What do you mean, injection molding is not bad?

Insufficient injection molding, depression, fusion joint, material flow pattern, poor gloss, air holes, black spots, overflow, warping deformation, silver inscription, poor demoulding, clouds, rough punching, horseshoe shape, small central hole, large central hole, too thick substrate, too thin substrate, large birefringence, small birefringence, substrate fracture, runner fracture, radial stripes, recording groove, etc.

The reasons for the above defects are: mold temperature, punching knife and runner temperature, injection speed, injection pressure, holding pressure, holding time, transition point, clamping force, cooling time, barrel temperature, plasticizing time, plasticizing speed, back pressure, etc.

Defects of injection molding parts, their causes and solutions

■ Due to the existence of moisture, bubbles will be generated.

Reason: The drying degree of granular materials is not enough, which causes resin hydrolysis.

Treatment method: do a good job of heat preservation management of pre-drying hopper.

■ Vacuum bubble

Reason: The material flow in the thick wall freezes quickly to prevent shrinkage, and the mold filling is insufficient, resulting in internal vacuum bubbles. The mold temperature is not suitable. The barrel temperature is not suitable. Insufficient injection pressure and holding pressure.

This treatment method avoids the design of structures with uneven wall thickness. Correct the gate position so that the material can be injected vertically into the thick wall. Raise the mold temperature. Reduce the temperature of the barrel. Increase injection pressure and holding pressure.

■ Fusion marker

Reason: The temperature of the mould barrel is not suitable. Injection pressure is not suitable. The mold temperature will not be disturbed. There is no vent hole in the die groove.

Treatment method: increase the barrel temperature. Increase the injection pressure. Raise the mold temperature. Set ventilation holes.

■ dent

Cause: The cooling speed is slow (unreasonable wall thickness design), and the inner surface of thick wall shrinks to produce dents. Injection pressure is not enough. The injection is not enough. The mold temperature is too high or the cooling after injection is not enough. Insufficient pressure maintenance. The gate size is unreasonable. Avoid uneven wall thickness.

Treatment: increase the injection pressure. Increase the injection volume. If the mold temperature is reasonable, the cooling time should be extended. The boss is stalling. Enlarge the gate size, especially its thickness.