Table 1 RIM molding common product defects and countermeasures
Originated in the polyurethane reaction injection molding plastic. As technology advances, the process also extended to a variety of materials processing. At the same time, in order to broaden the application of RIM technology in the field, especially in the automotive industry in the application, the process also introduces a fiber-reinforced technology.
About RIM
Reaction Injection Molding (the "RIM") refers to the high chemical activity, low molecular weight material by the impact of two-component mixture at room temperature under low pressure into the closed mold to complete the polymerization, chemical crosslinking and curing reaction and the formation of products of the process. This polymerization and injection molding will be a combination of new technology, material mixed with high efficiency, mobility, and preparation of raw materials flexibility, short production cycle and low cost, suitable for large-scale production of thick-walled products, therefore the world has been attention.
RIM polyurethane material used only for the first, with the advances in technology, RIM also be applied to a variety of materials (such as epoxy, nylon, polyurea and dicyclopentadiene, etc.) processing. Rubber and metal forming for the RIM process is the current hot research.
RIM to broaden the application areas, to improve rigidity and strength of RIM's products, making structural products, RIM technology has been further developed, there has been enhanced products designed to enhance the shape of the reaction injection molding (RRIM) and dedicated structural parts forming the structure of reaction injection molding (SRIM) technology. RRIM and SRIM molding process works the same with the RIM, the main difference is that fiber-reinforced composite material preparation. Currently, the typical RIM products are car bumpers, fenders, body panels, truck containers, truck doors and door components and other large products. The quality of their products better than the SMC products, production speed, a smaller amount of secondary processing required.http://www.prmindustry.com/Abstract...Articles section RIM molding process
1 process
RIM process as follows: monomer or prepolymer in a liquid state by the metering pump to a certain ratio into the mixing head for mixing. Mixture into the mold, the mold rapid crosslinking reaction and, after stripping for RIM products. This process can be simplified to: store → measurement → mixed → filling → curing → → top of post-processing.
(2) process control
(1) storage. RIM technology used by the two components are usually liquid at certain temperatures were stored in two reservoirs, the reservoir is generally pressure vessel. Not formed when the liquid is usually 0.2 ~ 0.3 MPa of low pressure in the reservoir, heat exchanger and the mixing head in constantly circulating. Of polyurethane, the liquid temperature is generally 20 ~ 40 ℃, temperature control accuracy of ± 1 ℃.
(2) measurement. Two sub-liquid measurement generally done by the hydraulic system, hydraulic system consists of pumps, valves and accessories (control liquid materials distribution piping system and control the work of oil tank system) is composed. After injection of high voltage switching devices need to be converted to injection pressure of the pressure required. Quantitative pump hydraulic liquid measured output, required measurement accuracy of at least ± 1.5%, the best control in ± 1%.
(3) mixed. In the RIM molding, the product quality is good or bad depends largely on the mixing head of mixed quality, production capacity depends entirely on the mixing head of mixed quality. Generally use the pressure of 10.34 ~ 20.68MPa, in this pressure range to get better mixing.
(4) filling. Reaction injection mold filling material is characterized by high material flow rate. The requirement of liquid viscosity is not too high, for example, polyurethane filling mixture when the viscosity of 0.1Pa.s so.
When the material system and the mold is determined. Important process parameters is only two, namely, filling time and material temperature. Polyurethane material shall not exceed the initial temperature of 90 ℃, the cavity should generally not exceed the average velocity 0.5m / s.
(5) curing. Two-component polyurethane mixture into the mold cavity after the highly reactive, in a very short period of time to complete cure stereotypes. However, due to poor thermal conductivity of plastics, a lot of reaction heat can not be distributed, therefore the material forming the internal temperature is much higher than the surface temperature, resulting in the forming material to cure from the inside out. To prevent the cavity of the temperature (not higher than the resin, the thermal decomposition temperature), should give full play to the mold to distribute the heat exchanger function.
