Stock shapes

Machining Recommendations for Semi-Finished Engineering Plastics Content

4 Processing of plastics (introduction) 5 Differences between plastics and metals 6 Extrusion technology 6 Tools and machines

7 Machining 8 Cutting 9 Turning 9 Milling 10 Drilling 11 Cutting threads 11 Planing / Plane milling 12 Grinding 13 Surface quality, reworking and de-burring 15 Machining guidelines

16 Interview with Hufschmied Zerspanungssysteme

18 Cooling and cooling lubricants

19 Annealing 20 Morphological changes and post-shrinkage 21 Dimensional stability

22 Product groups and material characteristics 22 TECAFORM AH / AD, TECAPET, TECAPEEK 22 TECAST T, TECAMID 6, TECAMID 66 23 TECANAT, TECASON, TECAPEI 23 TECA Materials with PTFE 23 TECASINT 24 Fibre reinforced materials 25 Special case of TECATEC

26 Machining errors - causes and solutions 26 Cutting and sawing 26 Turning and milling 27 Drilling Technical plastics

PI High-temperature 300 °C plastics PAI PEKEKK PEEK, PEK LCP, PPS PES, PPSU PTFE, PFA PEI, PSU ETFE, PCTFE 150 °C PPP, PC-HT PVDF

Engineering plastics PA 46 PC 100 °C PET, PBT PA 6-3-T PA 66 PA 6, PA 11, PA 12 POM PMP Long term service temperature Standard plastics PPE mod.

PMMA PP

PE PS, ABS, SAN

Amorphous

Semi-crystalline

Polymer Abbreviation Ensinger Nomenclature Polymer Name PI TECASINT PEEK TECAPEEK PPS TECATRON Polyphenylene sulphide PPSU TECASON P Polyphenylsulphone PES TECASON E Polyethersulphone PEI TECAPEI Polyetherimide PSU TECASON S Polysulphone PTFE TECAFLON PTFE Polytetrafluoroethylene PVDF TECAFLON PVDF Polyvinylidene fluoride PA 6 C TECAST T 6 cast PA 66 TECAMID 66 Polyamide 66 PA 6 TECAMID 6 Polyamide 6 PC TECANAT Polycabonate PBT TECADUR PBT Polybutylene terephthalate PET TECAPET Polyethylene terephthalate PPE TECANYL Polyphenylene ether POM-C TECAFORM AH Copolymer POM-H TECAFORM AD Polyoxymethylene Homopolymer PMP TECAFINE PMP Polymethylpentene Processing of plastics

Dimensionally stable, functional and durable components The specific properties of plastics have a decisive influence can be manufactured from plastics using professional upon their machining ability. Materials can be classified machining and processing techniques. The general term into different groups: “Plastic Processing” suggests that all plastics can be ˌˌAmorphous machined with the same parameters and tools. With metals, (e.g.: TECASON S, TECANAT) on the other hand, one speaks not only of “metal process- ˌˌPartly crystalline thermoplastics ing”, but a difference is made between aluminium, steel or (e.g.: TECAFORM, TECAPET, TECAPEEK) stainless steel. In an analogous way, it applies that the ˌˌFibre reinforced thermoplastics individual characteristics of plastic materials have to be (e.g.: TECAPEEK PVX, TECAMID 6 GF 30, taken into consideration when processing them. TECAMID 66 CF20, TECADUR PBT GF 30) ˌˌFabric reinforced thermoplastics (e.g.: TECATEC PEEK CW 50) ˌˌPTFE modified thermoplastics (e.g.: TECAPET TF, TECAPEEK TF10 blue)

4 Differences between plastics and metal

Compared to metals, plastics have a wide range of benefits to offer, although a number of restrictions must also be borne in mind. Basically, the use of plastics is possible in those areas where in particular a favourable ratio between weight and strength is required.

Plastic offers a solution for applications calling for two to three of the following characteristic benefits. However, in order to be able to utilise the benefits of plastics when sub- stituting other materials, the component may also have to be redesigned. p Benefits over metal ˌˌLow density ˌˌGood noise and vibration damping ˌˌElectrical insulation or adjustable conductivity ˌˌGood chemical resistance ˌˌScope for free design s Possible consequences, if not observed ˌˌPermeability to electromagnetic waves ˌˌToo much heat input in the component can lead to high ˌˌVery good corrosion resistance stress levels and thus to warping or fracture. ˌˌThermal insulation ˌˌExcessive heat input causes expansion of the plastic. ˌˌApplication-specific modification possible The required tolerances of machined parts can thus not be maintained q Limitations compared to metal ˌˌInadequate fixation may lead to deformation during ˌˌRelatively low thermal resistance machining ˌˌGreater thermal expansion ˌˌLower mechanical characteristics u Recommendations ˌˌPoorer creep resistance ˌˌGood heat dissipation - best via the material chips - as well as adequate fixation The above mentioned advantages and disadvantages of plastics compared to metals are to be observed especially in This approach needs to be adapted depending on the processes involving technical machining. plastic, in order to establish the optimum cutting tools and parameters for all materials. Only in this way s To be noted: can optimum components be made. Detailed information ˌˌGood thermal insulation on the machining of plastic materials is available on the ˌˌLower thermal conductivity following pages. ˌˌHeat is not or only partly dissipated via the machined component, as in metal processing ˌˌHigher thermal expansion than metals ˌˌGood fixation and support of plastics in processing

5 What role does extrusion Tools and machines for technology play in processing plastics machining?

Manufacturing processes, especially the extrusion of semi- For the machine processing of plastics/semi-finished finished goods, have an impact on the properties and the goods, normal commercially available machines from the workability of a material. wood and metal working industries can be used with tools made of high-speed steel (HSS). Plastic semi-finished goods made of PTFE or can be manufactured by compression and sintering. An In principle tools with cutting edge angles like those used important processing technology for other thermoplastics with aluminium are suitable. But we recommend the use is the extrusion process. In this shaping process, materials of special tools for plastic with sharper wedge angle. are melted and compressed in a cylinder via a screw conveyor and homogenised. Using the pressure arising in the cylin- Hardened steel tools should not be used for processing re- der – and the appropriate tooling – semi-finished goods are inforced plastics, due to the low holding times and the long delivered in the form of sheets, round rods and tubes and processing times. In this case, the use of tungsten carbide, calibrated via a cooling system. ceramic or diamond-tipped tools is advisable. Similarly, cir- cular saws fitted with carbide tipped saw blades are ideal for Impact cutting plastics. ˌˌInternal tension develops ˌˌFibres take up a specific orientation (if available) u Recommendations ˌˌUse tools which are specific for plastics Ensinger offers a broad product portfolio of semi-finished ˌˌHave a suitable cutting geometry engineering plastics and high-temperature plastics. Stand- ˌˌVery well sharpened tools ard plastic materials round off the portfolio. All these ma- terials are manufactured so they may be processed opti- mally by machining.

Internal tension The resulting pressure in the extrusion process produces a shear movement and flow of the plastic molten mass. The semi-finished goods discharged by the tool slowly cool from the marginal layer to the centre. The poor thermal conductivity of plastics results in different cooling rates. Whereas the margins have already solidified, the centre still contains plastic in the liquid state or fused plastic. Plas- tics are subject to a typical shrinkage pattern for that mate- rial. During the cooling phase, the plastic centre is hin- dered from contracting by the rigid boundary layer.

Impact of the technological process ˌˌInternal stresses (in the centre) are due to the technological process ˌˌSemi-finished products are difficult to machine hh High risk of tearing and fractures Cooling takes place from the outside

Possible solutions � Material-specific annealing to minimise stresses Centre: (� p. 19) Stress peaks

6 Machining

Machining (defined according to DIN 8580) is the fastest and most economic way to produce precise components, es- pecially in small volumes. Very narrow tolerances can be achieved using machining procedures.

