Epoxy resin mold is also called resin mold. It has short manufacturing cycle, low cost, and is especially suitable for products with complex shapes and rapid product replacement in the industrial field; therefore, it has been widely used in advanced foreign countries, especially in the automobile manufacturing industry. , Toy manufacturing, home appliance manufacturing, hardware industry and plastic products and other industrial systems are more popular. According to different structures and uses, epoxy resin molds are made of epoxy resin, curing agent, toughening agent and filler (iron powder, aluminum powder, silicon powder, barite powder, etc.) with various properties to make mold resin. It is made of glass fiber cloth and carbon fiber cloth as reinforcement materials.
Epoxy resin molds can be designed with different epoxy mold resin formulation components according to different uses and technical requirements. According to the actual application statistics of epoxy resin molds at home and abroad, epoxy resin is suitable for making the following types of molds. In terms of cold pressing molds, there are: bending molds, drawing molds, falling hammer molds, casting molds, etc.; Molds include: plastic injection molds, wax injection molds, blow molds, blister molds, foam molding molds, leather plastic product molding molds, etc. The manufacturing characteristics of epoxy resin molds are simple, fast, and low-cost; for example, some metal molds with complex shapes and difficult to form are made of epoxy resin. They can be formed at one time without large-scale precision. Cutting machine tools can also be used without advanced fitter. The manufacturing cycle of some metal molds takes several months to half a year. It usually takes 3 to 5 days to complete with epoxy resin molds. The cost is only about 15-20% of that of steel molds, and resin molds have a long service life and wear. It can be repaired quickly and continue to use. Therefore, the manufacture of epoxy molds is a new technology, new material and new process that breaks the traditional machining process. Epoxy resin molds are manufactured by specialized research and development centers set up by large factories abroad, but domestically, they are only developed by defense industry units. General factories and enterprises lack the manufacturing technology and formulas in this area. The application, popularization and development of molds are slow. In the future, with the development of new materials and new technologies, the promotion of epoxy resin application technology, the comprehensive performance and manufacturing technology of epoxy resin molds are widely introduced and understood, the performance of epoxy resin composite materials is improved, and the manufacturing process of resin molds With the simplification of the application process, the epoxy resin mold will inevitably be developed by leaps and bounds and become a new high-efficiency, low-cost advanced mold.
Second, the type of epoxy mold
1. Epoxy resin cold pressing type mold
(1) Bending die, forming die, drawing die, slit die, etc.
Epoxy resin composites are mainly used to make concave and convex molds, which can be formed by casting or low-pressure compression molding. It can punch or draw aluminum plates with 0.8 mm steel plates and 2 mm or less, with a life of more than 10,000 times without wear. For large drawing dies, such as car cab roof parts, the use of epoxy resin to make molds shows greater advantages, without the need for large cutting machine tools. The notch mold is used to manufacture large-scale parts with complex structure, and a steel strip is embedded in the cutting edge of the concave and convex mold. Bending molds made of epoxy resin. The stamping parts include ceiling fan blades. The size of the fan blades is very demanding. Because of the air volume and use effect, the epoxy resin mold is fixed on a 100-ton punch. The number of press forming has reached more than 300,000 times, and resin molds are still in use.
（2) Drop hammer die
Using epoxy resin drop hammer die, it can punch 2.5 mm thick aluminum plate and 1.5 mm thick stainless steel plate. The mold made of resin has good coordination performance, simple process, short manufacturing cycle, 3/4 time shorter than aluminum-zinc mold, and can save a lot of non-ferrous metals and reduce costs.
With regard to molds such as models, core boxes, templates, etc., the advantages of using epoxy resin to make molds:
① The resin mold manufacturing cycle is short, for example, the aluminum mold manufacturing cycle is about one month, while the resin mold manufacturing only takes 3 to 5 days
② The resin mold has a long service life. For example, the aluminum mold must be overhauled after 2,000 times, while the resin mold can be used up to 20,000 times;
③ Resin mold repair is simple and convenient;
④ The resin mold has light weight and high labor productivity.
Therefore, epoxy resin is widely used to make molds in China, both at home and abroad. Structure: There are resin-coated compound molds and all-resin integral molds.
In addition, epoxy resin can also be used to make hammering molds, explosive forming molds, hydroforming molds, stretch mold tires, shifting molds, inspection molds, etc. Most of the above resin molds are used to make airplanes, cars or rockets. The other parts. Epoxy resin molds have fast manufacturing speed, low cost and good coordination performance, which can solve the technical difficulties in general metal mold manufacturing.