Reaction Injection-mold curing time, mainly by forming the material formulation and product dimensions. In addition, reaction injection products emerge from the mold after the heat treatment needed. Heat treatment has two effects: first, add curing, and second, after painting bake in order to form a solid surface products, protective film or decorative film.
(6) forming the causes of defects in products and solutions. RIM products, the causes of defects and solutions in Table 1.
RIM mold and product design
1 mold
(1) pouring system. Gating system, also known as "injection system", by the gate, runner, and vent components. During RIM mold design, molding gate shape and height depending on the thickness and cavity flow products. Large mold is usually straight rod-like gate should be adopted, while the small-capacity molds are advised to use fan-shaped gate.
The location of the main channel should be located in a mold, it should be noted, in determining the flow position, make sure the materials from the products of cross-section of the lowest into the cavity. The location of vents should be located in the material flow at the end, so that injection of air out of the cavity.
(2) mold temperature control system. RIM here only as an example to illustrate the metal mold. Mold temperature control method is usually buried in the mold tube, into the water through the heating or cooling. Metal mold thickness should be 50mm, while the casing for processing resin pitch to vary. Typically, the polyurethane RIM's mold temperature of 40 ~ 80 ℃, mold temperature control accuracy of ± 4 ℃, preferably ± 1 ℃. Tube spacing of 80 ~ 100mm, parietal cooling holes and the distance between the mold should be 9.5mm.
(3) sub-surface. Of sub-surface location is set there is a general requirement that the sub-surface position of the parts in the processing of contours near the bottom a little, it will give the cavity is inflated and filled with the material to the cavity of the residual air exhaust to the outside mold .
2. Product Design
(1) Thickness. The same as with conventional injection products, RIM products during the design wall thickness, wall thickness should be avoided as too thick or too thin. RIM polyurethane foam products, for example, conventional wall thickness should be controlled at 6.35 ~ 12.7mm, 12.7mm when the wall thickness is greater than or less than 3.17mm, the appropriate remedial measures should be taken.
(2) to strengthen the tendons. The purpose of using ribs to improve rigidity and strength products. Should be used in thin and long ribs, avoid using thick and short ribs. Ribs should be placed along the flows of materials is appropriate, this will not affect the material flow of the gas emissions.
(3) stripping slope. RIM products, stripping slope should choose 2 °, is too big or too small is not conducive to product stripping.
(4) rounded corners. RIM products within the radius of not less than 3.175mm, the external radius of not less than 1.578mm.
(5) Boss. Boss should be 2 ° of the stripping slope and along the periphery or within the muscle arrangement of parts, if the boss of the design height of more than 6.57mm, you must be complemented by the support plate. In the import Kong Zhongcheng type, must accurately determine the self-tapping screw threads and positioning the location. Boss and into the hole the size of the stripping strength for the great influence, should be addressed.
A wide range of RIM technology
1 polyurethane RIM
Polyurethane RIM materials used and general-purpose polyurethane raw materials is different: the requirements of low viscosity liquid materials, good liquidity and high reactivity, and raw materials should be made into A (polyol), B (two cyanuric ester) two points. The process includes: the A, B two points of raw materials were placed in tanks in the injection machine, and make them in N2 atmosphere, at a certain temperature to maintain proper viscosity (1Pa · s or less) and reactivity; two points with a quantitative pump pressure by a certain percentage of raw materials into the mixer and injected into the sealed mold; rapid polymerization mixture in the mold, curing. In this process, from raw materials to fill the cavity pressure of only 1 ~ 4s, and complete production cycle, compared with 30 ~ 120s.
2. Polyurethane RRIM
Polyurethane RRIM technology is used in two-component polyol and isocyanate. Polyols polyether type, relative molecular mass of 1? 800 ~ 2? 400, functionality of 2 to 3; isocyanate generally methylene diphenyl diisocyanate (MDI) or isocyanate and mixtures of isomers, functional 2 to 7 degrees. RRIM reinforced materials are mainly two, namely, chopped reinforcing fibers and the ground enhanced fiber. Fiber length is generally 1.5 ~ 3.0mm, length can guarantee to enhance this effect, and also to facilitate the system by injection. The greater dispersion of the fiber length, the worse the effect is enhanced. RRIM products in enhanced fiber content (mass fraction) is generally below 20%, for the special requirements of high-strength products to enhance the fiber content of up to 50%.