Ensinger itself has decades of experience in the field of ma- chine processing of engineering and high-temperature plastics. This know-how allows us to produce highly pre- cise components made of different plastics using in-house machining. Furthermore, we shall be pleased to support you with processing information about the machining and further processing of our semi-finished goods or pre-pro- duced products using or direct forming processes.

7 Cutting

Circular saws ˌˌMainly suited for cutting plates to size with straight cutting edges ˌˌTable circular saws can be used with the right power drive for straight cuts of plates with thicknesses of up to 100 mm ˌˌSaw blades should be made of hardened metal ˌˌUse a sufficiently high enough feed rate and adequate offset hh Leads to good chip deflection hhAvoids sticking of the saw blade hhAvoids overheating of the plastic in the saw cut hhLeads to good cutting edge quality

u Recommendations ˌˌUse a corresponding tensioning device: hhAvoidance of vibrations and unclean cutting edges What sawing processes are best suited to cut plastic parts? which can result from this, or even lead to breakage Plastics can be cut using a band saw or a circular saw. The ˌˌWarm cutting of very hard and fibre-reinforced choice depends on the shape of the stock shape. Generally materials (pre-heat to 80 – 120 °C) speaking, heat generated by the tooling when processing ˌˌTungsten carbide saw blades wear well and provide an plastics and hence damage to the material is the greatest optimum surface finish danger. For this reason, the right saw blade must be used for every shape and material.

Sägen Band saws Most suitable for cutting to size round rods and tubes t ˌˌ α ˌˌIt is recommended that support wedges are used γ α Clearance angle [°] ˌˌSharp and sufficiently set saw blades should be used γ Rake angle [°] hhGood chip removal t Pitch [mm] hh Avoidance of high friction between the saw blade and material as well as excessive thermal build-up hhAvoids saw blade blocking p Advantage: ˌˌHeat generated by sawing is well dissipated thanks to BohrenKey facts at a glance the long saw blade β ˌˌBand saws allow versatile application for straight, Ensure that set, sharp saw blades are used γ continuous or irregular cuts when sawing plastics. φ ˌˌProduces a good cutting edge quality α φ

Fräsen α

γ

8

Drehen

α χ γ How are plastics best Milling recommendations processed on a lathe? (turning)

Plastics can be processed on commercially available lathes. Plastics can be milled using customary machining centres. For optimal results, however, specific plastic cutters should This should be done using tools with adequate chip space be used. in order to guarantee reliable discharge of chips and prevent overheating. Cutting tools ˌˌUse tools with small cutting radii Tools ˌˌBroad-nosed cutting edge for high quality ˌˌSuitable for thermoplastics finish requirements hhSlot milling cutter ˌˌKnifelike cutting geometries for machining flexible hhFace milling cutter workpieces hhCylindrical milling cutter ˌˌUse favourable geometries for fixing hhSingle cutter tools ˌˌSpecial chisel geometry for parting off hhFly cutter ˌˌCut circumferences and polished surfaces ˌˌSingle cutter tools p Advantage: p Advantage: ˌˌOptimal, groove-less surface hhOptimal average high cutting performance ˌˌReduces the build-up of material on the application hhHigh surface quality with good chip removal at the same time u Recommendations ˌˌSelect a high cutting speed u Recommendations ˌˌUse a cutting depth of at least 0.5 mm ˌˌHigh cutting speeds and medium feed rates ˌˌCompressed air is well suited for cooling ˌˌEnsure good attachment: ˌˌUse of a lunette due to reduced rigidity of plastics hhRapid method for the table and a high spindle speed hhStabilise the component coupled with correct fixture alignment lead to higher hhAvoidance of deformation quality machined finish p Advantage: ˌˌThin work-pieces can be secured using a suction fixture ˌˌGood cooling of the material or dual-sided adhesive tape on the router table ˌˌOvercomes flow chipping which can arise with some ˌˌFor flat surfaces, end milling is more economical than plastics. Prevents jamming and rotating with the lathe peripheral milling part of the blade ˌˌDuring peripheral milling, tools should not have more than two cutting edges in order to minimize vibrations caused by a high number of cutting edges, and chip spaces should be adequately dimensioned Polished section avoids scrap How better milling surfaces can be achieved ˌˌFor surface milling, choose a low chip angle ˌˌOptimal cutting performance and surface qualities result from single cutter tools Trimming Cutting chisel ˌˌDown milling should be used in preference to conventional milling

9 Drilling engineering plastics

When drilling plastic components, select a method suitable u Recommendations for drilling for plastic materials in order to avoid defects. Otherwise, small diameter holes ( < 25 mm) there is a danger of breaking, tearing, overheating or ˌˌUse of high-speed steel drills (HSS drills) dimensional deviations of the drill holes. ˌˌUse a spiral drill ˌˌTwist angle of 12 – 25°: When drilling, particular attention must be paid to the hh Very smooth spiral grooves insulating characteristics of plastic. These can cause plas- hhFavours chip deflection tics (especially semi-crystalline ones) to quickly build up ˌˌFrequent removal of the drill (intermittent drilling) heat during the drilling process, particularly if the drilling hh Better removal of the chips and avoidance of thermal depth is more than twice the diameter. This can lead to build-up “smearing” of the drill and an inner expansion arising in ˌˌIn the case of thin-walled components it is the component, which can lead to compressive stress in the recommended to use: part (especially when drilling into the centre of round rod hhHigh cutting rates sections). The stress levels can be high enough to cause a hhIf possible, select a neutral (0°) chipping angle in high level of warping, dimensional inaccuracy, or even order to avoid drill catching in the component and cracks, fractures and bursting open of the finished compo- thus tearing of the drill and/or lifting of the work- nent or blank. Appropriate processing for the material will piece by the drill prevent this. u Recommendations for drilling large diameter holes ( > 25 mm) ˌˌCarry out a trial drilling with large drill holes ˌˌSelect a pre-drilling diameter which is no larger than 25 mm Stress curve Stress curve ˌˌCarry out finishing subsequently with an inner cutting in blunt drill in sharp drill chisel ˌˌIntroduce drilling into long rod sections only from Tools one side ˌˌWell-sharpened commercially available HSS drills are hhIn the case of drilling attempts which meet in the normally sufficient middle (bilateral drilling), unfavourable tension ˌˌUse drills with a narrow bridge (synchronised drilling): characteristics may arise, or even tearing hh Reduced friction and avoidance of a build-up of heat ˌˌIn extreme cases/in the case of reinforced materials, it may be advisable to carry out the drilling on a pre- u Recommendations warmed component at approx. 120 °C (heating time ˌˌUse a coolant approx. 1 hour per 10 mm cross-section) ˌˌFrequent withdrawal of the drill: hhTo ensure dimensional accuracy, finish machining hhChip removal then takes place after the blank has cooled down hhAdditional cooling completely ˌˌAvoid the use of a manual feed: hhEnsures that the drill does not become caught hhPrevents cracking Key facts at a glance

Ensure that the drill is sharp. Furthermore, do not exert pressure which is too high.

