Application and Development of Rapid Prototyping Technology Part Four Application of Rapid Prototyping Technology

At present, rapid prototyping technology has been widely used in aerospace, industrial modeling, mechanical manufacturing (automobile, motorcycle), military, construction, film and television, household appliances, light industry, medicine and other fields.

1. Application in Aerospace Technology

   In the field of aerospace, aerodynamic ground simulation experiments (i.e. wind tunnel experiments) are indispensable to the design of advanced space-to-Earth shuttle systems (i.e. space shuttles). The model used in this experiment has complex shape, high precision and streamlined characteristics. RP technology is adopted. According to the CAD model, the entity model can be automatically completed by RP equipment, which can ensure the quality of the model.

   For aviation, aerospace, national defense, automobile and other manufacturing industries, the basic core components are mostly asymmetric, which have irregular free-form surface or complex metal parts with fine structure (such as blade, impeller, intake manifold, engine cylinder block, cylinder head, exhaust pipe, oil line, etc.). The manufacturing process of the die is very difficult, so RP technology is urgently needed to play a greater advantage in rapid tooling. Rapid prototyping technology is used to directly or indirectly manufacture lost foam, lost foam concave die, casting pattern, template, mold, core or shell for casting, and then metal parts can be quickly manufactured by combining traditional casting technology.

2. Application in the Process of New Product Modeling Design

   Rapid prototyping technology has established a brand-new product development model for industrial product designers and developers. The application of RP technology can quickly, directly and accurately transform design ideas into physical models (samples) with certain functions, which shortens the development cycle, reduces the development costs, and also makes enterprises take the lead in the fierce market competition.

3. Application in Machinery Manufacturing

   Because of the characteristics of RP technology, it has been widely used in the field of mechanical manufacturing. It is mostly used in the manufacture of single-piece and small-batch metal parts. Some special complex parts can be directly moulded by RP technology because they only need to be manufactured in a single piece or in small batches of less than 5O parts. Generally, RP technology can be used for direct moulding. The cost is low and the cycle is short.

4. Application in Die Manufacturing

   At present, there are two methods of rapid tooling: indirect tooling and metal direct tooling. Rapid die making methods which are commonly used are soft die, bridge die and hard die.

   Soft Tooling usually refers to silicone rubber die. The prototype manufactured by SLA, FDM, LOM or SLS technology is turned into a silicone rubber mold, then the two-component polyurethane is poured into the mold, and the required parts are obtained after curing.

   Bridge Tooling usually refers to the epoxy resin mould which can be directly produced by injection moulding. Compared with traditional injection moulds, the cost of using epoxy resin moulds is only a fraction of that of traditional methods, and the production cycle is greatly reduced.

   Hard Tooling usually refers to the indirect manufacturing of metal dies and the direct processing of metal dies by rapid prototyping. At present, wax or resin models are manufactured by SLA, FDM and SLS methods, metal parts are produced by investment casting, and casting cavity can be manufactured by SLS method.

   For many years, the technology of metal direct forming and rapid tooling has mainly been selectively using laser sintering (SLS) to directly manufacture metal molds.

   This kind of sintered parts usually have low density porous structure, and the metal with low melting point phase can be infiltrated into the metal mould directly.

   Using SLA, SLS, FDM or LOM to process wax patterns in investment casting is one of the most important ways to produce metal parts and dies. The surface of the prototype obtained by rapid prototyping is replaced by special exterior wood mold, and the gypsum or ceramic mold is manufactured directly, or the gypsum or ceramic mold is obtained by the transition of RP prototype through silicone rubber mold, and then the metal mold is poured out by gypsum or ceramic mold. This is also one of the effective methods.

5. Application of Laser Rapid Prototyping Technology

   Laser Rapid Prototyping (LRP) is a new manufacturing technology which integrates advanced technologies such as CAD, CAM, CNC, laser, precision servo drive and new materials. Compared with traditional manufacturing methods, it has high reproducibility and interchangeability of prototype; manufacturing process has nothing to do with the geometric shape of prototype; processing cycle is short, cost is low, general manufacturing cost is reduced by 50%, processing cycle is shortened by more than 70%; high technology integration is achieved and the integration of design and manufacturing is achieved.

   Recent developments in LPR include: stereo optical modeling (SLA), selective laser sintering (SLS), laser cladding forming (LCF), Laser Engineered Net Shaping(LENS), laser sheet lamination manufacturing (LOM), laser induced thermal stress forming (LF) and three-dimensional printing.

6. Stereo light forming (SLA) technology, also known as photo-curing rapid prototyping technology. The United States, Japan, Germany, Belgium and other countries have invested a lot of manpower and material resources in the research of this technology, and new products are constantly coming out. The stereo light moulding machine LPS600A has also been developed by Xi'an Jiaotong University. At present, more than 10 factories around the world produce this product.

7. Selective laser sintering (SLS) technology is similar to SLA technology. The SLS technology studied by Texas State University has been commercialized by DTM Company in the United States. At present, the company has developed SLS2000 series of third generation products.

8. The working principle of laser cladding forming (LCF) technology is basically the same as other rapid prototyping technologies. The difference is that laser cladding forming can produce very dense metal parts, whose strength can reach or even exceed those produced by conventional casting or forging methods, so it has good application prospects.

   (4) LENS technology combines SLS technology with LCF technology and maintains the advantages of these two technologies.

   (5)LOM technology is a new rapid prototyping technology commonly used to make dies. The cost of die producing by LOM technology is about 1/2 less than that by traditional method, and the production cycle is greatly shortened. It can be used to make composite dies, thin dies, progressive dies and so on. The economic benefit is also remarkable. Technology has been widely used abroad.

9. LF technology is based on the characteristics of metal thermal expansion and contraction, i.e. non-uniform heating of materials to produce predetermined plastic deformation. German scholars M. Geiger and F. Vollertsen have done a lot of research on laser forming and other processing methods. At present, this technology has been applied to the flexible leveling of automobile panel and the forming of other special-shaped parts.

   Other applications include: the application of laser rapid prototyping technology in the preparation of functionally gradient materials; the application of laser surface modification of metal materials and laser rapid prototyping technology for high performance metal parts. Laser surface alloying and laser cladding surface modification technology based on the synthesis and preparation of fast solidification new materials is one of the most effective ways to improve the high temperature performance of Aeronautical metal materials such as titanium alloy, and high temperature wear resistance and corrosion resistance of high temperature moving parts.

   Research on Laser Direct Rapid Prototyping Technology for metal parts abroad includes the research of Laser Engineered Net Shaping, Laser Forming, Directed Light Fabrication, Shape Deposition Manufacturing, Direct Metal Deposition, Controlled Metal Buildup, Manufacturing Process. The wide application and rapid development of laser direct rapid prototyping (LDRP) technology for metal parts in the world show its broad development prospects and represent the development direction of RP technology.

   The domestic research of laser direct rapid prototyping technology for metal parts includes the research of forming process based on LENS and DLF principle; the research of forming process based on DMD principle; the research of forming process based on SDM principle; the research of other laser direct prototyping process. Laser cladding direct rapid manufacturing technology combines selective laser sintering technology with laser cladding technology. It can rapidly prototype metal functional parts with full density and high performance. With its unique advantages, it has attracted more and more attention of researchers and industry, and has extremely broad market demand and application prospects.

   The latest development of laser rapid prototyping technology includes metal parts direct prototyping technology, micro-nano laser three-dimensional prototyping technology, laser direct writing three-dimensional stacking technology, composite materials light curing forming technology, etc.