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In the production process of the SMC sheet moulding compound, due to the production process, the number of different products will appear some deviations. To address this situation, our engineers, through an extended study of the glass fiber reinforced plastic molding process, summed up the following common molding process product problems and solutions.
Surface Porosity
The problem occurs for the following reasons.
1. The charging area is too large, and the surface air cannot be removed because the process is too short.
2. The shear edge is too large, there are dry fibers, and the starting viscosity of resin paste is high.
3. A pre-gelatinization zone on the part.
4. The SMC material is dry or soft.
The solutions to the problem are:
1. Reducing the feeding area by adding small pieces to the top of the large feeder.
2. Repair the shear edge to reduce the starting viscosity of resin paste.
3. Increase the impregnation zone work rolls and replace the glass fibers.
4. Lower the mold temperature and add inhibitors to the resin paste.
5. Wrap SMC material with impermeable film, and do not over-prepare material when molding.
Difficult to release products from the mold
The reasons for this problem are:
1. The mold temperature is too low.
2. Curing time is too short.
3. The rolls of material take too long to open the outer packaging.
4. Using new molds or molds that have not been used for a long time and have not been opened.
5. The surface of the mold is too rough.
The solutions to this problem are:
1. Increase the mold temperature.
2. Extended curing time.
3. Always keep rolls of material sealed before use.
4. Use of external release agents for the first few dies.
5. Surface polishing.
Dark brown or black color on unfilled areas
The reasons for this problem are:
The trapped air and styrene vapor are compressed to increase the temperature.
The solutions to this problem are:
1. Improve the feeding method to allow air to flow out with the material.
2. If brown spots appear in the blind holes, use a three-and-a-half die structure or exhaust with an ejector pin.
The surface of the product is dark
The reasons for this problem are:
1. Too much pressure;
2. The SMC plastic molding temperature is too low;
3. The mold surface is not ideal.
The solutions to this problem are:
1. Increase pressure;
2. Increase mold temperature;
3. Chrome plating of mold.
Surface Porosity
The problem occurs for the following reasons.
1. The charging area is too large, and the surface air cannot be removed because the process is too short.
2. The shear edge is too large, there are dry fibers, and the starting viscosity of resin paste is high.
3. A pre-gelatinization zone on the part.
4. The SMC material is dry or soft.
The solutions to the problem are:
1. Reducing the feeding area by adding small pieces to the top of the large feeder.
2. Repair the shear edge to reduce the starting viscosity of resin paste.
3. Increase the impregnation zone work rolls and replace the glass fibers.
4. Lower the mold temperature and add inhibitors to the resin paste.
5. Wrap SMC material with impermeable film, and do not over-prepare material when molding.
Difficult to release products from the mold
The reasons for this problem are:
1. The mold temperature is too low.
2. Curing time is too short.
3. The rolls of material take too long to open the outer packaging.
4. Using new molds or molds that have not been used for a long time and have not been opened.
5. The surface of the mold is too rough.
The solutions to this problem are:
1. Increase the mold temperature.
2. Extended curing time.
3. Always keep rolls of material sealed before use.
4. Use of external release agents for the first few dies.
5. Surface polishing.
Dark brown or black color on unfilled areas
The reasons for this problem are:
The trapped air and styrene vapor are compressed to increase the temperature.
The solutions to this problem are:
1. Improve the feeding method to allow air to flow out with the material.
2. If brown spots appear in the blind holes, use a three-and-a-half die structure or exhaust with an ejector pin.
The surface of the product is dark
The reasons for this problem are:
1. Too much pressure;
2. The SMC plastic molding temperature is too low;
3. The mold surface is not ideal.
The solutions to this problem are:
1. Increase pressure;
2. Increase mold temperature;
3. Chrome plating of mold.
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