10 Cutting threads Planing / plane milling

Threads are best introduced into engineering plastics using Planing and plane milling are chip production methods chasing tools for male threads or milling for female threads. with geometrically determined cutting for the manufacture of certain cuts to produce equal surfaces, grooves or pro­ Tools files (using shaping milling). ˌˌUse of a chasing tools ˌˌTwo-dentate chaser avoids burr formation Both procedures differ only in that with planing a straight ˌˌDies are not recommended. In the case of a return, line of material removal is made across the surface using a re-cutting is possible planing machine cutting tool. In the case of plane milling, on the other hand, the surface is processed using a milling u Recommendations head. Both processes are well-suited to produce even and/ ˌˌTaps often have to be provided with an allowance or equalised surfaces on semi-finished goods. The main (dependent upon material and diameter, approx. difference is that optically different surfaces arise (surface value: 0.1 mm) structure, gloss). ˌˌDo not select a pre-setting which is too high, in order to avoid squashing of the thread Planing and plane milling at Ensinger ˌˌEnsinger can offer both planed as well as plane milled semi-finished goods via the cutting to size service ˌˌSheets > 600 mm can only be processed using the plane milling process ˌˌSheets < 600 mm can be processed using both processes ˌˌSmall cuts are processed using planing

Fräshobeln FräshobelnMilled surface HobelnPlaned surfaceHobeln

Plane milling Planing

11 Grinding Sägen Hobeln

In grinding, the overall effect of cutting, work-piece, deliv- Optimally adjusted machinery and the right choice of pa- ery and feed movements results in a continuous chip re- rameters for the corresponding material ensure that very moval from the surface being processed. The grinding re- good surface quality with slight roughness diameter toler- sult is influenced by ances up to h9, roundness and straightness can be ˌˌthe grinding machine achieved. ˌˌthe tool being used ˌˌthe grinding medium Grinding at Ensinger ˌˌthe working parameters of the grinding process We are able to provide ground round rods via our cutting ˌˌthe material to be processed service. Thanks to a high surface quality and narrow toler- ˌˌthe roundness/straightness of the semi-finished goods ances, ground round rods are easily further processed and are suitable for continuous production processes. Particularly decisive working parameters are: Schleifen Formhobeln ˌˌcutting speed ˌˌforward rate of advance ˌˌdelivery ˌˌcross-sectional advance rate

12 Surface quality, reworking and de-burring

To obtain a good surface quality, the following guidelines Cooling should be followed: ˌˌUse coolants for processes involving the generation of high levels of heat (such as drilling) Tools ˌˌUse suitable coolants ˌˌTools suitable for plastics must be used ˌˌTools must always be well sharpened and smooth u Recommendations (sharpened cutting edge). Blunt cutting edges can lead ˌˌTension pressures must not be too high, as otherwise to increased heat generation, resulting in distortion and deformations and impression marks can result on the thermal expansion work-piece ˌˌTools should be adequately spaced to ensure that only ˌˌSelect suitable parameters for the machining process the cutting edge comes into contact with the plastic (� p. 15) ˌˌKeep feed rate to a moderate level Processing machine ˌˌSelect a high cutting speed ˌˌFlawless, high-quality finished surfaces can only be ˌˌGood removal of chips must be guaranteed in order to achieved with low-vibration machine running prevent tool congestion ˌˌEnsure that chip removal is equal on all sides in order Material to prevent warping ˌˌUse low-tension annealed material (semi-finished goods from Ensinger are generally low-tension annealed) ˌˌNote the properties of the plastic (thermal expansion, low strength, poor heat conduction ... ) ˌˌDue to the minimal rigidity of the material, the work- piece must be adequately supported and lie as flat as possible on the supporting surface in order to avoid deflection and out-of-tolerance results

13 De-burring Typical de-burring methods After milling, grinding, drilling, turning or engraving, a for engineering plastics small piece of the material to be processed remains on the work-piece or its edges. This flash negatively influences the Manual de-burring quality of the surface of the component. In plastics process- ˌˌMost common method of de-burring ing, burr formation depends in particular on a number of ˌˌFlexible, but most work intensive different parameters. ˌˌAt the same time, visual control of the component can be performed Tooling ˌˌSelect tooling which is specific for a particular material Jet de-burring ˌˌCondition of the tool: Jet of abrasive material at high pressure used on the surface hh Blunt tools cause a much higher level of heat of the component; common blasting methods: sand, glass development and burr formation balls, soda, dry-ice and nutshell blasting ˌˌAlso, represents surface treatment methods Material hh Smoothing ˌˌPoor thermally conducting plastics: hhRoughening hhLocal increased temperatures, reduction hhRemoval of contamination of rigidity and hardness hhMelting burrs/flash Cryogenic de-burring ˌˌThere is a tendency for soft, tough plastics Removal of burrs at temperatures around –195 °C via the (e.g.: PE, PTFE) to show more burr formation; hard, use of a jet or drum tumbling of the components stiffer materials (e.g.: PEEK, PPS, fibre-reinforced ˌˌFrequent coolants: liquid oxygen, liquid carbon dioxide, material) less dry-ice ˌˌLow temperatures lead to brittleness and hardness of Processing parameters the materials ˌˌMaterial advancement rate ˌˌCutting speed: Flame de-burring hhHigher advancement rates and cutting speeds lead to De-burring using an open flame higher temperatures ˌˌDanger: damage may be caused to the component due hhGreater burr formation to excessive heat development ˌˌEnsure adequate cooling Hot-air de-burring For the reasons mentioned, it is important to select a The flash melts under the influence of heat suitable tool for each material and to establish the right ˌˌVery safe and well controllable process parameters, in order to achieve the best possible and flash- ˌˌAvoidance of damage or warping of the component free surfaces and edges. when using process management suitable for the material

Infrared de-burring Process is comparable to hot-air de-burring, instead of hot air, an infrared heat source is used for heating

Rumbling / Trovalising Treating the parts together with abrasives in rotating / ­vibrating

14 Sägen t α

γ Machining guidelines

Sawing Sägen Drilling Bohren β t α Clearance an le [°] α Clearance an le [°] α γ Rake an le [°] β Twist an le [°] t Pitch [mm] γ γ Rake an le [°] γ φ Point an leφ [°] V Cuttin speed [rpm] α S Feed rate [mm/r] φ Sägen