3. Epoxy RIM
Epoxy resin is the second thermosetting polyurethane RIM developed after another species. Two-component epoxy and polyurethane RIM RIM process roughly the same. Epoxy resin and curing agent ratio and process conditions in Table 2.
RIM products epoxy tensile strength and flexural modulus, low coefficient of linear expansion, and has excellent chemical resistance and high heat resistance (as compared with polyurethane and nylon). In order to improve the impact strength of epoxy resin can be added to the raw materials base with isocyanate, relative molecular mass of 4? 000 polyethylene glycol prepolymer.
In addition, to further improve the mechanical properties, but also adding a variety of reinforcing materials, such as various fiber, whisker powder, flakes, beads and other materials and long fibers, making RRIM products, their applications in the automotive industry very competitive.
4. Nylon 6 RIM
Nylon 6 RIM raw materials used include polyether polyols and a catalyst made from the prepolymer (A component) and caprolactam (B component). Processing, raw materials can first join caprolactam, the control temperature of 74 ~ 85 ℃, then add the catalyst, closed container, strong mixing of the catalyst dissolved in caprolactam, the mixture degassed under N2 15min. Caprolactam and then the prepolymer blend, temperature 74 ~ 85 ℃, stir well before degassing. Then under pressure, two liquid components through the mixer into the mold, curing. As occurred in the prepolymer and block copolymerization of caprolactam, which derived products, flexible, high impact strength.
Added reinforcement of nylon 6 RRIM products, higher rigidity, low coefficient of linear expansion. Nylon 6 RIM and RRIM products use a wide, mainly for the automotive industry, such as fenders, doors, hood and bumper cover.
5. Dicyclopentadiene (DCPD) RIM
DCPD RIM raw materials including DCPD, catalysts, activators, stabilizers, modifiers, fillers, antioxidants, elastomers, foam, fire retardants and nucleating agents.
In the DCPD RIM system, will generally be divided into various raw materials required by formula A, B two points, A component including DCPD, catalysts, stabilizers and other additives. B component including DCPD, activators, regulators and other additives.
Processing, the accurate measurement of A, B two points in the mixing head after mixing, was injected into the sealed mold, the mold rapid polymerization occurs, followed by curing. Need special attention, in the mold is not filled before the polymerization time modifier to control chemical reactions. After the mold is full, about 10s to complete the polymerization and molding. Products generally do not need to go through after the aging process.
6. Polyurea RIM
Polyurea RIM uses a mold with the material from the release agent within the system, forming by the end of amino polyether, amine chain extenders and isocyanate end groups of the prepolymer (MDI) reaction made polyurea. The process has many excellent features: As the amine and isocyanate reactivity, hence no catalyst; reactants into the mold cavity when the viscosity, while reducing the vortex filling, so little into the air, products scrap rate; material into the mold after 1 ~ 2s occurs within the gel, just to stay in the mold 20s; mold cavity when the material does not stick, use less restricted within the release agent system; prepared by adding glass fiber to enhance Polyurea RRIM products, the amine and isocyanate for the reaction between the no effect.
Polyurea generated throughout the reaction process does not require a catalyst, making the products in no residual catalyst, therefore polyurea RIM products do not degrade at high temperatures, product stability.
Terminal amino polyether diamine chain extenders and MDI's fast response. To control the reaction in the state, part of polyether polyols can be modified to the MDI prepolymer made a half, thereby reducing the speed of the reaction between the material, slowing the response speed of the gel material. Also, by adjusting the isocyanate group content travel divorced, can be obtained with different bending elasticity modulus polyurea RIM products. The Dow Chemical Company SPECTRIMTMHT series polyurea performance in Table 3.
