side surfaces, which makes it impossible to clean and disinfect this area properly. For this reason some width has been added for the new handle to make the whole area underneath the handle accessible for cleaning, like it is shown in Figure 42 on the right.

Old New

Figure 42. Handle, improvement Display area Also, the display area is discussed. One idea and request is to realize the whole surface on which the display is applied as a glass surface. This is shown in the figure below. Hence this would complicate the production and make assembly and disassembly more difficult this idea is refused at the end.

Figure 43. Display, discussed version Another critical point is identified in the quite small frame of the display. The distance between the top edge of the display and the top edge of the device represents only 7 mm, like illustrated in Figure 44 on the left.

Figure 44. Display, increased distance This distance has to be increased to 12.5 mm, to add some tolerance and space for the display rear body itself. This is shown in Figure 44 on the right.

43 5 FINAL PRODUCT

The implementation of the final product is described in this chapter and the application of the knowledge presented in the frame of reference chapter will be explained in this context.

5.1 Product Family With all the final corrections from last chapter, the final concept is applied to the three devices of the product family like explained in 1.2 Purpose. The new appearance of the product family will be presented in the following.

In Figure 45 below, the developed design, applied to the product family is shown. The device “MeDioStar NeXT PRO” itself is a table top device. Only half of the height compared to the other devices is filled with equipment. For manoeuvrability, a buggy with wheels is supplied with the device upon purchase. On the very left of Figure 45 the “MeDioStar NeXT PRO” is shown as a stand-alone version. Right beneath on the ground, the table top version without the buggy is placed. The dimensions of the modular design are planned for the lower module to fit the front of that buggy.

Figure 45. Product family, final design (from left to right: “MeDioStar NeXT PRO”, “TattooStarPICO” and “MCL31 Dermablate”) For this project, the corresponding RAL colours of the devices in the print products at Asclepion are chosen for differentiation purpose. Those colours are applied to the particular differentiation features, coloured band and laser warning lamp, like it is illustrated in Figure 46 and Figure 47.

Figure 46. Product family, bird's eye view The simplicity of the front of the modular housing design becomes obvious examining the front view in Figure 47, which is mainly related to the attempt of developing a thermoform able shape for the housing. Thereby room is left on the front for eventual prints or design features involving the Asclepion logo.

Figure 47. Product family, front view

45 The first device of the product family, which will be reissued with the new design, is the “TattooStar” (see Figure 2). With the new name “TattooStarPICO” this machine will reach marketability first. Therefore, in the rest of this chapter the final product will be explained exemplary with this device.

5.2 Modularity Modularity has been developed by searching for the best common denominator in dimensions of the three devices. The approach is pictured in Figure 48 below.

Figure 48. Modularity, find common denominator in dimensions For length and especially height of the three devices it is aimed to find a mean value which fits for all of them without restricting design engineering afterwards. Therefore, the dimensions of the metal housing from the present devices are used to have an indicator for the requested dimensions.

The metal housing has to provide the same space as before. In the new design there are round edges intended on the back side of the device, which increases the length of the metal case. With the new polymer part of the housing in turn, length is saved because it does not add as much length to the device as the old one. For the new device “TattooStarPICO”, a length of 1000 mm is estimated by the development department, which exceeds the required length of the other devices by far. The need for an extra top module for the “TattooStarPICO” results.

Also in height a mean value among the dimensions were found. After consultation with the development department, it turned out to be technically feasible to reduce the height of the “TattooStarPICO” by 50 mm. “MCL31 Dermablate” and “MeDioStar NeXT” on the other hand would gain about 50 mm of height with the modularisation. For those two devices it is beneficial to gain 50 mm in height, since thereby the display is brought closer towards the user and also the mirror joint arm and the hand piece get closer to the treatment procedure.

46 5.3 Design The application of knowledge from the frame of references for the implementation of the shape as well as the adaption of the design to special requirements for a laser device is described in the following subchapter. 5.3.1 Geometry The engineering detail drawings with all dimensions for the designed housing of “TattooStarPICO” are shown in the APPENDIX under “Engineering drawings”.

During the design of the polymer housing and especially CAD modelling the shape, the thermoforming guidelines, from chapter 2.1.3 Part Design are followed. Some geometries had to be changed considering the guidelines and preparing the CAD-model for thermoforming. The process of this preparation is explained in the following.