Circular saw Band saw t α

Rotation speed Cuttin speed Number γ Twist Rake Cuttin Feed [rpm] Pitch [m/min] Pitch of teeth an le an le speed rate Fräsen TECAFINE PE/PP 2800 – 3000 31 – 38 130 – 180 11 – 15 Z2 25 90 50 – 150 0.1 – 0.3 Bohren α TECAFINE PMP 2800 – 3000 31 – 38 130 – 180 11 – 15 Z2 25 90 50 – 150 0.1 – 0.3 β γ TECARAN ABS 2600 31 – 38 130 – 180 11 – 15 Z2 25 90 50 – 200 0.2 – 0.3 TECANYL 2800 – 3000 γ 31 – 38 130 – 180 11 – 15 Z2 25 90 50 – 100 0.2 – 0.3 TECAFORM AD/AH 2800 – 3000 31 – 38 130 – 180 11 –φ 15 Z2 25 90 50 – 150 0.1 – 0.3 TECAMID, TECARIM, TECAST 2000 – 2600 31 – 38 130 – 180 11 – 15 Z2 25 90 50 – 150Bohren 0.1 – 0.3 α 2200φ – 2600 31 – 38 130 – 180 Sägen 11 – 15 Z2 25 90 50 – 100 0.2 – 0.3 TECADUR/TECAPET β TECANAT 2400t 31 – 38 130 – 180 11 – 15 Z2 25 90 50 – 100 0.2 – 0.3 α TECAFLON PTFE/PVDF 2800 – 3000 20 – 24 130 – 180 11 – 15 Z2 γ 25 90 150 – 200 0.1 – 0.3 TECAPEI 3000γ 20 – 24 130 – 180 11 – 15 Z2 25 90 20 – 80φDrehen 0.1 – 0.3 TECASON S, P, E 3000 20 – 24 130 – 180 11 – 15 Z2 25 90 20 – 80 0.1 – 0.3 Fräsen α TECATRON 3000 20 – 24 130 – 180 11 – 15 φ Z2 25 90 50 – 200 0.1 – 0.3 α α TECAPEEK 3000 20 – 24 130 – 180 11 – 15 Z2 χ 25 90 50 – 200 0.1 – 0.3 TECATOR 3000 20γ – 24 130 – 180 11 – 15 Z2 25 γ 90 80 – 100 0.02 – 0.1 TECASINT 3000 20 – 24 130 – 180 11 – 15 Z2 25 120 80 – 100 0.02 – 0.1 Reinforced/fi lled TECA products* 2400 – 2800 20 – 24 110 – 150 11 – 15 Z2 25 100 80 – 100Fräsen0.1 – 0.3 Bohren α * Reinforcin a ents/fi llers: Heat before sawing: Heat before drilling in the centre: β Glass fi bres, lass beads, carbon from Ø 60 mm TECAPEEK GF/PVX, TECATRON GF/PVX from Ø 60 mm TECAPEEK GF/PVX, TECATRON GF/PVX γ fi bres, raphite, mica, talcum, etc. from Ø 80 mm TECAMID 66 GF, TECAPET, TECADUR PBT GF from Ø 80 mm TECAMID 66 MH, 66 GF, TECAPET, TECADUR PBT GF from Ø 100 mmγ TECAMID 6 GF, 66, 66 MH from Ø 100 mm TECAMID 6 GF, 66, TECAM 6 MO, TECANYL GF φ Recommendation Diameter of circular saw blade = 450 – 480 mm Drehen α Circularφ saw tooth type = Alternating teeth Circular saw blades from hard metal. For reinforced materials a dia- mond-studded sawing blade is recommended for better tool life. Band saw blades αfrom hard metal, well set. χ γ Milling Turning Drehen α Clearance an le [°] Fräsen α Clearance an le [°] α γ Rake an le [°] γ Rake an le [°] V Cuttin speed [rpm] χ Side an le [°] γ S Feed rate [mm/r] α V Cuttin speed [rpm] χ Tan ential feed S Feed rate [mm/r] Feed rate can be up γ The nose radius r to 0,5 mm / tooth must be at least 0,5 mm

Number Cuttin Feed Clearance Rake Side Cuttin Feed of teeth speed rate an le an le an le speed rate TECAFINE PE, PP Z2 – Z4 250 – 500 0.1 – 0.45 6 – 10 0 – 5 45 – 60 250 – 500 0.1 – 0.5 TECAFINE PMP Z2 – Z4 250 – 500 0.1 – 0.45 6 – 10 0 – 5 45 – 60 250 – 500 0.1 – 0.5 Drehen TECARAN ABS Z2 – Z4 300 – 500 0.1 – 0.45 5 – 15 25 – 30 15 200 – 500 0.2 – 0.5 TECANYL Z2 – Z4 300 0.15 – 0.5 5 – 10 6 – 8 45 – 60 300 0.1 – 0.5 TECAFORM AD, AH Z2 – Z4 300 0.15 – 0.5 6 – 8 0 – 5 45 – 60 300 – 600 0.1 – 0.4 α TECAMID, TECARIM, TECAST Z2χ – Z4 250 – 500 0.1 – 0.45 6 – 10 0 – 5 45 – 60 250 – 500 0.1 – 0.5 TECADUR/TECAPET Z2 – Z4 γ 300 0.15 – 0.5 5 – 10 0 – 5 45 – 60 300 – 400 0.2 – 0.4 TECANAT Z2 – Z4 300 0.15 – 0.4 5 – 10 6 – 8 45 – 60 300 0.1 – 0.5 TECAFLON PTFE, PVDF Z2 – Z4 150 – 500 0.1 – 0.45 5 – 10 5 – 8 10 150 – 500 0.1 – 0.3 TECAPEI Z2 – Z4 250 – 500 0.1 – 0.45 10 0 45 – 60 350 – 400 0.1 – 0.3 TECASON S, P, E Z2 – Z4 250 – 500 0.1 – 0.45 6 0 45 – 60 350 – 400 0.1 – 0.3 TECATRON Z2 – Z4 250 – 500 0.1 – 0.45 6 0 – 5 45 – 60 250 – 500 0.1 – 0.5 TECAPEEK Z2 – Z4 250 – 500 0.1 – 0.45 6 – 8 0 – 5 45 – 60 250 – 500 0.1 – 0.5 TECATOR Z2 – Z4 60 – 100 0.05 – 0.35 6 – 8 0 – 5 7 – 10 100 – 120 0.05 – 0.08 TECASINT Z2 – Z4 90 – 100 0.05 – 0.35 2 – 5 0 – 5 7 – 10 100 – 120 0.05 – 0.08 Reinforced/fi lled TECA products* Z2 – Z4 80 – 150 0.05 – 0.4 6 – 8 2 – 8 45 – 60 80 – 150 0.1 – 0.5

* Reinforcin a ents/fi llers: Preheat material to 120 °C Glass fi bres, lass beads, carbon Caution when usin coolants: fi bres, raphite, mica, talcum, etc. susceptible to stress crackin

15 Interview: with Hufschmied Zerspanungssysteme

What is the business of the Hufschmied Company? Process development Hufschmied is specialised in the development and manu- facture of “material-optimised machining tools” for the field Material Machine of plastics and composites. Our tooling is manufactured in- house using CNC 6-axis grinding centres. In this way, short throughput times are possible from the enquiry to the deliv- Good / Rotation speed ery. High-grade fully hardened metals and ceramics serve as Tool economic (max. possible) the basic materials, which are coated according to the re- part quirements of the customer.

What is your experience in the field of machining plastics Programming Tool clamping in general? Hufschmied has been present in the market for more than 25 years. Very early on we have concentrated on the ma- chining of plastics, as it was evident that this is where high What philosophy do you follow in plastics processing? growth was to be expected. Plastics continue to develop We always design our plastic tooling for dry machining. It rapidly and new high-tech materials are added to the mar- is relatively seldom that we are able to machine under "wet" ket every day. As we work with different material manu­ conditions: The application or the purpose of the compo- facturers and universities, we always have the possibility to nent often does not allow this. come into contact at a very early stage with novel materials. These are then machined in our own laboratory. In this Additives are included in all coolants and can adverse reac- way, we can support our customers at an early stage with tions during the machining of plastics and additives. Our appropriate tools and processes. tools are designed for machining at high feed rates. High feed rates are used to ensure that there is no temperature How do you react to the new challanges involved with the dissipated into the component, but into the chips. These new materials? parameter adjustments are often made on site, because the To date, we have been able to machine all plastics, even if customer does not want to risk “cutting corners” due to a sometimes several optimization loops were needed for the lack of experience. tooling. Plastics are becoming more diverse, so that we need to adjust the tool geometries accordingly. A material data What do you see as the main problems in the plastics sheet is helpful, especially with "filled" materials. As we do processing market? not manufacture the plastics ourselves and are not able to In my opinion, the customer is still focused too much on analyze them in every detail, we have to be able to rely on the metalworking industry. This often results in problems this information. If these then fit the general conditions with "smeared" effects, warpage, cracking or burr forma- such as machine set-up, tools and parameters, we are able to tion. In particular, the burr formation is a concern for our achieve the desired result fairly quickly. All our trial results customers, as this makes a lot of reworking time necessary. are brought together in a knowledge database and analyzed. We often then change only a few essential small things in This database is a cornerstone of our processing knowledge the machining program to avoid rework. Many customers and supports us in the tool and process development. want a universal tool with which a majority of components and materials can be processed. Unfortunately, this is rare- ly possible, since different materials also require respective tool geometries. The tool has to be adapted especially for high-end applications, to match the material and the part. Only in this way is appropriate processing possible which is reliable and cost-effective.

