polycarbonate PC mold making

PC injection mold is a type of mold, but what distinguishes it from other products is that PC injection molds are made of high-end products, because the surface technology is particularly good, and products that can be made of PC materials, They are usually high-gloss products or micro-displays.

Polycarbonate(PC) moulding material properties

Material main properties

• 1. Amorphous material, good thermal stability, wide molding temperature range, and poor fluidity. Hygroscopic, but sensitive to water, must be dried. The molding shrinkage is small, and melt cracking and stress concentration are easy to occur. Therefore, the molding conditions should be strictly controlled. The plastic parts must be annealed.
• 2. Plastic parts with high melting temperature and high viscosity, more than 200g, should use heating type extension nozzle.
• 3. Poor plastic fluidity. The mold pouring system is based on the principle of thick and short. Cold material wells should be set, the gate should be large, and the mold should be heated.
• 4. If the material temperature is too low, it will cause lack of material, the plastic parts are dull, if the material temperature is too high, it will overflow, and the plastic parts will foam. When the mold temperature is low, the shrinkage is small, the elongation is small, the impact strength is low, and the bending, compression and tensile strength are low. When the mold temperature exceeds 120 degrees, the plastic part cools slowly and is easy to deform.
• 5. The plastic wall should not be too thick and should be uniform to avoid sharp corners and gaps

Handling of PC raw plastics

1. PC has a large water absorption rate. It must be preheated and dried before processing. Pure PC is dried at 120 ° C. Modified PC is generally dried at 110 ° C for more than 4 hours. The drying time should not exceed 10 hours. Generally, the air-extrusion method can be used to judge whether the drying is sufficient.
2. The proportion of recycled materials can reach 20%. In some cases, 100% recycled materials can be used. The actual amount depends on the quality requirements of the product. Recycled materials cannot mix different masterbatches at the same time, otherwise the properties of the finished product will be seriously damaged.

Selection of injection molding machine of PC mould

PC Mould and gate design

1. The larger the gate, the better, so as to reduce the plastic caused by excessive shear.
2. The depth of the exhaust hole should be less than 0.03-0.06mm, and the flow channel should be as short and round as possible.
3. The demolding slope is generally about 30′-1.

Melt temperature

Injection speed

Back pressure

Residence time

Precautions