Wall thickness variation The determining aspect for the decision whether to use a plug or a cavity mould in case of the Asclepion housing is the surface quality. To achieve a controllable surface, the outside of the product should be touching the mould. Therefore, a cavity mould has to be used. As a result, the top part of the housing will be the thinnest, since this part of the heated sheet touches the mould at last during the thermoforming process. In addition, the top part is the one with the most details in the housing. With an initial sheet thickness of 6 - 7 mm, the top part of the thermoformed housing would have a remaining material thickness of ≤ 1 mm, if the radius in that area is retained with R=1 mm, like planed in the beginning. Such a small wall thickness makes the top region sensitive to impact. (Bitai, 2016) Increasing the radii in the top area would produce some relief for this problem and in this way decrease wall thickness variation.

Material and Draw Ratios

To decide whether the stretch ability of the selected material is adequate for the application the linear draw ratio is calculated like shown in equation (2) with measurements from the performed CAD model. Only the top module is analysed as an example in the present thesis. The part is assessed in the direction requiring maximum draw. The section view in Figure 49 below shows the used direction of draw. It is a section view on a parallel plane to the front panel of the top module. Before forming, the line length is 364 mm and after forming 722 mm. This gives an LDR of 1.98, as it follows from equation (2). The line is now 198% of its original length. Application of this draw ratio onto material selection is mentioned in chapter 5.6 Materials.

Figure 49. Section view, top module

47 Part Geometry and Design Guidelines

The part geometry should meet the thermoforming design guideline. The application of most aspects is explained briefly, in the same order as the aspects in the guideline were shown earlier.

 Corners and Radii: The thermoforming guideline calls for the largest radius possible. For this reason, the radius of the top module underneath the elastomer mat was increased during the modelling process. Now the radius of 15 mm is suitable for the production. (Bitai, 2016) Especially for the smallest radius on the very top of the module, the need of increase becomes obvious thinking about the resulting thin wall thickness explained earlier. Therefore, the radius has been increased to 1.5 mm like it is shown in Figure 49 (see also “Engineering drawings” in the APPENDIX). Further increase of that radius may be necessary.

 Draft Angles: Like mentioned in chapter 2.1.3 Part Design, cavity moulds do not necessarily require any draft although up to 2 degrees is suggested. The front modules and the top module are produced in a cavity mould. Hence no draft is required. The front module design does not deliver any draft. On the other hand, the top module has a drafted wall on the front, which makes ejection from the mould easier.

 Webbing: Webbing is a significant problem at outside corners on plug moulds when the part requires a deep draw. Therefore, it is important to review the part design for areas that are presumably to create webbing. In case of the designed housing for the “TattooStarPICO” this problem will not arise, since it will be produced with a cavity mould. The cavity mould contains also only one plug area at the top module, with very small draw. This is the area where the coloured ring will be inserted later on.

 Undercut or Negative Draft: The design of the screen area was likely to produce undercuts in the first drafts. This problem was solved by assembling the screen first, before assembling the polymer housing. The final housing design for Asclepion therefore contains no undercuts which could cause problems in production.

Part application issues

 Strength Requirements The strength is measured in the amount of impact a part can withstand. Mechanical properties which can be important for a product, depending on application, are e.g. limiting bending stress, yield stress, tear resistance or impact strength. Impact strength is the most important quality among those for a product like a housing. Supposable impact while using a laser device are for example that the device probably hits a wall or furniture while be moved around. In addition, a hand piece or bottle could hit the housing while usage of the machine. Another scenario could be that during assembly or disassembly the housing falls onto the floor, from a height of 1 m. Therefore, the impact strength resistance of the top part of the housing has to be examined deeper, since the wall thickness and with this the impact strength is potentially too small. During material selection the impact strength plays an important role.

48  Stiffness All stiffness of the housing is provided by the material. No special part geometry is implemented, since it would destroy the appearance of the housing.

Quality requirements

 Cosmetics There are very high cosmetic requirements for the outer surface of the housing, since this surface is representing the device to the user and potential customer. For the inside surface on the other hand there are minimal requirements in cosmetics. Smooth and high gloss surfaces are often difficult to produce. Whenever possible a flat finish with a texture should be considered as this tends to hide some of these problems. This is done during mould design for the Asclepion housing. Furthermore, the thermoformed housing is coated afterwards with varnish, which gives the opportunity to improve and define the surface to some extent.