16 Which plastics in your opinion are from a technical What properties do you take as a benchmark to determine machining point of view particularly critical or non-critical the machining ability of plastics? in their workability? In order to limit the machinability to some extent, we Carbon or glass-fibre filled plastics are definitely challeng- mostly need the following details: ing. Currently, more and more plastics with ceramic fillers ˌˌMaterial identification which is as accurate as possible are being used. This can make life difficult for a tool! But if ˌˌ Is the material filled or further modified? we know what is contained in the material, we can respond ˌˌDoes the material come from a rod or a sheet? accordingly. Materials such as PE, POM, PC, and PTFE can ˌˌWhat is the final product to look like? be handled without any major problems arising with the ˌˌWhat machine is available? right tools, the right parameters and a good machine. But ˌˌHow is the work-piece clamped? the framework of conditions must also agree in detail. Based on these statements, the machining ability can pos- Do you have a specific recommendation how to determine sibly be determined. We shall be pleased to also carry out the optimum machining method for plastics? tests on our own machinery. In this respect, a test protocol I need to know definitely how the machine works. How it is prepared with parameters, photos and a demonstration copes with small radii or rapid feed rates? If this has all been video. determined, I can refer to the drawings, go to the available speeds, feed rates and work-piece clamping on the selected What parameters can be used to optimise the machining tool. As soon as the tools are defined, the programs can be processes? adapted. Basic values can be found on our homepage As already mentioned, the following parameters are impor- www.hufschmied.. The counter rotation is always a big tant for good machining: issue in this respect. Many people program the machine – ˌˌTurning speed as used in the processing of steel – in counter rotation and ˌˌFeed per tooth then have major problems with burrs and a poor surface ˌˌThe clamping of the work-piece and tool finish. ˌˌSynchronised and counter rotation ˌˌCooling Are there industries where the special needs in plastics ˌˌProgram structure processing have to be particularly taken into account? The most important parameter is nevertheless the ma- Every industry has its own terms of reference to which we chining tool. have to adapt ourselves. For example, the medical device in- dustry. Dry machining is mostly carried out here. Very small Temperature parts also often have to be produced. These usually require special tools. We often work with micro-drills and extreme Softening temperature lengths in cutting. On smooth surfaces a minimum depth of roughness has to be produced. A small advantage is that Machining highly accurately working machines are used. temperature

Rotation speed

Machining t Problem area High feed rate possible but • Feathering at high rotations with limited • Cutter • Economic feed rates breakage

Ralph Hufschmied, Nabil Khairallah (Hufschmied Zerspanungssysteme), interview by Holger Werz (Ensinger GmbH)

17 Cooling and cooling lubricants

Currently there is a trend towards using dry machining with p Advantages of dry machining engineering plastics. As there is now sufficient experience ˌˌNo media residues on the components available in this area, it is frequently possible to do without hhAdvantageous for components used in medical the use of cooling lubricants. Exceptions for thermoplastic device technology or in the food industry machining processes are: (no migration) ˌˌDeep drill holes hhInfluence of cooling lubricants on the material can be ˌˌThread cutting excluded. (Swelling, change of dimensions, tension ˌˌSawing reinforced materials tearing, … ) hhNo interaction with the material However, it is possible to use a cooled cutting surface to hhFalse assessment / treatment from machinist is improve both the surface quality and tolerances of the excluded machined plastic parts, and also to allow faster feed rates s Note and consequently reduced running times. ˌˌespecially with dry machining, cooling is essential to achieve good dissipation of heat! Machining with coolants If cooling is required, it is recommended to cool ˌˌVia the chippings ˌˌUsing compressed air hhAdvantage: Cooling and removal of the chips at the Key facts at a glance same time from the working area ˌˌUse of water soluble coolants Generally speaking, dry processing is to be recommended ˌˌCommercially available drilling emulsions and cutting with heat dissipation via the machining chips. oils can also be used hh Spray mist and compressed air are very effective methods

Machining amorphous plastics ˌˌAvoid using coolants: hh Materials liable to develop tension tearing ˌˌIf cooling is imperative: hh Parts should be rinsed in pure water or isopropanol right after machining hhUse suitable coolants ˌˌPure water ˌˌCompressed air ˌˌSpecial lubricants: Information about suitable lubricants is available from your lubricant supplier

18 Annealing

Annealing process Intermediate annealing The annealing process involves thermal treatment of semi- It may also be wise to subject critical components to an finished goods, moulded or finished parts. The products intermediate annealing step when processing. This applies are slowly and evenly warmed to a material specific, defined especially, temperature level. There then follows a holding period ˌˌIf narrow tolerances are required which depends on the material and its thickness, in order ˌˌIf components with a strong tendency to warp due to to thoroughly heat through the moulded part. Subsequently the required shape need to be produced (asymmetric, the material has to be slowly and evenly cooled back down narrowed cross-sections, pockets and grooves) to room temperature. ˌˌIn the case of fibre-reinforced/filled materials (fibre orientation can enhance warping) Reducing tension by annealing hhProcessing can lead to further, enhanced tension ˌˌResidual tensions, which have arisen during being introduced into the component. manufacture or processing, can be extensively and ˌˌUse of blunt or unsuitable tools: almost completely reduced by annealing hhInitiators of tension ˌˌIncrease in the crystallinity of materials ˌˌExcessive heat input into the component – produced by hhOptimize mechanical material values inappropriate speeds and feed rates ˌˌFormation of an even crystalline structure in materials ˌˌHigh stock removal volumes - primarily as a result of ˌˌPartly improve the chemical resistance one-sided machining ˌˌReduction of warping tendency and dimensional changes (during or after processing) ˌˌSustainable improvement in dimensional stability

Semi-finished goods at Ensinger are subjected to an anneal- ing step after production. In this way, it can be ensured that the material that you receive will remain dimensionally sta- ble during and following processing and can also be better processed by machining.

Polymer Material Abbreviation Heating-up phase Maintaining phase* Cooling down phase TECASINT PI 2 h to 160 °C 6 h to 280 °C 2 h at 160 °C / 10 h at 280 °C at 20 °C / h to 40 °C TECAPEEK PEEK 3 h to 120 °C 4 h to 220 °C 1,5 h per cm wall thickness at 20 °C / h to 40 °C TECATRON PPS 3 h to 120 °C 4 h to 220 °C 1,5 h per cm wall thickness at 20 °C / h to 40 °C TECASON E PES 3 h to 100 °C 4 h to 200 °C 1 h per cm wall thickness at 20 °C / h to 40 °C TECASON P PPSU 3 h to 100 °C 4 h to 200 °C 1 h per cm wall thickness at 20 °C / h to 40 °C TECASON S PSU 3 h to 100 °C 3 h to 165 °C 1 h per cm wall thickness at 20 °C / h to 40 °C TECAFLON PVDF PVDF 3 h to 90 °C 3 h to 150 °C 1 h per cm wall thickness at 20 °C / h to 40 °C TECANAT PC 3 h to 80 °C 3 h to 130 °C 1 h per cm wall thickness at 20 °C / h to 40 °C TECAPET PET 3 h to 100 °C 4 h to 180 °C 1 h per cm wall thickness at 20 °C / h to 40 °C TECADUR PBT GF30 PBT 3 h to 100 °C 4 h to 180 °C 1 h per cm wall thickness at 20 °C / h to 40 °C TECAMID 6 PA6 3 h to 90 °C 3 h to 160 °C 1 h per cm wall thickness at 20 °C / h to 40 °C TECAMID 66 PA66 3 h to 100 °C 4 h to 180 °C 1 h per cm wall thickness at 20 °C / h to 40 °C TECAFORM AH POM-C 3 h to 90 °C 3 h to 155 °C 1 h per cm wall thickness at 20 °C / h to 40 °C TECAFORM AD POM-H 3 h to 90 °C 3 h to 160 °C 1 h per cm wall thickness at 20 °C / h to 40 °C

* At maximum temperature, unless otherwise specified.