7. Mat molding RIM
Will enhance the fiber mat piece, pre-placed in the mold, and then, two sub-hit by high-pressure low-viscosity liquid mixture and injected into the cavity. In the cavity, the mixed liquid impregnated fiber mat formed by the reaction products and film, this molding method is known as "Mat molding RIM (MM / RIM)". ARIMA × 1000 is the Ashland developed MM / RIM product, its performance is shown in Table 4.
8. Variable fiber reaction injection molding (VFRIM)
MM / RIM technology is the first fiber laid in the mold cavity, and then injected into the liquid resin. The disadvantage of this process is the need to pre-mat, so that complicated processes, increase costs. In addition, as required by hand shop mat, but also greatly increased the labor intensity. Based on this, and gave birth to a variable fiber reaction injection molding (Variable fiber injection reaction injecction molding, VFRIM).
This technology was developed by Krauss-Maffei in Germany and Italy Cannon-Technos in the 1990s development. The important feature of the first fiber roving into the shredding machine, cut into short fibers dispersed, then the short fibers mixed into the L-shaped head, the mixing with the resin, and finally the mixture into the mold for curing.
Now use technology products VFRIM a car door, cushion trays, bumper, sun visor, luggage tray and light truck box panels. Tables 5 and 6 are typical of low-density and high density VFRIM products and compare the performance of traditional R1M products. It can be seen, the use of technology to produce low-density products VFRIM performance and very traditional RIM products. The use of VFRIM technology to produce high-density product compared with RIM products, showed a better performance.
VFRIM one of the advantages of technology is that by adjusting the fiber chopper, you can control the fiber length, intensity and amount of fiber roving, fiber in the products to control the distribution. The second advantage is the significant cost reductions. Fiber roving cost than conventional SRIM technology for glass fiber mat 60% lower. By reducing the spread of glass fibers into the mold process, the cost is correspondingly reduced; in the injected resin / glass fiber mixture, due to precise control and reduce waste. These combined factors make the production costs, which is the main advantage of the technology.
About RIM
Reaction Injection Molding (the "RIM") refers to the high chemical activity, low molecular weight material by the impact of two-component mixture at room temperature under low pressure into the closed mold to complete the polymerization, chemical crosslinking and curing reaction and the formation of products of the process. This polymerization and injection molding will be a combination of new technology, material mixed with high efficiency, mobility, and preparation of raw materials flexibility, short production cycle and low cost, suitable for large-scale production of thick-walled products, therefore the world has been attention.
RIM polyurethane material used only for the first, with the advances in technology, RIM also be applied to a variety of materials (such as epoxy, nylon, polyurea and dicyclopentadiene, etc.) processing. Rubber and metal forming for the RIM process is the current hot research.
RIM to broaden the application areas, to improve rigidity and strength of RIM's products, making structural products, RIM technology has been further developed, there has been enhanced products designed to enhance the shape of the reaction injection molding (RRIM) and dedicated structural parts forming the structure of reaction injection molding (SRIM) technology. RRIM and SRIM molding process works the same with the RIM, the main difference is that fiber-reinforced composite material preparation. Currently, the typical RIM products are car bumpers, fenders, body panels, truck containers, truck doors and door components and other large products. The quality of their products better than the SMC products, production speed, a smaller amount of secondary processing required.http://www.prmindustry.com/Abstract...Articles section RIM molding process
1 process
RIM process as follows: monomer or prepolymer in a liquid state by the metering pump to a certain ratio into the mixing head for mixing. Mixture into the mold, the mold rapid crosslinking reaction and, after stripping for RIM products. This process can be simplified to: store → measurement → mixed → filling → curing → → top of post-processing.
(2) process control
(1) storage. RIM technology used by the two components are usually liquid at certain temperatures were stored in two reservoirs, the reservoir is generally pressure vessel. Not formed when the liquid is usually 0.2 ~ 0.3 MPa of low pressure in the reservoir, heat exchanger and the mixing head in constantly circulating. Of polyurethane, the liquid temperature is generally 20 ~ 40 ℃, temperature control accuracy of ± 1 ℃.