 Optics There are no demands towards the optical quality for the main polymer housing. Only in case the laser warning lamp is integrated into the coloured band feature later on, there is the demand for the PMMA band to be transparent.

 Dimensional Tolerances The tolerances can also be estimated with the rule of thumb for designer, discussed on page 14. Calculated regarding the scheme shown in Table 2, the tolerances in production for the top module of the “TattooStarPICO” are 2.28 mm.

49 5.3.2 Ventilation On the strength of past experiences in the development of laser devices at Asclepion, the importance of an efficient ventilation system integrated into the device became apparent. Since the developed design is modular for a whole product family and may be extended or applied to other devices later on, it is important that the design of the ventilation holes can be adapted to different intensities of ventilation. Especially high intense ventilation has to be facilitated by providing enough ventilation area. The inlet and outlet of the air has to be on different walls of the machine. For example, on the side wall and the back wall. Furthermore, the ventilation area in the housing (in form of holes) has to be at least as big as the area of the cooling unit itself. (Schubert, 2015) Below in Figure 50, the present ventilation area is shown in comparison to the new design for “TattooStarPICO”.

Figure 50. Ventilation left: present design (“TattooStar”), right: new design (“TattooStarPICO”) As mentioned, the required ventilation area in the side panel is dependent on the size of the cooling unit. One cooling unit is planned to be used for the “TattooStarPICO”. The size of it is 10 inch, which implies a diagonal length of 254 mm. The area of the cooling unit and thereby the required ventilation adds up to 32 258 mm². The corresponding calculations for those and the following results are shown in the APPENDIX. With the help of data, compiled through the Solid Edge measure tool, the provided ventilation area for the new devices of the product family is calculated. For the devices “MCL31 Dermablate” and “MeDioStar NeXT” the area amounts to 78 428 mm². Through its larger length, the ventilation area of the TatooStar PICO is considerably bigger, with 169 429 mm². Concluding, the new metal housing design provides enough ventilation area. If the cooling unit has to be expanded during development, the housing design still has enough potential to provide the required ventilation area.

The holes which cover the whole side panel represent one drawback of the design, since they make it vulnerable to dust. Also the holes in the cut-out of the logo are too big for the electrical safety test. Protection against accidental contact with inside components would not be given. As a solution for safety, an extra mesh is mounted behind the side panel to protect against accidental contact. Also a mat of fibres is implemented to additionally prevent the ingress of dust.

50 5.3.3 EMC compatible design The thesis project was only about the development of a thermoformed housing without the inner components. For this reason, only the design guidelines for shielding of a device, see 2.3 EMC (Electromagnetic compatibility), had to be considered during the design process. A simplified metal case with ventilation holes to enclose the inner components has been designed additionally.

The housing design is realized as an attachment of front and top modules to the metal housing as it is described in chapter 3.4.2 Modularisation. As it is implemented as a closed metal box, the need of conductive coating for the thermoformed housing becomes no longer necessary. Important for the electromagnetic compatibility of the metal case is to ensure that separate panels are well bonded along their seams, which is provided by the use of conductive gaskets. The diagonal of any opening has to be smaller than 5 cm. (Schubert, 2015) Appling this rule, the big ventilation holes in the side panel, especially of the logo, cause problems. Therefore, the side panels are covered with a metal mesh from the inside as another measure for electromagnetic compatibility.

5.3.4 Laser safety measures The lasers built by Asclepion are belonging to class 4 “High-power lasers”. Like touched in chapter 2.2.3 Laser Safety, the beam of high power lasers or just specular reflections and diffuse reflection are all ocular hazards. Direct and specular reflections are also hazardous to the skin. Some Class 4 lasers are capable of igniting flammable materials. The in chapter 2.2.3 Laser Safety named measured for safety has to be followed using laser devices like those of Asclepion. Furthermore, safety measures are integrated into the housing design. The necessity of a key to start the laser device prevents unauthorised access and also accidental start-up of the machine. The laser warning lamp, indicating an active laser, is only shown on the display for present devices. For the new housing the laser warning lamp will be integrated into the housing. Another important safety feature is the emergency stop button.

