Int. J. Mech. Eng. & Rob. Res. 2014 Manu Srivastava et al., 2014 ISSN 2278 – 0149 www.ijmerr.com Vol. 3, No. 3, July, 2014 © 2014 IJMERR. All Rights Reserved Review Article TRENDS IN THE DOMAIN OF RAPID ROTOTYPING: A REVIEW Manu Srivastava*1, Utkarsh Singh1 and Ramkrishna Yashaswi2 *Corresponding Author: Manu Srivastava [email protected] RP answers the need of green manufacturing which is the need of hour in the manufacturing sector. A large number of commercially viable RP techniques are available in the market today. This paper attempts to introduce and review the newer RP technologies. It summarizes the applications of different commercial RP technologies available. It finally recognizes the current challenges in this field and suggests probable solutions based on extensive literature survey. Keywords: RP, SLS, SLA, 3DP, SDM, LENS, FDM, RP classification, RP applications INTRODUCTION green manufacturing which are different In product design, prototyping is an impera- names for this automatic prototyping tive final step. Prototyping requires design, (Debasish Dutta et al., 2001). Advent of RP fabrication and testing of final product design. is a watershed event similar to advent of CNC This practice started with manual prototyping tools almost 3 decades ago (John Michael then extended to prototyping with soft curves and presently prototyping is done with the Brock et al., 2012).This marks an era of aid of computers and is called rapid introduction of flexible automation. This prototyping. RP/LM is accomplished by layer- process tremendously reduces the design on-layer material deposition. This started cycle time especially for intricate and during early 1980s with massive complicated jobs. improvement in CAD/CAM technologies. Despite this tremendous growth in this The current trend is the direct manufacturing of physical objects starting field, there are numerous challenges to be from 3D CAD models without any classical dealt in this field. While outlining the problems tools. This is termed rapid prototyping, solid in RP applications; this paper also highlights freeform fabrication, layered manufacturing, the applications. 1 Netaji Subhas Institute of Technology, New Delhi. 2 Institute of Management Technology, Ghaziabad. 747 Int. J. Mech. Eng. & Rob. Res. 2014 Manu Srivastava et al., 2014 WORKING STEPS REQUIREMENTS 4. Merging 1. Geometric modeling 5. Building the model 2. Data transfer and CAD interface 6. Starting the machine 3. Slicing 7. Final post curing and finishing works CONVENTIONAL CLASSIFICATION Figure 1: Conventional Classification of RP Processes Layered Manufacturing Processes (On basis of raw material state in compliance with Kruth Classification) Gaseous Solid Liquid Paste Foil Chemical Wire Reaction LCVD Paste Lamp Solid Multi Polymerizatio Ground Componen n Process Curing Layered Heat Fused Layer t Powder Laminate Thermal Modelling & d Polymerizati Ballistic Part Solid Foil Light of on Manufacturing Polymerizati One on frequency 3D Printing Selective (Topograph Laser y Sintering Holographic interference Laser Beam solidification Stereo lithography An alternative approach to classification is suggested by D.T. Pham, R.S. Gault Figure 2: Alternative Classification of RP Processes Rapid Prototyping Addition of Removal of Material Material Liquid Discrete Particles Fusing of Solid particles using Sheet Laser Solidification of Molten Material Bonding of Solidification of sheets using Solidification a Liquid light of Electro set Polymer Bonding of Fluid sheets using Layer Joining of Point adhesives by Particles Layer by using Binder Point Holographic Surface Point by Layer by Point Layer 748 Int. J. Mech. Eng. & Rob. Res. 2014 Manu Srivastava et al., 2014 RAPID PROTOTYPING conventional machining processes (H S Cho TECHNIQUES et al., 2000). SLA fabricates parts without Stereo Lithography intermediate tooling, directly from a CAD It is a rapid prototyping technique that model, in the opposite direction to gravity. involves photo polymerization that draws or Support structure is required to hold the prints on a photo curable resin, the cross stacked layer and resin during the fabrication section of a model. This is a recent technique process. The stair -stepping effect occurs by that attracted much attention because of its staking layers when fabrication on an inclined ability to make wide range of products with surface (Ho-Chan Kima and Seok-Hee Lee, high accuracy. However, the dimensional 2005). accuracy produced is not better than Figure 3: Stereo Lithography Apparatus X-Y scanning mirror Laser source Layered part Laser beam Elevator for Building platform vertical motion set to move in vertical direction Sweeper for leveling the current layer Liquid polymer Selective Laser Sintering process is repeated so that entire stack of 2- A freeform, additive manufacturing process D layers is created and bonding takes place that uses laser on power beds to create 3-D to form the original 3-D CAD solid model (E models. Its starting point is a 3-D CAD model O Olakanmi, 2013). of part geometry out of which 2-D