Rapid prototyping technology is based on the principle of discrete-superposition, which enables the rapid processing of prototypes or parts. Such products offer economic advantages and functionality in practice and have broad prospects for future development. This paper primarily explores the operational process, related technologies, and specific applications of rapid prototyping technology in mold manufacturing.
1. Overview of Rapid Prototyping Technology
1.1 Overview of Relevant Meanings
Rapid prototyping and manufacturing (RP) is a technology that emerged and developed in the late 1990s. Its main characteristic is the ability to effectively manufacture various relatively complex workpieces without the need for machining equipment or molds. This offers advantages in small-batch production or new product development, saving time and reducing initial investment. The core working principle of rapid prototyping is the discrete-superposition principle. Rapid prototyping prototypes and related rapid prototyping parts are not specific to any particular product; their specific uses differ. Rapid prototyping prototypes refer to all experimental parts with relevant properties and functions, primarily used for testing new products, and their overall production quantity is relatively small. Rapid prototyping parts, on the other hand, are the final product, a ready-to-use product model, but manufactured rapidly in practice. Both prototypes and rapid prototyping parts are widely used in production, but their functions differ. In practice, manufacturers choose based on their specific needs and may use both together.
1.2 Rapid Prototyping (RP) Technology: Specific Molding Operation Process
First, a 3D model of the relevant production model is constructed using CAD software on a computer. This is the first step in the entire workflow and has a direct impact on subsequent operations. If the model is not complete, it will inevitably have a certain impact on the subsequent work.
Secondly, the completed model is sliced layer by layer in the computer for simulation. During this process, a certain degree of realism must be ensured, with slicing operations performed along the same force and direction as much as possible. Different slicing directions should be avoided each time to prevent unnecessary problems in future development. Thirdly, the information from the sliced layers in the computer is transmitted and integrated with the rapid prototyping system for control, ensuring that the raw materials can be processed layer by layer. Through superposition, a three-dimensional solid is achieved.
Finally, an actual part is formed.
With the development of the times, this technology has been fully developed and its application scope is relatively wide. It can be applied in related fields such as automobile manufacturing, aerospace construction, building and health care, and its development prospects are relatively good.
1.3 Rapid Prototyping Classification
In the current market, rapid prototyping technology encompasses a wide variety of development processes. These can be categorized based on the materials used or the molding method. Those using lasers or other light sources can be classified as Stereoscopic Modeling (SL), Photopolymerization Rapid Prototyping, Layered Solid Modeling (LDM), Selective Laser Sintering (SLS), and Shape Deposition Modeling (SDM). Based on raw material jetting processes, they can be categorized as Fused Deposition Modeling (FDM) and Taper Printing (3DP). Other categories include Thermopolymer Polymerization (LTP), Solid Gel Mask Molding (SGC), Ballooning Particle Molding (BFM), Space Forming (SF), and Solid Sheet Molding (SFP).
2. Exploration of Relevant Processes in Rapid Prototyping Die Manufacturing
2.1 Rapid Prototyping Process Mode
First, stereolithography technology
The main working principle of SLA is to use an ultraviolet laser as the primary energy source to slice the designed three-dimensional models.
In practice, the operation mainly involves using helium-ion lasers and helium-ion lasers. These lasers have different wavelengths and powers, allowing for flexible application based on the specific situation. During the model slicing process, relevant layer information is understood, and then the computer processes this information. Through laser scanning, some liquid photosensitive resin within the area is transformed into a solid form, creating a relatively thin solid cross-section. In subsequent operations, the worktable height is lowered, and the layers are stacked one by one to complete the entire model creation.
After the model is made, it needs to be hardened to prevent damage. After hardening, it is then polished, electroplated, and painted to improve its appearance. Once it is checked and approved, it can be packaged and sold.
Second, the model thin-film laminate forming technology mode
Thin-film lamination technology shares some similarities with stereolithography in practice, both using lasers. However, the first involves cutting and bonding the raw paper using lasers, while the second uses lasers to solidify liquid photosensitive resin. The final products also differ: the first produces a model of a part, while the second produces a complete model. In actual manufacturing, both methods involve layering and continuous descent of the worktable throughout the process.
In actual operation, the specific steps of this god mode are as follows:
First, sheets of paper coated with hot melt adhesive on one side are bonded together under pressure. Using data from a CAD model, a computer controls a laser to cut the paper, creating a template of the inner and outer contours of the parts to be cut. Second, a new sheet of paper is added, and the above steps are repeated. Throughout the manufacturing process, careful attention must be paid to the paper cutting. The paper must remain stationary during the descent of the worktable; therefore, meticulous attention must be paid to the support and curing process of the paper.