5.4 User handling In order to improve the user-friendliness of the devices, some design features have been introduced.

Detachable Elastomer Mat: The housing design is providing a detachable elastomer mat on top of the device. This provides a storage area for medical accessories, like e.g. disinfectant, creams or cool pads. The elastomer mat ensures slip resistance and easy clean ability. The mat has an opening for the mirror joint arm and adjacent a slot, to be able to bend the elastomer mat around the arm for assembly and disassembly. Thereby the device can also be used without the mat, or the polymer mat can be cleaned separately.

Supporting Arm: One disruptive factor named in the customer survey by the interviewees, is the inflexibility of the hand piece hose on the device “MeDioStar NeXT” like mentioned in 3.2.2 Customer Survey. A mechanism was conceived to support the heavy hose of the hand piece. A rough CAD-model of this idea is shown in Figure 51 below.

Figure 51. Hand piece supporting arm The concept behind this idea is to construct two pivotal points. One inside of the base underneath the horizontal cylinder, which provides the rotation around the y-axis. The other pivot is located inside of the horizontal cylinder, to enable tilting of the support arm around x-axis towards the patient. Thereby the support arm is aided by a spring to ensure automatic tilt back.

Display: A bigger display and the introduction of a touch display for the new device “TattooStarPICO”, increase user friendliness compared to the old device. The operator has to be able to read the display during treatment from different angles. Therefore, a well-chosen display angle and a great viewing angle stability of the display are important to be able to operate the device both, upright and sitting. For this part of the design, deeper investigations about the perfect screen angle for the new housing are desirable!

Besides those named features, an additional handle on the backside is planned to provide handles on both sides of the device for transport. Furthermore, a cable take-up stand on the backside will be implemented like it is already done for another device of the company. With this, the cable of the food pedal can be prevented of being overran by the wheels.

5.5 Assembly/ Disassembly Sometimes a product like a laser device requires maintenance of inside components and also pre- tests are performed during manufacturing. For this reason, it is important to facilitate an easy assembly and especially disassembly of the housing.

The disassembly of the developed modular housing is described in the following. First of all, the polymer mat has to be detached. The mat is only inserted and can be separated from the mirror joint arm with the help of a small slit (right picture in Figure 52). Afterwards, the top module can be lifted off from the metal case and above the mirror joint arm due to the big opening in the middle of the module, shown on the right picture in Figure 52. Thereafter. the metal side panels can be disassembled from the metal frame to get access to the inside component of the device. They either slid back on rails, or can be unscrewed and removed. Now the mandrels which fixate the front modules onto the metal case can be unscrewed and the front modules will be detached.

Figure 52. Polymer mat and top module The display is assembled onto the metal housing underneath the top module. In this way, the device can be operated without the housing, which is important for maintenance and pre-tests in manufacturing.

5.6 Materials In the following chapter, the material selection for the different parts of the polymer housing is explained.

Polymer Housing: The housings of the present devices are made of impact resistant Styrene butadiene with flame- retardant (SB V0). The abbreviation V0 specifies the fire rating of the Polymer. Other opportunities for suitable materials according to D. Bitai are flame retardant Acrylonitrile butadiene styrene (ABS) as well as flame retardant and high impact Polystryrol (HIPS V0). Important qualities of the polymer available for selection are impact strength and flame retardancy. The flame retardant also provides for better flow characteristics of the polymer during thermoforming. (Bitai, 2016) Flame retardant ABS would be chosen for the designed housing. Despite the fact of slightly higher costs for the polymer, it has a higher impact strength than the Styrene butadiene and is easier to varnish in post processing. (Bitai, 2016)

Detachable Elastomer Mat: For the detachable elastomer mat a flexible and rubber like material is sought. Under consideration are thermoset rubber materials and thermoplastic elastomers (TPE). Thermoplastic elastomers can be described as thermoplastics with an elastomeric component that makes them soft and flexible. (Mexichem, 2016) They have some advantages over thermoset rubbers. The processing of TPE is simpler, with fewer steps since TPEs are using the processing methods for thermoplastics, which are typically more efficient and significantly less costly. Furthermore, Drobny (2014) mentions that the design freedom is bigger, since TPE can be co- moulded and over moulded. TPE has also shorter fabrication times, which also lead to lower finished part costs. Moreover, TPE offers the possibility of reusing scrap in the same way as with thermoplastics. The scrap from thermoset rubbers is very often wasted. (Drobny, 2014) On this account TPE materials seem to be suitable for the production of a detachable elastomer mat. To choose the correct TPE, questions have to be asked about e.g. the cost target, temperature requirements, exposure to environmental conditions and physical property requirements, like for each other material selection process. (RTP Company, 2015) Presently, the supplied elastomer mats for the devices for Asclepion are made of silicon, which is processed with “Reaction Injection Moulding” (RIM). This would be a second opportunity to produce the new designed elastomer mat.

