Overview
Rapid prototyping and manufacturing (RP&M) is a new technology that can directly obtain solid models or molds from CAD models. It eliminates the need for traditional processing tools and molds, shortens product development cycles, reduces manufacturing costs, and supports fast markets. One of the necessary tools for response has been widely used in recent years. Numerous domestic and foreign companies are actively applying RP&M technology to accelerate product development and technological advancement, and have achieved success in product design and inspection, appearance review, assembly experiment, dynamic analysis, stress analysis, wind tunnel experiment and rapid mold.
Classification and application
According to whether the rapid mold is directly manufactured by the rapid prototyping machine, the rapid mold can be divided into two categories: direct manufacturing and indirect manufacturing. The application process has its own characteristics. The specific analysis is as follows:
Rapid mold manufacturing
Rapid mold direct manufacturing is a mold that is driven by a CAD model to be directly formed by layering a rapid prototyping machine. Due to the short process flow, mold forming is faster, the process is easier to control, and direct manufacturing of metal molds has become the most promising advanced technology, which is the goal pursued by rapid mold manufacturing technology.
Laser selective sintering technology
Rapid mold manufacturing The most successful rapid prototyping process is laser selective sintering (SLS). The process is as follows: a high-energy laser selectively sinters the powder into a layer, and after sintering layer by layer, the unsintered loose powder is removed, and then used as a mold after high-temperature sintering and copper infiltration. This method has been successfully applied in small injection molds and blow molds. The directme ​​tallasersintering (DMLS) process is a new direct mold manufacturing technology developed by EOS in Germany based on the SLS process. The metal powder is directly sintered without an intermediate binder, and the die density is close to that of pure metal. The DMLS mold does not need to be subjected to high-temperature sintering and copper infiltration at a later stage, but a high-temperature epoxy resin needs to be infiltrated into the surface. At present, the precision of the mold can reach 0.05 mm, and the injection mold can inject up to 15,000 pieces of plastic parts. Several hundred metal parts can be cast in the die casting mold.
Laser powder cladding near net forming technology
Laser powdered netshaping (LENS) is a rapid metal part and mold manufacturing process based on laser cladding technology. The formed parts are densely organized, have obvious rapid melting characteristics, high mechanical properties, and can achieve non- Manufacture of homogeneous and gradient material parts and molds. However, due to the influence of thermal stress and the lack of supporting materials, the manufactured molds can not meet the requirements of most molds in terms of surface roughness value and dimensional accuracy, which limits the application of LENS process in the field of mold manufacturing.
Thin layer object stacking technique
The laminated object manufacturing (LOM) process uses a heating roll and a laser beam to bond and cut the hot-melt-coated sheet material (paper, plastic, metal, etc.) layer by layer to form the cross-section of the mold. The contour is finally made into a mold. Since the bonding temperature and the ambient temperature of the metal sheet are difficult to coordinate and control, the metal sheet is easily twisted by heating, bonding, and cooling, and the mold forming quality is not very high.
3D printing technology
The 3D printing (3DP) process uses a binder nozzle to selectively spray a binder to bond metal powders such as stainless steel, tungsten carbide, etc. into a cross-sectional profile, and a layer of layers to form a three-dimensional shape. After the high-temperature sintering and copper-plating treatment, the formed part can obtain a metal body with a density of more than 92%, and the surface can be used as a mold after polishing and polishing.
Rapid mold manufacturing processes include laser selective melting (SLM), electron beam melting (EBM), and electron beam freeform fabrication (EBF), all of which utilize high energy to make powder materials selective. Melt to form a metal part. The shape-deposition manufacturing (SDM) rapid prototyping process developed by CarnegieMellon and Stanford University combines two methods of material growth and material removal. First, the droplet metal liquid is deposited as a solid layer according to the two-dimensional layer information of the CAD model, and then formed into a layer of precise size and shape by numerical control processing. The manufacturing process of each layer is a process combining micro-casting and numerical control processing. It has a broad development prospect in the rapid manufacture of large molds.
Rapid mold indirect manufacturing
Rapid mold indirect manufacturing uses rapid prototyping as a master and then uses other processes to replicate the required molds based on rapid prototyping. In fact, the practical basis of the process has long existed in the mold industry, that is, the mother mold or the sample piece is manufactured by various methods such as casting, spraying and electroforming, so that the technology development and application are very practical. Although the direct rapid molding method has few processes, the precision and performance of the mold are difficult to meet the requirements, and the indirect manufacturing method is a combination of a rapid prototyping and a conventional molding process, and a matching process of different complexity and cost can be selected according to the application requirements of the mold. The precision, surface quality, material requirements and mechanical properties of the mold are closer to the actual application. Therefore, the industry often uses the rapid mold indirect manufacturing method.
