Plastic parts produced bubble causes and how to exclude:
  一.defect feature, plastic bubble is the main performance: in the vacuum holes plastic produce internal parts, also called vacuum bubble.
  二. The causes of defects and the elimination method: plastic parts can produce bubbles because of the melt in the solidification process, because the cooling speed and different, often is first cooled and solidified layer, while the inside is still hot melt state, and once the center cooling contraction, as the outer layer has been cured, then in the plastic parts will produce the vacuum cavity and the formation of bubbles. The concrete analysis is as follows: 1 of injection mould, if adopting the gate, the plastic pieces after packing, the cavity of the gate in front of the high pressure ratio, melt so straight at the gate is not curable, will melt flow, make plastic parts produced bubble, therefore, should avoid using the straight gate; if the gate area is too small, or is not the correct location, easy to cause the bubble, therefore, to adjust the gate area and position; if the gate position not located at the wall thickness, are prone to bubbles, in this regard, the gate should be located at the posterior wall of plastic parts. 2 injection molding process, the mold temperature is low, the melt into the mold, plastic outer lead cooled and solidified, and the center part of the subsequent contraction is due to shrinkage and produce bubbles, this should raise the mold temperature, melt temperature is too high; if, in plastic cooling curing will produce excessive shrinkage bubble, therefore, should reduce the melt temperature; if the pressure is not enough, which flowed back into the cavity of the melt, resulting in bubbles, this should increase the holding pressure; if injection time too short, melt into the cavity of the less dense, easy to excessive contraction caused by the bubble, therefore, should extend injection time. 3 pieces of plastic, if the wall thickness over wide, easy to generate bubbles, therefore, should become plastic design process, so that uniform thickness; if the plastic parts with thick section, this is easy to generate bubbles, therefore, should be modified the structure of plastic parts size. Four. Some resin shrinkage rate is high, the resin appeared bubble opportunities, therefore, should try to use small shrinkage of resin regeneration; if adding too much, melt shrinkage rate increase, easy to form a bubble, therefore, should be appropriate to reduce the amount of recycled material.