stack of layers are derived which represent the part. Electron Beam Melting A laser spot is created by scanning over the It is an additive manufacturing process, which cross sectional area to create each layer, forms a 3D object based on a computer which results in sintering, melting and model by utilizing an electron beam to melt bonding particles in a lamina. The same alloyed metal powder layer by layer. This 749 Int. J. Mech. Eng. & Rob. Res. 2014 Manu Srivastava et al., 2014 technique unlike conventional techniques, with various material, including Co-Cr-Mo anticipates microstructure and properties of Alloy (R S Kircher et al., 2009).The parts are EBM produced material. It is emerging as a build up in a vacuum chamber. Later the parts method for production of orthopedic devices are cleaned by conventional techniques Figure 4: SLS Machine Setup X-Y scanning mirror Laser Laser beam Sintered part Levelling roller Powder bed Powder feed supply Platform and piston arrangement for vertical motion Electron Beam Melting EBM produced material. It is emerging as a It is an additive manufacturing process, which method for production of orthopedic devices forms a 3D object based on a computer with various material, including Co-Cr-Mo model by utilizing an electron beam to melt Alloy [32].The parts are build up in a vacuum alloyed metal powder layer by layer. This chamber. Later the parts are cleaned by con- technique unlike conventional techniques, ventional techniques anticipates microstructure and properties of Figure 5: Electron Beam Melting Setup Hopper Electron Material released from beam hopper Support material Work piece layer formation Piston arrangement for vertical motion 750 Int. J. Mech. Eng. & Rob. Res. 2014 Manu Srivastava et al., 2014 Solid Ground Curing application of the prototypes. However the It is a process is suitable for building parts in method offers very high fabrication rate with batch, with different dimensions and adequate accuracy, complexities lie high geometry. Although problems like quality, accusation rate and operating cost are the material properties and accuracy limit the biggest hurdles. Figure 6: Solid Ground Curing Process UV lamp with shutter UV rays Masked plate Liquid Polymer Wax Base Laser Stereo Lithography obtained from the CAD model but not in terms A wide variety of material can be processed of slices. It also has still not been commer- by high power laser. It uses ultraviolet laser cialized. as a source when applied to organic Laser Engineered Net Shaping compounds in a conventional process. In the It is a freeform fabrication process. It involves traditional approach the process of fabrication fully dense 3D shapes from laser processing and development of models allow curing of of ?ne powders, directly from a design model. part by exposing to UV light, leading to The LENS process makes near net shaped formation of 3D object. complex prototypes, leading to reduction in machining and time cost. The LENS process Holographic Interference can be used to deposit a variety of metals Solidification and alloys, such as 316 stainless steel, The entire surface is solidified by exposing titanium alloys and H13 steel nickel-base the resin to holographic image. The image is super alloys (J N DuPont, 2003). 751 Int. J. Mech. Eng. & Rob. Res. 2014 Manu Srivastava et al., 2014 Figure 7: Lens Setup Laser beam Focused lens Concentrated laser Powder delivery nozzle Work piece Melt pool Base Figure 8: Shape Deposition Modelling Shaping of the Support support deposition Embedding another component Part deposition Shaping the part 752 Int. J. Mech. Eng. & Rob. Res. 2014 Manu Srivastava et al., 2014 Shape Deposition Modelling Since the product is monolithic so no It creates metal parts with incremental boundary layers are there I end product, this deposition of metal and removal of material is in spite of the fact that the mold is built in as well. It adds the benefits of SFF and CNC. layers (A G Cooper et al., 1999). It produces parts with poor surface quality. The non-horizontal and vertical surfaces Three Dimensional Printing exhibit stair step effect. The mechanical It involves the creation of 3D object by properties are critical to layer boundaries depositing powder with the help of a liquid which are a potential source of defect. To binder. It is a very versatile process which solve these problems mold SDM was can make variety of complex models with developed which can build complex shaped different kinds of material. They have very parts. However, it uses CNC milling to shape low cost, high speed and wide application the surfaces effected by stair step effect. Figure 9: 3D Printing Machine control unit Leveling roller Inkjet print heads Support powder Part Platform along with piston for vertical movement Electro Setting Laser-Assisted Chemical Vapor Conductive Material like aluminum is used. Deposition After printing of all the layers, stacking is done Technique using gas phase conversion to and they are then immersed in electro setting solid structure with the help of pyro lytic fluid.