19 An intermediate annealing step can help to reduce these Morphological changes and post-shrinkage tensions and alleviate the risk of warping. In this respect, The heat treatment of plastics always has direct effects on care should be taken that the required dimensions and the materials and their processing: tolerances are observed: ˌˌAnnealing ˌˌComponents prior to intermediate annealing should ˌˌMachining (frictional heat) first be dimensionally pre-worked with an approximate ˌˌUse (service temperature, hot steam sterilisation) safety margin (roughening) hh Annealing can lead to a certain shrinkage of the Partially crystalline plastics components ˌˌAnnealing process leads to equalisation of material ˌˌSubsequently, the final dimensioning of the parts properties should be made hh Increase in the crystallinity ˌˌSupport the component well during the intermediate hhOptimisation of mechanical properties annealing step: hhImproved dimensional stability hhAvoidance of warping during annealing hhBetter chemical resistance ˌˌMachining can lead to local overheating through frictional heat. Consequence: Representative annealing cycle hhMicrostructural changes Temperature [°C] hhPost-shrinkage ˌˌParticularly critical in this respect is TECAFORM hhImproper machining can lead to severe deformation and/or warping of the component

Amorphous plastics ˌˌAre less critical with regard to their post-shrinkage and

Time warping [h]

t1 t2 t3 t4 Warming Holding Cooling down Additional period time phase time Exemplary warpage issue due to one-sided machining

Oven temperature 1. Yellow = material to remove Temperature in centre of semi-finished part / finished part

2. Warpage after material has been removed one-sided

Key facts at a glance

Anealing/tempering leads to an optimum dimensional stability and lowers the tension level. In the case of amorphous materials, heat treatment also reduces the sensitivity to tension tearing.

20 Dimensional stability hh Partly crystalline thermoplastics exhibit high post- Dimensional stability is to be considered a characteristic in shrinkage (up to ~1.0 – 2.5 %) and are critical with every system in each process step – from the manufacture regard to warping of semi-finished plastics to the final end use. There are vari- hh Amorphous thermoplastics show only slight post- ous causes which can influence the dimensional stability of shrinkage characteristics (~0.3 – 0.7 %) and are more a component. dimensionally stable than partly crystalline thermo­ plastics Moisture uptake: ˌˌIn many cases, higher thermal expansion (compared to ˌˌPlastics with lower moisture uptake are generally very metal) must be taken into consideration much more dimensionally stable. Example: TECAFORM AH / AD, TECAPET, TECATRON, u Processing TECAPEEK ˌˌEnsure good heat dissipation in order to avoid local hh Can be achieved with narrow tolerances temperature rise ˌˌPlastics with high levels of moisture uptake show a ˌˌIn the case of higher machining volumes it may be marked influence on dimensional stability advisable to introduce an intermediate annealing step, Example: TECAMID, TECAST in order to reduce the development of tension hh Moisture uptake/release leads to swelling or ˌˌPlastics require greater production tolerances than metals shrinkage of the material ˌˌAvoid higher tensional forces, in order to avoid distortion hh Conditioning is possibly recommended prior to ˌˌIn the case of fibre-reinforced materials in particular, processing attention should be paid to the position of the component in the semi-finished goods (observe Tension relaxation extrusion direction) ˌˌInternal or “frozen in” tension acts only partly or has ˌˌWhen machining, a component optimised procedure little effect on the dimensional stability of the finished should be chosen part during processing at room temperature. hhDimensionally stable finished part ˌˌDuring storage or in use, this “frozen in” tension can break down hhDimensional changes. ˌˌParticularly critical: Use of components at higher temperatures: hhTension can be reduced suddenly. hhChange of shape, warping or in the worst case tension tearing when using the component

Heat input ˌˌAll processes are critical in which heat develops in the material hh Example: Annealing, machining, use at high temperatures, sterilisation ˌˌTemperatures above the glass transition temperature have an effect on microstructural changes and thus post-shrinkage after renewed cooling down hhShrinkage and warping are particularly apparent in asymmetrical component geometries

21 Product groups and material characteristics

In the most unfavourable case, the centre is of a brittle and TECAFORM AH / AD, hard character. Added to the internal tension produced by TECAPET, TECAPEEK extrusion technology, machining can carry a certain risk of producing tension cracking. Semi-crystalline, unreinforced materials TECAFORM AH / AD, TECAPET and TECAPEEK are very In addition, it should be remembered that as a consequence dimensionally stable materials with balanced mechanical moisture uptake can change the dimensions of the material. properties. These materials are very easy to machine and This “swelling” has to be allowed for in the processing and basically tend to produce short chips. They can be machined design of components made of polyamide. The moisture with very high delivery and high feed rates. uptake (conditioning) of semi-finished goods plays an im- portant part in the case of machining. Especially thin- Fundamentally, however, it is important to pay attention walled components (up to ~10 mm) can absorb up to 3 % during processing to a low heat input as far as possible, as moisture. As a rule of thumb: TECAFORM as well as TECAPET in particular have a high ˌˌA moisture uptake of 3 % causes a dimensional change tendency to undergo post-shrinkage by up to ~2.5 % - of about 0.5 % ! warping can arise thereby due to local overheating. Machining of TECAST T In the case of the materials mentioned above, very low sur- ˌˌTends to produce short chips face roughness can be achieved with optimised machining ˌˌIs therefore good to machine parameters. Machining of TECAMID 6 and TECAMID 66 ˌˌForm a flow of chips ˌˌMore frequent removal of chips from the tool/work- TECAST T, TECAMID 6, piece can be necessary TECAMID 66 () ˌˌImportant in order to generate chips which break off when they are very short and to avoid breakdowns in Unreinforced Polyamides the process: It should generally be remembered with polyamides: hhIdeal machining parameters TECAST T, TECAMID 6 and TECAMID 66 are materials hhChoice of suitable tools based on polyamides. Contrary to the previously mentioned­ materials, it should be remembered that polyamides have Generally speaking, we recommend pre-heating to 80 – naturally very brittle characteristics – this may also be re­ 120 °C with larger dimensioned work-pieces (e.g. round ferred to in the context of a “freshly moulded” condition. rods > 100 mm and sheets with a wall thickness > 80 mm) Due to their chemical structure, the polyamides tend, how- and machining close to the centre, in order to avoid tension ever, to absorb moisture - this property gives the polyamides cracking during processing. their very good balance between toughness and strength.

The moisture uptake via the surface leads to a virtually constant distribution of water content over the entire cross section with small semi-finished dimensions and compo- nents. In the case of larger dimensioned semi-finished Key facts at a glance goods (in particular for round rods / sheets of 100 mm diameter / wall thickness upwards) the moisture content Amorphous plastics should be dry machined as far as decreases from the outside inwards. possible. If the use of a cooling lubricant is absolutely necessary, the component should be subsequently cleaned immediately afterwards.