This technology has the advantages of relatively high molding speed in practice, which can effectively save time and ensure the effective implementation of overall production and investment. At the same time, its overall investment cost is relatively low. Even if operational errors occur during the production process, it will not cause serious investment losses, and its overall quality is fundamentally guaranteed.
Third, selective laser sintering (SLS) technology.
This technology primarily utilizes laser beams, and its working principle is layer-by-layer manufacturing. During the manufacturing process, the laser beam selectively fuses relevant metal and non-metal powders on a worktable. After sintering, a mold cross-section is formed. Following the same principle, a layer of powder is laid on top, and then sintered again using the laser beam, thus creating a three-dimensional solid layer by layer. The advantage of this technology is that it allows for direct powder sintering, eliminating the need to melt and shape the powder beforehand. This technology has a wide range of applications in practice, and most materials can be manufactured using this method.
Fourth, Fused Deposition Modeling (FDM) technology.
The main raw material used in this technology is not metal powder, but rather wire. This wire needs to be melted before it can be used. During operation, it is melted in the nozzle and then subjected to subsequent processing.
Fifth-dimensional printing technology (TDF)
This technology does not require laser technology in practice. It mainly uses a nozzle to spray relevant liquid materials to form a three-dimensional solid. The operation requires certain requirements for the material, which must have a certain degree of plasticity to ensure that it can be formed into a solid. This technology is commonly used in the production of ceramics.
2.2 Rapid Prototyping Die Manufacturing
First, directly manufacture the relevant metal molds.
For parts with relatively short production time requirements and a relatively small overall quantity requirement, the best approach is to manufacture them directly. This method mainly involves casting the shell using laser sintering. In practice, the first step is to create CAD drawings of the molds that form the shell, and then manufacture the shell.
The CAD drawing of the mold shell itself is mainly created and processed based on computer CAD software. After being supplemented and improved, a mold shell is formed. The mold shell is mainly completed by SLS sintering during the furnace process. After the powder is cleaned, a mold shell is obtained. The advantage of this method in practice is that it can ensure that a relatively complex operation is completed in a short time. It can be said that the more complex the part model, the more its inherent advantages can be fully demonstrated in the manufacturing process.
Second, the method of indirectly manufacturing metal molds
Rapid prototyping can also be used in practice to indirectly create molds. Indirect mold creation involves obtaining the outline and shape of the mold through hard molds or by spraying metal, or by replicating a master mold. Rapid prototyping technology can also process the surface of the prototype to replace the original wooden mold for direct mold creation, or transition the prototype into a paste model or ceramic model before casting the corresponding metal model.
Third, applications of rapid prototyping mold manufacturing
Rapid prototyping technology primarily employs two manufacturing modes: direct and indirect. The choice of manufacturing process depends on the specific application and scenario, but the quality of the produced product remains consistent. Direct manufacturing is mainly used in laser sintering. This method produces molds with a relatively long lifespan, but the sintering process can cause material shrinkage, which is uncontrollable and leads to a lack of precision in the molds, requiring repeated verification and inspection. Indirect manufacturing is a frequently used method in rapid mold making. Due to various constraints and influences, some resulting molds may not be able to replace the original finished product, necessitating systematic inspection.
In future development, soft molds, as a type of rapid prototyping mold, have certain development prospects. In practice, due to the special characteristics of the materials used, they are fundamentally different from traditional steel materials. Overall, their product manufacturing costs are relatively low and the cycle is relatively short. Therefore, they can be applied in the fields of defense and aviation during the development of related new products. They are suitable for the production of models with small batch sizes, many types, and high-speed modifications. At present, the main production methods of soft molds are silicone rubber casting, metal spraying, and resin casting.
Although soft molds have certain advantages in application, their specific scope of use is also limited. In some large-scale product manufacturing processes, hard molds are still required. Hard molds are steel molds. Existing rapid prototyping technologies for steel molds mainly include investment casting, electrical discharge machining, and ceramic mold precision casting.
In practical applications, the selection and manufacture of relevant production molds should be made in a reasonable manner according to specific needs and related production requirements, so as to improve the overall work quality and efficiency, ensure the scientific nature of the overall production funds and cost investment, and effectively improve the overall quality.
3. Conclusion
In current development, rapid manufacturing has progressed relatively quickly internationally, with significant expansion in materials, processes, and equipment. This signifies that rapid manufacturing is gradually becoming a new production method. The application of rapid manufacturing techniques in related manufacturing molds has also developed. However, from an overall perspective, the quality and lifespan of rapid manufacturing molds cannot meet the demands of large-scale production. While it is used in the trial production and small-batch production of some products, it is believed that this technology will be widely applied in the future.
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