(2) measurement. Two sub-liquid measurement generally done by the hydraulic system, hydraulic system consists of pumps, valves and accessories (control liquid materials distribution piping system and control the work of oil tank system) is composed. After injection of high voltage switching devices need to be converted to injection pressure of the pressure required. Quantitative pump hydraulic liquid measured output, required measurement accuracy of at least ± 1.5%, the best control in ± 1%.
(3) mixed. In the RIM molding, the product quality is good or bad depends largely on the mixing head of mixed quality, production capacity depends entirely on the mixing head of mixed quality. Generally use the pressure of 10.34 ~ 20.68MPa, in this pressure range to get better mixing.
(4) filling. Reaction injection mold filling material is characterized by high material flow rate. The requirement of liquid viscosity is not too high, for example, polyurethane filling mixture when the viscosity of 0.1Pa.s so.
When the material system and the mold is determined. Important process parameters is only two, namely, filling time and material temperature. Polyurethane material shall not exceed the initial temperature of 90 ℃, the cavity should generally not exceed the average velocity 0.5m / s.
(5) curing. Two-component polyurethane mixture into the mold cavity after the highly reactive, in a very short period of time to complete cure stereotypes. However, due to poor thermal conductivity of plastics, a lot of reaction heat can not be distributed, therefore the material forming the internal temperature is much higher than the surface temperature, resulting in the forming material to cure from the inside out. To prevent the cavity of the temperature (not higher than the resin, the thermal decomposition temperature), should give full play to the mold to distribute the heat exchanger function.
Reaction Injection-mold curing time, mainly by forming the material formulation and product dimensions. In addition, reaction injection products emerge from the mold after the heat treatment needed. Heat treatment has two effects: first, add curing, and second, after painting bake in order to form a solid surface products, protective film or decorative film.
(6) forming the causes of defects in products and solutions. RIM products, the causes of defects and solutions in Table 1.
RIM mold and product design
1 mold
(1) pouring system. Gating system, also known as "injection system", by the gate, runner, and vent components. During RIM mold design, molding gate shape and height depending on the thickness and cavity flow products. Large mold is usually straight rod-like gate should be adopted, while the small-capacity molds are advised to use fan-shaped gate.
The location of the main channel should be located in a mold, it should be noted, in determining the flow position, make sure the materials from the products of cross-section of the lowest into the cavity. The location of vents should be located in the material flow at the end, so that injection of air out of the cavity.
(2) mold temperature control system. RIM here only as an example to illustrate the metal mold. Mold temperature control method is usually buried in the mold tube, into the water through the heating or cooling. Metal mold thickness should be 50mm, while the casing for processing resin pitch to vary. Typically, the polyurethane RIM's mold temperature of 40 ~ 80 ℃, mold temperature control accuracy of ± 4 ℃, preferably ± 1 ℃. Tube spacing of 80 ~ 100mm, parietal cooling holes and the distance between the mold should be 9.5mm.
(3) sub-surface. Of sub-surface location is set there is a general requirement that the sub-surface position of the parts in the processing of contours near the bottom a little, it will give the cavity is inflated and filled with the material to the cavity of the residual air exhaust to the outside mold .
2. Product Design
(1) Thickness. The same as with conventional injection products, RIM products during the design wall thickness, wall thickness should be avoided as too thick or too thin. RIM polyurethane foam products, for example, conventional wall thickness should be controlled at 6.35 ~ 12.7mm, 12.7mm when the wall thickness is greater than or less than 3.17mm, the appropriate remedial measures should be taken.
(2) to strengthen the tendons. The purpose of using ribs to improve rigidity and strength products. Should be used in thin and long ribs, avoid using thick and short ribs. Ribs should be placed along the flows of materials is appropriate, this will not affect the material flow of the gas emissions.
(3) stripping slope. RIM products, stripping slope should choose 2 °, is too big or too small is not conducive to product stripping.
(4) rounded corners. RIM products within the radius of not less than 3.175mm, the external radius of not less than 1.578mm.