53 Coloured Band: For production of the coloured band on top of the housing the use of PMMA is intended. The colour can be either realized by colouring the polymer batch before production or after by painting the finished band with RAL colour standard.

5.7 Production The polymer housing is produced at the company “BWF Thermoforms”, based in Geretsried, Germany. The early involvement and cooperation with this thermoform specialist made it possible to deliver a production ready housing design at the end of the thesis project. A visit of the company gave a great insight into production processes at first hand. In the following the production of the three parts of the housing is described.

Polymer Housing: For the production of the housing modules, a cut sheet shuttle machine, like described in chapter 2.1.1 Process, is used. First of all, a decision has to be taken about the sheet dimensions. For the thermoforming process with a cavity mould a lot of material has to be provided circumferential. A rule of thumb is to add the value of the draw depth circumferential to the part size. (Bitai, 2016) This is shown in Figure 53 below. The draw depth is 144.0 mm, like illustrated in the top picture. This leads to a sheet size of 1367.9 mm by 652.0 mm, like shown in the lower picture. The sheet thickness is dimensioned to be around 6 to 7 mm. (Bitai, 2016)

Figure 53. Dimensioning sheet size

54 This single cut sheet is loaded into the process and heated to its forming temperature. The sheet is stretched into the desired shape with the help of mechanical force from a plug assist and vacuum, applied trough some holes in the aluminium tool. With the mould contacting the sheet, the cooling process is initiated. The shaped part is unloaded from the process.

As a first post processing step, the formed part is trimmed to its final shape, by cutting away and bevelling the clamping edge which is process related. The part is then fixed into the CNC-machine, where the material edges are chamfered and marks for the mandrels are pre-milled. In this step also holes have to be drilled into the recesses of the laser warning lamp feature. It will be slightly complicated to drill those holes, in order to insert LED lamps, since the relative recess above prevents the drill reaching the surface in a 90° angle. Thereafter, the part is manually cleaned and deburred. Gloss coating is applied afterwards. In the next step mandrels are glued onto the pre-milled marks, to be able to mount the polymer housing onto the metal case later on. If necessary, the last step is the internal conductive coating. This step is probably not desired for the designed housing, since there is a closed metal case engineered.

“BWF Thermoform” is producing regarding the norm DIN 2768 M, which determines, amongst others, the tolerances for production. The tolerances can also be estimated with the rule of thumb for designer, discussed in chapter 2.1.3. Calculated regarding the scheme shown in Table 2, the tolerances in production for the top module of the “TattooStarPICO” are 2.28 mm.

Detachable Elastomer Mat: The Polymer TPE is chosen for the detachable elastomer mat. It is processed into the desired shape by injection moulding.

Coloured band: One option to realize the coloured band on top of the device is to paint it within the painting step after thermoforming. This requires a big amount of masking work and adds more than one additional step to the production process. The second option is to insert a coloured polymer band into the provided recess on top of the module. This option would also allow the use of the coloured band for illuminating features. The second version is chosen for production. For this purpose, PMMA is punched out from a plate.

Figure 54. Production coloured PMMA band

55 To save material and reduce scrap during production, the coloured band, forming ring is divided into four equal pieces for production, like shown in Figure 54 above. Those four pieces are later on painted with the corresponding RAL colour and glued into the ring of the top module.

5.8 Marketing Marketing wise the new design can be considered as an evolutionary development of the existent design with some new and innovative features. The curvature of the front edges is an evolutionary design element, since it is inspired by the round element of the left edge in the current devices (see Figure 2). In the handle the evolutionary approach of the new housing design becomes obvious as well. The design of the present device handle is taken up and developed further. The screen is the central operating unit which is framed by the housing. Moreover, laser warning lamps are an innovative and new element which additionally will differentiate the new device from competitors. Furthermore, the device can be equally used with or without the rubber mat on top, depending on the planned treatment. The ventilation grille itself is a design element with recognition value since it is constructed as a whole point grid integrating the logo of Asclepion. Therefore, the side panel of the device does appear consistent and uncut. A perfect distinguishing feature is the coloured band on top. The type of the device can instantly be allocated without reading the device name on the front or switching the device on.