22 TECANAT, TECASON, ˌˌAvoid re-cutting with the milling machine hhAlso leads to rougher surfaces TECAPEI ˌˌA further “re-cutting process” may be necessary in order to smooth spikes to the desired surface quality Amorphous thermoplastics ˌˌDe-burring is often also necessary TECANAT, TECASON, TECAPEI are amorphous materials, Select a suitable tension, in order to avoid the component which are very prone to develop tension cracking in contact “dying away” and as a result components that are not true with aggressive media, such as oils and fats. Also, cooling to size. lubricants often contain media, which can trigger tension in the material. For this reason, avoid using cooling lu- bricants when machining these materials as far as possible or, for example, a water-based medium should be used. TECASINT Similarly, material specific machining parameters should Polyimide products produced by a sintering process be selected as far as possible. The TECASINT product groups 1000, 2000, 3000, 4000 and ˌˌDo not use feed rates which are too high 5000 can be processed dry or wet on standard metal work- ˌˌAvoid the use of higher pressures ing machinery. ˌˌAvoid excessively high tensions ˌˌPreferably select a higher rotational speed s Recommendations ˌˌUse suitably sharp tools Tools ˌˌUse fully hardened metal tools s To be observed with construction designs ˌˌTools with a cutting angle as used for aluminium Construction designs should be adapted to match amor- processing are very suitable phous materials. ˌˌFor highly filled TECASINT products with e.g. glass ˌˌAvoid shearing forces (constructive and in processing) fibres, glass beads, use tools fitted with diamond or ˌˌDesign edges/geometries according to the type of ceramic tips material (preferably choose inner edges which are slightly rounded-off) Processing ˌˌHigh cutting speeds and low feed rates coupled with The materials can be used to manufacture very dimen­ dry machining improve the result sionally stable prefabricated parts with very narrow toler- ˌˌWet processing increases the cutting pressure and ances, taking suitable machining parameters into account. promotes the formation of flash, but is recommended to extend the tool life ˌˌSynchronous milling to prevent chipping and cavities TECA materials with PTFE ˌˌIntermediate tempering is normally not necessary Materials containing a PTFE component (e.g. TECAFLON s Due to the increased tendency of polyimides to absorb mois- PTFE, TECAPEEK TF, TECAPEEK PVX, TECATRON PVX, ture, it is advisable to seal these parts in a vacuum barrier film. TECAPET TF, TECAFORM AD AF) frequently exhibit In order to avoid dimensional changes to very high quality parts slightly lower mechanical strength. Due to this PTFE content, due to moisture absorption, these are opened just before use. several aspects should be remembered when processing. s Pay attention to the following when machining these materials: ˌˌMaterials tend to lag behind the milling tool hhThere is a distinct increase in surface roughness (hair formation, spikes, rough surface)

23 ˌˌFinal manufacture after cooling down to room Fibre reinforced temperature TECA materials ˌˌTooling should also be heated before processing hhAvoid heat dissipation from the material Fibre reinforced materials include all types of fibres. We are concentrating on the most important products in Processing these machining recommendations, including carbon-fibre ˌˌEven fly-cutting of the bilateral edge zones of the reinforced products (amongst others, TECAPEEK GF30, semi-finished part: TECAPEEK CF30, TECAPEEK PVX, TECATRON GF40, hh Ideally, each fly-cutting process should have a max. TECTRON PVX, TECAMID 66 GF30, TECAMID 66 CF20) cutting depth of 0.5 mm and glass-fibre reinforced products. hhResults in more homogenous distribution of tension in the semi-finished part u Recommendations hhLeads to a higher quality of the component Tooling ˌˌUse hardened steel tools (carbide steel K20) in any case, Example or ideally polycrystalline diamond tooling (PCD) We recommend, for example, with final dimensions of ˌˌUse very well sharpened tools 25 mm to use a 30 mm thick sheet, which is to be fly cut ˌˌRegular control checks of tools, due to the abrasive 2 mm on both sides prior to machining. In this case, the effects of the materials sheet should be turned over several times and max. 0.5 mm hhHigher standing times removed per working step. Ideally, this preliminary work hhAvoid too much temperature input should be carried out on a pre-warmed semi-finished part. Subsequently, the final processing is carried out on the Clamping semi-finished goods cooled, pre-processed product. This process ensures in any ˌˌClamp in the extrusion direction (highest compression case an optimal component quality with low tension and strength) minimum warping of the component. ˌˌUse the lowest possible tensions hhAvoid sagging and flexural strain hhReduced warping and/or the danger of tension Key facts at a glance cracking in the component For better tooling stand times and dimensional stability, Pre-heating the use of carbide steel or PCD tools is recommended ˌˌPre-heating of semi-finished goods may be with fibre reinforced materials. recommended for their further processing hhGreater material durability ˌˌSemi-finished goods should be moderately heated for this purpose ˌˌWe recommend a heating rate of 20 °C per hour to 80 – 120 °C. ˌˌFor even temperature distribution in the semi-finished goods cross-section, we also recommend a holding time of at least 1 hour per 10 mm wall thickness. ˌˌAt this temperature, the semi-finished parts should be prefabricated with oversize

24 Besides higher standing times, these tools help to minimise Special case TECATEC the feed forces, when the specific material is also consid- ered in the design. Composite ˌˌSelect a moderate cutting sharpness TECATEC is a composite based on a polyarylether ketone ˌˌEstablish a good balance between surface quality (with with 50 and / or 60 % by weight carbon fibre fabric. The very sharp blades) and tooling standing times (blunter machining of TECATEC is considerably more complex cutting blades) than the machining of short fibre-reinforced products. Due ˌˌDesign milling geometries so that the fibres are cut. to the layer structure of the material, incorrect machining Otherwise there is a danger of fibre fringing can lead to different effects: ˌˌDue to the higher abrasiveness of the carbon fibres, ˌˌEdge chipping regular changing of the TECATEC tools is necessary ˌˌDe-lamination hh Avoid too much heat input and warping due to ˌˌFringing blunt tools ˌˌBreaking through of fibres For this reason, specific processing is required for this Machining material. This has to be established case for case, according ˌˌThere is a greater risk of chipping and burr formation to the component in question. during the machining process with the fibres running parallel to the than when processing is Design of semi-finished goods vertically to the woven fabric The suitability of TECATEC for a certain use and the quality ˌˌFor narrower tolerances, the components can also be of the finished part primarily depends upon the position of tempered several times during manufacture the component in the semi-finished part. In the develop- ˌˌDue to relatively good heat dissipation thanks to the ment phase, the directionality of the fibre fabric must already higher fibre content, good heat distribution in the work be urgently considered, especially with regard to the type of piece can be expected. For this reason, we recommend load (pulling, compression, bending) on the application that the material be dry machined. and the later machine processing. Machining and tooling parameters Machining tools and tooling materials We recommend that attention is paid to the following For higher standing times in comparison to HSS or carbide parameters: steel tools, we recommend the use of ˌˌAvoid using high feed forces ˌˌPCD tools (polycrystalline diamond) ˌˌVery high point angles (150 – 180°) ˌˌCeramic tools ˌˌVery low feed rates (approx. < 0,05 mm/min) ˌˌTitanium coated tools ˌˌHigh cutting rates (approx. 300 – 400 m/min) ˌˌTools with functional coatings (plasma technology) This information is intended to provide initial assistance in the machining of TECATEC - detailed information depends on the individual case.

