What is PC mold?

PC mold is a tool used to manufacture plastic products. It is made according to the shape and size of the desired product, by injection molding melted plastic in a mold, so that it is cooled and cured. PC mold plays an important role in industrial production, it can efficiently produce large quantities of plastic products, such as mobile phone cases, computer shells and so on. The production process of PC mold needs to go through design, processing, debugging and other links to ensure that the quality and accuracy of the mold meet the requirements of the product. And we Guangzhou otem Engineering Plastics Co., Ltd. has more than 20 years of PC products and PC mold processing experience, with professional production equipment and professional design and production team, can provide you with satisfactory product service.

PC injection molding processing conditions

1. Barrel temperature

The temperature of the barrel has a great influence on the quality of plastic products, and the low temperature of the material will cause the lack of material, the surface matt and silver wire; When the material temperature is high, it is easy to produce overflow and bubble

And discoloration. General cylinder temperature control at 230~310¡æ. For thin-walled products, the barrel temperature should be large; Small values are desirable for thick wall products.

2. Mold temperature

Under normal circumstances, the internal stress in the plastic parts is roughly proportional to the difference between the mold temperature and the material temperature during cooling, so the mold temperature is required to be higher, the mold temperature can be controlled at 80-120 ¡ã C, the thin-walled plastic products are suitable for 80~100C, and the thick-walled plastic products are suitable for 100~120 ¡ã C. If the mold temperature exceeds 120 ¡ã C, the plastic parts are slow to cool, easy to stick the mold, difficult to release, easy to warp, and the molding cycle is long.

3. Injection pressure

The viscosity of PC melt is high, so it requires a large molding pressure. When using a screw injection molding machine, the injection pressure is generally 70 to 140MPa, while the plunger injection molding machine is 100 to 160MPa. It can be determined according to the different conditions of raw materials, plastic products, molds and injection molding machines.

PC processing need to pay attention to matters

1, pay attention to dry treatment

Generally speaking, the hydrophilicity of PC is relatively large, so the PC board needs to be preheated and dried before processing, and the drying temperature and time should be controlled during the processing process, and the empty extrusion method is generally used to determine whether the drying is appropriate.

2. Mold making and gate design should be suitable

PC board processing is the main material of PC material, want to process into their own mind of graphics and plates, need to make molds and suitable gate design. In general, the larger the gate, the better to reduce the defects caused by excessive cutting of the plastic.

3, control the melting temperature and injection speed

In the process of PC board processing, the control of melt temperature is also relatively strict, because the modified materials and low molecular materials are different, so the control of melt temperature is also high and low. In addition, the PC board processing process should also control the speed of injection, especially for the faster injection molding, the need to use the switch key for speed control.

4, back pressure and retention time should be reasonable

In the process of PC board processing, the back pressure should be controlled, especially in the case of no color pattern and red, the back pressure should be properly reduced. And the PC board processing process is not easy to stay at high temperature for too long, otherwise it may affect the quality of materials and finished products.

PC processing often appear problems and solutions

1. Injection molding processing silver wire problem

Poor silver wire is the most common problem of PC materials, silver wire is also known as silver pattern, splash, material flower, etc., is the phenomenon of silvery white silk stripes along the flow direction on the surface of the product.

Solution: First check whether the material is dry enough, and then adjust the injection molding process to improve the silver wire defect after confirming that the material is dry enough. At the same time, poor injection silver wire is also related to mold exhaust.

2. Injection molding process flow mark problem

Flow marks are generated when the material is injected, the reason is that the material has poor fluidity, flow marks are different from silver marks, it is not caused by moisture or material decomposition, and the appearance is not the same.

Solution: It can be avoided by increasing the temperature of the material to improve the fluidity, and it can also be solved by appropriately increasing the mold problem to increase the fluidity of the material in the mold and reducing the injection speed.

3. Shrinkage holes and dents

Shrinkage hole is caused by insufficient material filling in the mold cavity.

Solution: Appropriately increase the mold temperature and material temperature to improve the flow of materials, extend the injection pressure holding time, increase the injection pressure, increase the injection speed to improve the mold filling, you can also increase the size of the gate, heating the gate runner to reduce and eliminate the shrinkage of products;

Dents are caused by improper material temperature and improper product design, when the material temperature is too low, not only shrinkage holes will occur, but also dents will occur, the material temperature is too high, the mold temperature is too high, which will make the molten material shrink too much when cooling, resulting in dents.

Solution: Adopt appropriate processing problems, improve injection speed and measures.

4. The warping deformation problem of injection molding

The warping deformation of injection molding parts is due to the unreasonable design of parts, improper gate position and unreasonable injection molding processing conditions, resulting in internal stress, uneven or excessive shrinkage, mold temperature is too high or mold temperature is not uniform, causing the release of the mucous membrane of the parts, or uneven cooling, the same will produce warping deformation;

Solution: Lengthen the injection molding cycle, reduce the injection temperature, adjust the injection pressure and injection speed, slow down the ejection speed, increase the ejection area, and maintain the ejection force balance; The warping deformation can be reduced by increasing the wall thickness, reinforcing bars and rounding corners.

5. Markings in injection molding

It is usually caused by the "melt rupture" caused by the expansion of molten material into the mold cavity during high-speed injection.

Solution: Increase the material temperature, increase the nozzle temperature, slow down the injection speed to reduce the appearance of markings;

Mold: increase mold temperature, add overflow groove, increase gate size, modify gate shape.

6. Pitting problem in injection molding

Solution: poor dispersion, add dispersant or oil, increase the temperature, add back pressure. Pay attention to mold problems. Try something else. Whether the baking temperature time is sufficient. Mold temperature adjustment.

7. The problem of "peeling" of injection molding products

There is a great relationship between the peeling problem of plastic products and the fluid rupture caused by high shear force. At low shear stress or rate, the small disturbance caused by various factors is inhibited by the melt. However, under high shear stress or velocity, the disturbance in the fluid is difficult to restrain and develops into unstable flow. When a critical shear force is reached, the rupture of the fluid will be caused.

Solution: Appropriate compatibilizers must be added in the modification process to improve its compatibility. Of course, because the bad peeling caused by the mixture is the first step we need to eliminate;