56 6 DISCUSSION AND CONCLUSION

In this chapter a discussion of the results and the conclusions that have been drawn during the Master of Science thesis are presented.

6.1 Discussion The objective of this Master of Science thesis, to develop a modular housing design for a product family of laser devices, is fulfilled. Building multiple devices from the same housing modules reduces the overall production costs by decreasing tooling costs and decreasing the diversity of parts from suppliers. In addition, the modularisation allows the multiple use of components like the display for several devices, which lowers the costs and effort for parts from suppliers. The designed product is prepared for the polymer processing method thermoforming as requested. Thereby, an active exchange and contact to the supplier “BWF Thermoform” took place, which meant an important support during design development phase. In addition, with the use of thermoforming, the production costs are kept low. Furthermore, the design of a modular housing leads to a standardisation in appearance of the whole product line. Triggering this process of developing a consistent product family design in the company, within a prompt timeframe, is an important achievement of the thesis project. The whole product development process, from pre-studies over ideation, and concept development to the development of a final product ready for production, was executed during the master thesis project.

The cooperation with the company “BWF Thermoform” enabled access to broad competences in the field of thermoforming, which were intensively used to expand the knowledge on that area during the thesis project. Defining the position and role as a designer in the company was an important step and experience in the beginning of the project. Since Asclepion normally commissions external design companies, it was necessary to find shareholders and promotors within the company and understand the company’s structure. New insights and expertise were gained in coordinating with the different departments involved in the process. Extensive pre studies have been performed for the project and thereby experience was accumulated in the application of methods like competitor analysis, customer survey, observational studies and the development of a brand DNA.

A persistency and proactive work approach was crucial to drive the overall process, from the idea over concepts till the final product, against the daily routine with its running processes. Due to new findings during the development process, the implementation of the new design had to be adapted a few times.

Within the master thesis project the chance was given to design a whole product which is planned to be realized at the end. Whereat big freedom within the company was given and good introduction in the beginning provided. Also knowledge was gained within the field of converting a concept into a final product. Some more focus and assistance during the selection processes in the design cycle would have been desirable. The final design was prepared successfully for the production method thermoforming in great collaboration with the company “BWF Thermoform”.

The primary task for the master thesis project was to design only the housing of the laser device. Focus was therefore on the polymer shell, but always in consideration of the interfaces with the inner components of the laser device, like e.g. the ventilation, the display or the emersion point of the laser light. When the housing design was finished, the construction of the inside components was still in a development phase. Therefore, various changes in the design of the components have

57 been done, which made a reengineering of the final housing design trough the design engineering department necessary.

The housing design was promptly revised and brought to a production stage within the company. As a result of the project, the modular housing design, applied to the new product “TattooStarPICO”, will be shown on a specialist trade fair in November 2017.

6.2 Conclusion Within the framework of the present Master of Science thesis a modular housing for a product family of aesthetic medical laser devices is developed. The housing design is optimized for the predetermined polymer processing method thermoforming. During the development process and implementation necessary coordination of the departments is undertaken. Thereby it became obvious that product design, design engineering and production as well as manufacturing are strongly connected and interacted, for which reason exchange between the spheres of competence is essential. For the solution of the given task, the application of project management tools turned out to be exceedingly beneficial. After a revision of the developed product design by a commercial design company the design has been immediately transferred into serial production.