(5) Boss. Boss should be 2 ° of the stripping slope and along the periphery or within the muscle arrangement of parts, if the boss of the design height of more than 6.57mm, you must be complemented by the support plate. In the import Kong Zhongcheng type, must accurately determine the self-tapping screw threads and positioning the location. Boss and into the hole the size of the stripping strength for the great influence, should be addressed.
A wide range of RIM technology
1 polyurethane RIM
Polyurethane RIM materials used and general-purpose polyurethane raw materials is different: the requirements of low viscosity liquid materials, good liquidity and high reactivity, and raw materials should be made into A (polyol), B (two cyanuric ester) two points. The process includes: the A, B two points of raw materials were placed in tanks in the injection machine, and make them in N2 atmosphere, at a certain temperature to maintain proper viscosity (1Pa · s or less) and reactivity; two points with a quantitative pump pressure by a certain percentage of raw materials into the mixer and injected into the sealed mold; rapid polymerization mixture in the mold, curing. In this process, from raw materials to fill the cavity pressure of only 1 ~ 4s, and complete production cycle, compared with 30 ~ 120s.
2. Polyurethane RRIM
Polyurethane RRIM technology is used in two-component polyol and isocyanate. Polyols polyether type, relative molecular mass of 1? 800 ~ 2? 400, functionality of 2 to 3; isocyanate generally methylene diphenyl diisocyanate (MDI) or isocyanate and mixtures of isomers, functional 2 to 7 degrees. RRIM reinforced materials are mainly two, namely, chopped reinforcing fibers and the ground enhanced fiber. Fiber length is generally 1.5 ~ 3.0mm, length can guarantee to enhance this effect, and also to facilitate the system by injection. The greater dispersion of the fiber length, the worse the effect is enhanced. RRIM products in enhanced fiber content (mass fraction) is generally below 20%, for the special requirements of high-strength products to enhance the fiber content of up to 50%.
3. Epoxy RIM
Epoxy resin is the second thermosetting polyurethane RIM developed after another species. Two-component epoxy and polyurethane RIM RIM process roughly the same. Epoxy resin and curing agent ratio and process conditions in Table 2.
RIM products epoxy tensile strength and flexural modulus, low coefficient of linear expansion, and has excellent chemical resistance and high heat resistance (as compared with polyurethane and nylon). In order to improve the impact strength of epoxy resin can be added to the raw materials base with isocyanate, relative molecular mass of 4? 000 polyethylene glycol prepolymer.
In addition, to further improve the mechanical properties, but also adding a variety of reinforcing materials, such as various fiber, whisker powder, flakes, beads and other materials and long fibers, making RRIM products, their applications in the automotive industry very competitive.
4. Nylon 6 RIM
Nylon 6 RIM raw materials used include polyether polyols and a catalyst made from the prepolymer (A component) and caprolactam (B component). Processing, raw materials can first join caprolactam, the control temperature of 74 ~ 85 ℃, then add the catalyst, closed container, strong mixing of the catalyst dissolved in caprolactam, the mixture degassed under N2 15min. Caprolactam and then the prepolymer blend, temperature 74 ~ 85 ℃, stir well before degassing. Then under pressure, two liquid components through the mixer into the mold, curing. As occurred in the prepolymer and block copolymerization of caprolactam, which derived products, flexible, high impact strength.
Added reinforcement of nylon 6 RRIM products, higher rigidity, low coefficient of linear expansion. Nylon 6 RIM and RRIM products use a wide, mainly for the automotive industry, such as fenders, doors, hood and bumper cover.
5. Dicyclopentadiene (DCPD) RIM
DCPD RIM raw materials including DCPD, catalysts, activators, stabilizers, modifiers, fillers, antioxidants, elastomers, foam, fire retardants and nucleating agents.
In the DCPD RIM system, will generally be divided into various raw materials required by formula A, B two points, A component including DCPD, catalysts, stabilizers and other additives. B component including DCPD, activators, regulators and other additives.