Powder molding
The most representative of the powder molding method is the 3DKeltool process developed by 3D Systems of the United States. This kind of process is a combination of SLA rapid prototyping technology, silicone rubber mold, powder molding and metal infiltration. Generally, the mold can be obtained in more than 10 days, which saves 25% to 40% of the cost compared with the CNC processing method. The performance and regularity of the mold material Steel molds are close and can be used for thermoplastics up to a million times. The disadvantage of this method is that the mold size is too large, and significant deformation occurs during the copper infiltration process, so it is only suitable for manufacturing small-sized mold inserts.
NCC manufacturing technology
The NCC (nickel-ceramic composite) process combines a nickel plating process with a ceramic composite backing. The method uses a polymer rapid prototyping as a master mold to plate a layer of nickel having a thickness of about 1 to 5 mm, and then filling a mixture of the ceramic powder and the organic binder on the outer surface of the nickel shell, and separating the prototype to obtain a mold. This composite mold is ideal for making larger molds (greater than 250mm@250mm@250mm) and up to 5,000 for injection parts.
Spraying method
Spraying is a common method of making metal molds. Since the rapid prototyping surface is subjected to thermal shock during the spraying process, the mechanical properties and thermal properties of the prototype are highly demanded. Generally, the spray material is a low melting point metal. If the prototype can withstand high temperatures, it can also be sprayed with a high melting point metal such as stainless steel. The indirect rapid mold manufacturing process of the spraying method is simple, and the fine grain surface of the mold cavity surface can be formed at one time, and the dimensional precision is high. The key issue is to solve the problem of adhesion and detachment of the coating to the rapid prototyping surface.
development trend
As the application range of rapid prototyping technology expands and the market demand for rapid product manufacturing increases, rapid mold manufacturing is bound to achieve rapid development. Rapid mold manufacturing technology has already demonstrated great advantages. Both domestic and foreign have invested a lot of power in development research, but the application is still not widely used, and there are still many constraints on its development and application. From the development situation in recent years, the future development trend of rapid mold manufacturing is reflected as:
(1) One of the main purposes of rapid mold manufacturing is to rapidly develop and produce molds for traditional manufacturing processes. In this regard, RT technology has made great progress, but there is still a certain gap from the requirements of practical applications. Therefore, it is necessary to further expand the application range of the rapid mold and reduce the manufacturing cost of the rapid mold. Especially for the rapid and low-cost manufacturing of large molds, it will become an important breakthrough direction for the rapid development of rapid molds.
(2) At present, rapid mold manufacturing uses traditional mold materials. Since rapid mold making is a new process, developing new mold materials and molding processes for its characteristics will become an important research direction, including new alloy materials and gradient functions. Materials, composites, etc.
(3) Compared with high-speed milling, rapid mold manufacturing has a metal mold with a fine and complicated shape on the surface, and it is difficult to omit the EDM process (ie, using RT instead of EDM). Fine and complex patterns straight (down to page 65) (continued on page 26) will form the future direction of RT technology.
(4) The use range and performance of indirect rapid molds such as metal shells + resin or ceramic backing are limited. The leading molds for injection, stamping and die casting of all metal materials will be developed rapidly with casting methods with high material flexibility. , occupying a major share of rapid mold indirect manufacturing. Combining surface treatment methods such as rapid prototyping, special casting, spray coating or electroless plating to produce high-performance rapid molds will have great advantages.
(5) Direct rapid mold manufacturing method, because it does not require intermediate processes and short process flow, after surface and dimensional accuracy, mechanical properties and mold types are improved, it will be more widely used, low cost and suitable for fine processing and The integration of stacking and removal molding technologies for a variety of materials will be rapidly developed. However, constraints in terms of materials and costs make the indirect method still the main process for rapid tooling.
(6) Indirect rapid manufacturing method is difficult to control. It is necessary to develop a rapid manufacturing process with short process and a small precision loss molding method to achieve stable working environment to improve the manufacturing precision of indirect method.
(7) In order to effectively improve the performance of rapid molds, computer-aided engineering (CAE) and virtual manufacturing techniques will be further adopted to optimize the selection and combination of mold materials and structural design of molds, and the quality and productivity of products are higher. .
Randm Tornado Vape,Randm Tornado Disposable,Randm Disposable Vape,Randm Tornado Vape Pod
Nanning Nuoxin Technology Co., LTD , https://www.nx-vapes.com