2. Epoxy resin hot pressing type mold
(1) wax injection mould
Used for injection wax molds, generally made of metal molds, and plaster molds are also used for small batches and low requirements. First, use a wax injection mold to inject the wax shape, then make a shell mold according to the wax shape, and then pour the metal after melting the wax. The resin wax injection mold has high strength, convenient molding, high smoothness, good abrasion resistance, and poor thermal conductivity. When processing the sculptured surface, the economic benefit is higher.
(2) Plastic injection mould
With the rapid development and wide application of engineering plastics, the manufacturing of plastic molds has become more important. Epoxy resin injection mold is a new technology that is making a breakthrough at home and abroad. According to the information, the epoxy resin injection mold is a simple and fast mold abroad because of its fast molding and precise appearance, but the disadvantage is poor heat resistance. Therefore, cooling water pipes should be considered in the design of resin molds to increase the number of injections. . Several units in our country are also developing this type of resin mold, and have achieved good applications. The number of injections has reached more than 10,000 times, and the epoxy mold surface has not changed. The optimization of the resin mold formulation design and the improvement of the mold structure make the thermal strength and thermal conductivity of the resin mold have a higher level. Therefore, if the product surface is a sculptural surface, which is simply impossible to be processed by machining, the superiority of the epoxy mold is even more demonstrated.
(3) Blow mold and blister mold
This kind of mold requires epoxy resin formula cured product to have good thermal strength and thermal conductivity. Its biggest advantage is convenient forming. These resin molds are all molds in development and application.
3. Materials and properties of epoxy resin molds
Phenolic resins, unsaturated polyester resins, epoxy resins, etc. are used as the base resins for making resin molds. Among these matrix resins, epoxy resin has the best mechanical and physical properties and good manufacturability. Therefore, epoxy resin is used to make molds. For example, the highest-strength composite materials are made of epoxy resin, boron fiber, and carbon fiber.
Matrix resin: commonly used epoxy resins are bisphenol A epoxy resin, such as; YD-128, E-51, E-44, etc.; novolac epoxy resins F-44 and F-45; amino multifunctional epoxy Resin AFG-80, AFG-90; alicyclic epoxy resin R-122, etc. According to the mechanical strength requirements, heat resistance requirements and precision requirements of different resin molds, select the type of matrix resin, and then design the formula.
Curing agent: Amine curing agent: aliphatic amine, polycondensation amine, aromatic amine, modified aromatic amine, etc.;
Imidazole curing agent: 2-methylimidazole, modified imidazole, 2-ethyl-4-methylimidazole, etc.;
Acid anhydride curing agent: methyltetrahydrophthalic anhydride, modified methyltetrahydrophthalic anhydride, chloro-bridged acid anhydride, pyromellitic dianhydride, etc.
Toughener: LDY-050 active toughener, LDY-052 reactive toughener, LDY-055 sea-island structure toughener, high polymerization degree polysulfide rubber, carboxy-terminated nitrile rubber, etc.
Fiber reinforced materials: glass fiber (cloth), carbon fiber (cloth), boron fiber (cloth), etc.
Filling: silica powder, iron powder, aluminum powder, copper powder, alumina powder, barite powder, etc.
Epoxy resin mold composite material is composed of matrix resin, curing agent, toughening agent, filler and fiber reinforced material, etc., which can be cured to achieve high performance mold resin. According to the different structure and technical requirements of different molds, different formulas are designed and the formulas are different, and the forming process and curing process are also different.
Typical mechanical and physical properties of epoxy resin mold formula pouring body:
Compressive strength: 120～150 MPa
Impact strength: 25～38 KJ/m2
Bending strength: 110～160 MPa
Brinell hardness: 20～30 MPa
Shrink 0.2～0.5% during curing
Fourth, the process method of manufacturing epoxy resin mold
1, casting process manufacturing
Weigh and mix according to the epoxy resin formula ratio, then pour it into the model mold, and use room temperature or high temperature curing according to the formula process requirements. Vibration casting process can also be used.
2, lamination process manufacturing
Glass fiber or carbon fiber reinforced epoxy resin mold does not require pressure during curing. The fiber reinforced material is layered in the mold and the epoxy resin mixture is applied layer by layer, which is called the contact lamination process. When curing is carried out under pressure, the content of glass fiber can be increased, which is called pressure lamination process.
3. The mixture of short glass fiber reinforcement and resin can be formed in a simple metal mold.
In short, for different molds, different epoxy resin formulations and manufacturing processes can be designed according to the mold structure, mold type, and mold technical requirements to produce a good epoxy mold.