Processing, the accurate measurement of A, B two points in the mixing head after mixing, was injected into the sealed mold, the mold rapid polymerization occurs, followed by curing. Need special attention, in the mold is not filled before the polymerization time modifier to control chemical reactions. After the mold is full, about 10s to complete the polymerization and molding. Products generally do not need to go through after the aging process.
6. Polyurea RIM
Polyurea RIM uses a mold with the material from the release agent within the system, forming by the end of amino polyether, amine chain extenders and isocyanate end groups of the prepolymer (MDI) reaction made polyurea. The process has many excellent features: As the amine and isocyanate reactivity, hence no catalyst; reactants into the mold cavity when the viscosity, while reducing the vortex filling, so little into the air, products scrap rate; material into the mold after 1 ~ 2s occurs within the gel, just to stay in the mold 20s; mold cavity when the material does not stick, use less restricted within the release agent system; prepared by adding glass fiber to enhance Polyurea RRIM products, the amine and isocyanate for the reaction between the no effect.
Polyurea generated throughout the reaction process does not require a catalyst, making the products in no residual catalyst, therefore polyurea RIM products do not degrade at high temperatures, product stability.
Terminal amino polyether diamine chain extenders and MDI's fast response. To control the reaction in the state, part of polyether polyols can be modified to the MDI prepolymer made a half, thereby reducing the speed of the reaction between the material, slowing the response speed of the gel material. Also, by adjusting the isocyanate group content travel divorced, can be obtained with different bending elasticity modulus polyurea RIM products. The Dow Chemical Company SPECTRIMTMHT series polyurea performance in Table 3.
7. Mat molding RIM
Will enhance the fiber mat piece, pre-placed in the mold, and then, two sub-hit by high-pressure low-viscosity liquid mixture and injected into the cavity. In the cavity, the mixed liquid impregnated fiber mat formed by the reaction products and film, this molding method is known as "Mat molding RIM (MM / RIM)". ARIMA × 1000 is the Ashland developed MM / RIM product, its performance is shown in Table 4.
8. Variable fiber reaction injection molding (VFRIM)
MM / RIM technology is the first fiber laid in the mold cavity, and then injected into the liquid resin. The disadvantage of this process is the need to pre-mat, so that complicated processes, increase costs. In addition, as required by hand shop mat, but also greatly increased the labor intensity. Based on this, and gave birth to a variable fiber reaction injection molding (Variable fiber injection reaction injecction molding, VFRIM).
This technology was developed by Krauss-Maffei in Germany and Italy Cannon-Technos in the 1990s development. The important feature of the first fiber roving into the shredding machine, cut into short fibers dispersed, then the short fibers mixed into the L-shaped head, the mixing with the resin, and finally the mixture into the mold for curing.
Now use technology products VFRIM a car door, cushion trays, bumper, sun visor, luggage tray and light truck box panels. Tables 5 and 6 are typical of low-density and high density VFRIM products and compare the performance of traditional R1M products. It can be seen, the use of technology to produce low-density products VFRIM performance and very traditional RIM products. The use of VFRIM technology to produce high-density product compared with RIM products, showed a better performance.
VFRIM one of the advantages of technology is that by adjusting the fiber chopper, you can control the fiber length, intensity and amount of fiber roving, fiber in the products to control the distribution. The second advantage is the significant cost reductions. Fiber roving cost than conventional SRIM technology for glass fiber mat 60% lower. By reducing the spread of glass fibers into the mold process, the cost is correspondingly reduced; in the injected resin / glass fiber mixture, due to precise control and reduce waste. These combined factors make the production costs, which is the main advantage of the technology.
VFRIM technologies are evolving, I believe the technology in the automotive parts industry will play an increasingly important role.
Table 2 epoxy formulations and process conditions
Table 4 ARIMA × 1000 performance
Table 6 high-density VFRIM products and traditional products of high density SRIM performance comparison
Table 5 Low-density VFRIM door panels and door panels of the traditional low-density performance comparison RIM
Table 3 Series performance polyurea SPECTRIMTMHT
Great information.keep blogging.hot runner mould manufacturers
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