58 7 REFERENCES

Asclepion. (2016). Retrieved August 3, 2016, from Asclepion Laser Technologies: http://www.asclepion.com/ Asclepion. (2016). Products. Retrieved August 3, 2016, from Asclepion Laser Technologies: http://asclepion.com/products/ Bitai, D. (2016, July 22). Telephone Call (Materials, Production, Post Processing). (M. Schubert, Interviewer) Bruder, U. (2015). User's Guide to Plastic- handout version KTH. Munich: Carl Hanser Verlag. D&PS. (2013). UNION MEDICAL - VENUS IV Plus. Retrieved July 3, 2015, from D&PS. Drobny, J. G. (2014). Handbook of Thermoplastic Elastomers (2nd ed.). Burlington: Elsevier Science. Goldberg, D. J. (2013). Laser Dermatology (2nd ed.). Dordrecht: Springer. Gonçalves, M., Cardoso, C., & Badke-Schaub, P. (2014). What inspires designers? Preferences on inspirational approaches during idea generation. In Design Studies (Vol. 35 (1), pp. 29-53). Gonschorek, K.-H., & Vick, R. (2009). Electromagnetic Compatibility for Device Design and System Integration. Berlin Heidelberg: Springer. HelloTrade. (n.d.). MedArt - FRx. Retrieved July 2, 2015, from HelloTrade_Optical, Laser Instruments & Devices: http://www.hellotrade.com/energist-group-usa/medart-frx- fractional-co2-laser.html Inc, A. A. (2015). Hoya - ConBio RevLite. Retrieved July 2, 2015, from Allure Aesthetics Inc: http://allureaestheticsinc.com/lasers-for-sale/hoya-con-bio/hoya-con-bio-revlite-sale/ Ingle, B. R. (2013). Design Thinking for Entrepreneurs and Small Businesses. Apress. Kang, N., & Suto, H. (2013). How to Observe, Share and Apply in Design Process? In A. Marcus, Design, User Experience, and Usability. Design Philosophy, Methods, and Tools (pp. 498- 505). Berlin Heidelberg: Springer. Klein, P. (2009). Fundamentals of Plastics Thermoforming. Morgan & Claypool Publishers. Lanigan, S. W. (2000). Lasers in Dermatology. London: Springer. Lanigan, S. W. (2000). Lasers in Dermatology. London: Springer-Verlag. Lasers, A. (2015). Alma Lasers_Soprano ICE. Retrieved 07 21, 2016, from Alma Lasers_Soprano ICE Hair Removal: http://almalasers.com/us/ice Lasers, O. (2016). Alma Lasers_Sinon. Retrieved 07 21, 2016, from Oscilla Lasers_Sinon: http://oscillalasers.com/shop/sinon-694-nm-q-switched-ruby/ LiveGorgeousOC. (2015). Alma Lasers - Accent XL. Retrieved July 3, 2015, from LiveGorgeousOC: http://www.livegorgeousoc.com/services/ Lo, C.-H., Tseng, K. C., & Chu, C.-H. (2010). One-Step QFD based 3D morphological charts for concept generation of. Expert Systems with Applications, 37, 7351-7363. Luthra, V. (2016). corporate identity. Retrieved 07 29, 2016, from BusinessDictionary: http://www.businessdictionary.com/definition/corporate-identity.html MedicalEXPO. (2016). Products_Union Medical. Retrieved from MedicalEXPO: http://www.medicalexpo.com/prod/union-medical/product-70411-611321.html

59 MedicalEXPO_Alexandrite. (2016). Quanta System - Q Plus A. Retrieved from MedicalEXPO_Alexandrite Lasers. MedicalEXPO_Products. (2016). UNION MEDICAL - HERA XP. Retrieved July 3, 2015, from MedicalEXPO_Products: http://www.medicalexpo.com/prod/union-medical/product- 70411-611321.html MedWOW. (2014). Lutronic - Spectra. Retrieved July 3, 2015, from MedWOW_Medical Equipement: http://www.medwow.com/med/vascular-lesion-removal- laser/lutronic/spectra-dual/68657.model-spec Mexichem. (2016, April 22). Home / Blog / TPE Compounds are the right touch for many products. Retrieved July 06, 2016, from Mexichem Specialty Compounds: http://www.mexichemspecialtycompounds.com/Blog/TPE-Compounds-are-the-right- touch-for-many-products/3215 RTP Company. (2015). Choosing the Correct TPE. Retrieved July 2, 2016, from RTP Company: http://www.rtpcompany.com/products/elastomer/choosing-the-correct-tpe/ Schubert, M. (2015, March 4th). Notes taken at the Asclepion meeting on "Requirements towards design". Jena, Germany: Maxi Schubert. Shetty, D. (2015). Product Design for Engineers. Boston: Cengage Learning. Subramanian, M. N. (2011). Basics of Troubleshooting in Plastics Processing: An Introductory Practical Guide. Scrivener Publishing LLC. System., R. M. (n.d.). IDS Lasers - Surgical Laser Machine. Retrieved July 2, 2015, from Ronak Medical System.: http://www.indiamart.com/v-care-meditech/surgical-laser-machine.html TATAWAY. (2016). Cynosure - PicoSure Laser. Retrieved July 2, 2015, from TATAWAY: http://tataway.com/picosure-laser/ Verwijderen, T. (2014, December 11). Syneron Candela - PicoWay laser. Retrieved July 2, 2015, from Tatoeage Verwijderen: http://www.tatoeageverwijderen.com/techniek/laser/picoway-laser-tatoeage- verwijdering-informatie/ WikID, T. (2016). Morphological chart. Retrieved 07 23, 2016, from The Industrial Design Engineering Wiki: http://www.wikid.eu/index.php/Morphological_chart Williams, T. (2007). EMC for Product Designers (4th ed.). Burlington: Elsevier Science.