25 Machining errors – causes and solutions

Cutting and sawing Turning and milling

Difficulties Root causes Difficulties Root causes

Surface has ˌˌBlunt tool Surface has ˌˌBlunt tool or shoulder friction started to melt ˌˌInsufficient lateral play / clearance started to melt ˌˌInsufficient lateral play / clearance ˌˌInsufficient coolant feed ˌˌFeed rate too low ˌˌSpindle speed too high Rough surface ˌˌFeed rate too high ˌˌTool unprofessionally sharpened Rough surface ˌˌFeed rate too high ˌˌCutting edge not honed ˌˌIncorrect clearance ˌˌSharp point at the tool Spiral marks ˌˌTool friction during withdrawal (slight radius on point of ˌˌBurr on the tool milling cutter required) Concave and ˌˌPoint angle too great ˌˌTool not centrally mounted convex surfaces ˌˌTool not vertical relative to Burr on corners of ˌˌNo space in front of the cutting the spindle cutting edge diameter ˌˌTool is deflected ˌˌBlunt tool ˌˌFeed rate too high ˌˌInsufficient lateral play / clearance ˌˌToo mounted above or below ˌˌNo lead angle at the tool the centre Cracks or flaking ˌˌToo much positive inclination "Stumps" or burr ˌˌPoint angle not large enough at the corners at the tool at the end of the ˌˌBlunt tool ˌˌTools not sufficiently run-in cutting surface ˌˌFeed rate too high (action of tool is too hard on Burr on the ˌˌBlunt tool the material) outside diameter ˌˌNo space in front of the cutting ˌˌBlunt tool diameter ˌˌTool mounted under the centre ˌˌSharp point at the tool (slight radius on point of milling cutter required)

Chatter marks ˌˌExcessive radius on point of milling cutter at the tool ˌˌTool not sufficiently firmly mounted ˌˌInsufficient material guidance ˌˌCutting edge width too great (use 2 cuts)

26 Drilling

Difficulties Root causes Difficulties Root causes

Tapered drill holes ˌˌIncorrectly sharpened drill bits Nonconcentric ˌˌExcessively high feed rate ˌˌInsufficient play / clearance drill holes ˌˌSpindle speed too low ˌˌExcessively high feed rate ˌˌDrill penetrates too far into next part Burnt or melted ˌˌUse of unsuitable drill bits ˌˌParting-off tool leaves "stump" surface ˌˌIncorrectly sharpened drill bits which deflects the drill bit ˌˌInsufficient feed rate ˌˌLand too thick ˌˌBlunt drill bit ˌˌDrilling speed too high at the start ˌˌLand too thick ˌˌDrill not clamped centrally Surface splitting ˌˌExcessive feed rate ˌˌDrill not correctly sharpened ˌˌExcessive play / clearance Burr left after ˌˌBlunt cutting tools ˌˌExcessive incline (thin land as parting off ˌˌDrill does not travel completely described) through the part Chatter marks ˌˌExcessive play / clearance Drill quickly ˌˌFeed rate too low ˌˌInsufficient feed rate becomes blunt ˌˌSpindle speed too low ˌˌDrill overhang too great ˌˌInsufficient lubrication due to ˌˌExcessive incline (thin land as cooling described)

Feed marks or ˌˌExcessively high feed rate spiral lines at the ˌˌDrill not centred inside diameter ˌˌDrill tip not in centre

Overdimensioned ˌˌDrill tip not in centre drill holes ˌˌLand too thick ˌˌInsufficient play / clearance ˌˌExcessively high feed rate ˌˌDrill point angle too great

Underdimensioned ˌˌBlunt drill bit drill holes ˌˌExcessive play / clearance ˌˌDrill point angle too small

Key facts at a glance

Please do not hesitate to contact our technical application advise service for technical information: [email protected] or by telephone on Tel. +49 7032 819 101

27 supplant classicallyusedmaterials. Their economy and performance benefitshaveseenthem frequently today. sector important ofindustry Ensinger are usedinalmostevery Thermoplastic engineeringandhigh-performance plasticsfrom www.thermix.de +49Fax 751 35452 22 Tel. +49 751 35452 0 88214 Ravensbur Mooswiesen 13 Ensin er GmbH www.ensin er-online.com +49Fax 29479722 77 Tel. +49 29479722 0 59609 Anröchte Borsi straße 7 Ensin er GmbH www.ensin er-online.com +49Fax 396 9971 570 Tel. +49 396 9971 0 93413 Cham Wilfried-Ensin er-Straße 1 Ensin er GmbH www.ensin er-online.com +49Fax 7457 9467122 Tel. +49 7457 9467100 72108 Rottenbur a.N. Mercedesstraße 21 Ensin er GmbH www.ensin er-online.com +49Fax 7032 819 100 Tel. +49 7032 819 0 Nufrin en 71154 Rudolf-Diesel-Straße 8 Ensin er GmbH Ensinger Germany www.ensin er.dk +45Fax 7810 4420 Tel. +45 7810 4410 4100 Rin sted Ru væn et 6B Ensin er DanmarkA/S Denmark www.ensin er.cz +42037Fax 7972059 Tel. +42037 7972056 33441 Dobřany P.O. Box15 Prùmyslová 991 Ensin er s.r.o. Czech Republic www.ensin er-china.com +862152285222 Fax Tel. +862152285111 P.R.China Shan hai 200233 No. 1528GumeiRoad 1F, Buildin A3 Ensin er (China) Co., Ltd. China www.ensin er.com.br +5551Fax 35882804 Tel. +5551 35798800 93.032-000 SãoLeopoldo-RS Av. SãoBorja3185 Plásticos Técnicos Ltda. Ensin er Indústriade Brazil www.ensin er-sintimid.at +437672Fax 96865 Tel. +437672 7012800 4860 Lenzin Werkstraße 3 Ensin er SintimidGmbH Austria Ensinger worldwide www.ensin er.pl +4865 5295811Fax Tel. +4865 5295810 64-100 Leszno ul. Geodetów 2 Ensin er Polska Sp.zo.o. Poland www.ensin er.jp +81Fax 35878 1904 Tel. +81 35878 1903 134-0086, Japan TokyoEdo awa-ku, 3-5-1, Rinkaicho, Ensin er JapanCo., Ltd. Japan www.ensin er.it +390331Fax 567822 Tel. +390331 568348 Garolfo 20020 Olcella diBusto Via Franco Tosi 1/3 Ensin er ItaliaS.r.l. Italy www.ensin er.in +91202674Fax 1001 Tel. +91202674 1033 411 014Pune Viman Na ar Plot No. 17, Loh aon, No. Plaza, Survey R.K 206/3 Plastics Private Ltd. Ensin er IndiaEn ineerin India www.ensin er.fr +33478556841Fax Tel. +33478554574 Beynost 01700 ZI Nord ZAC lesBatterses Ensin er France S.A.R.L. France www.ensinger-online.com www.ensin er-inc.com +1724Fax 746 9209 Tel. +1724 746 6050 Washin ton, PA 15301 365 Meadowlands Boulevard Ensin er Inc. USA www.ensin er.co.uk +441443675777 Fax Tel. +441443678400 Mid Glamor anCF398JQ Tonyrefail Wilfried Way Ensin er Limited Kingdom United www.ensin er.se 440418 +46171 Fax Tel. 050 477 +46171 SE-749 40Enköpin 5Stenvrets atan Ensin er SwedenAB Sweden www.ensin er.es +3493Fax 5742730 Tel. +3493 5745726 Barcelona 08120 La Lla osta Girona, 21-27 Ensin er S.A. Spain www.ensin er.com.s +65 65525177 Fax Tel. +65 65524177 669569Sin apore Lam SoonIndustrialBuildin 63 HillviewAvenue #04-07 (Sin apore Branch) Ensin er InternationalGmbH Singapore

11/13 E9911075A004GB