60 APPENDIX

Questionnaire Operator Convenience

Created: Vs. Description Modification Date Name

01 First version 2015-03-05 M. Schubert

Name (optional):………………………………… Country:………………………………………… Date: ………………………………………

Which devices do you use? (Please tick boxes) Dermablate TatooStar MeDioStar QuadroStar MCL31 TattooStar Effect Effect Dermablate a b c d e f

(If the answer for the following questions is not the same for all devices, please specify by writing the corresponding device-letter beside the ticked box)

What do you think about the size of the display? to small exactly right to big

What do you prefer regarding the touch-screen operation? more complex simple & fast (possibility to show videos, save patient data, show example pictures)

Our devices have a fixed display. Would you be willing to pay more money for a movable display? Yes No Not sure

Are the ergonomic properties of the device satisfying? (Device shape, number of handles, height of handle, storage area, …) Yes No If No, what disturbs you?

In which position do you preferably operate the device? sitting upright both

Is the device manoeuvrable and easy to move? Yes No If No, what causes problems?

Comments for Improvements:

61 Drawing

Concept 1

647,2 223

4 53,62

1 °

5 4 6

365 560

All values in mm

62 Calculation ventilation area for product family

Calculation of required ventilation area:

Given: Size of cooling unit:  10``= 254 mm 푎

푎

Side length a:

푙 254 푚푚 푎 = = = 179.61 푚푚 √2 √2

Area cooling unit A:

퐴 = 푎² = (127 √2)² = 32,258 푚푚²

 Required ventilation area: 32,258 mm²

Calculation of provided ventilation area: Given:

Hole: r = 3 mm 푟 – Radius 푁 – Number of holes 퐴ℎ– Surface area of one hole 퐴퐴– Surface area of all holes 퐴푉– Provided ventilation area

Surface area one hole:

2 2 퐴ℎ = 휋푟 = 휋푟 (3 푚푚) = 28.27 푚푚²

63 Surface area all holes:

TatooStar PICO MCL31 Dermablate & MeDioStar NeXT

2 2 퐴퐴 = 푁퐴ℎ = (76 ∙ 90) ∙ 28.27 푚푚 퐴퐴 = 푁퐴ℎ = (51 ∙ 71) ∙ 28.27 푚푚 = 193,367 푚푚² = 102,366 푚푚²

Surface area logo (cut-out character):

2 퐴1 = 319 ∙ 28.27 푚푚 = 9018.13 푚푚²

Surface area extrusion logo (frame character):

2 퐴2 = 139 ∙ 28.27 푚푚 = 3929.53 푚푚²

Surface area extrusion logo (Asclepion spots):

퐴3 = 10990.10 푚푚²

Provided ventilation area:

TatooStar PICO MCL31 Dermablate & MeDioStar NeXT

2 2 2 2 퐴푉 = 193,367 푚푚 − 9018,13 푚푚 퐴푉 = 102,366 푚푚 − 9018,13 푚푚 −3929.53 푚푚2 + 10990.10 푚푚2 −3929.53 푚푚2 + 10990.10 푚푚2

퐴푉 = ퟏퟔퟗ, ퟒퟐퟗ 풎풎² 퐴푉 = ퟕퟖ, ퟒퟐퟖ 풎풎²

64 Engineering drawings

Top module

65 Front top module

66 Front bottom module