Transparent plastic parts have strict requirements on the surface quality of plastic products due to the high light transmittance, and they must not have any markings, pores or whitening. Haze, black spots, discoloration, poor gloss and other defects, so the entire injection molding process has strict or even special requirements for the design of raw materials, equipment, molds, and even products.

(1) Preparation and drying of raw materials
The moisture in the raw material, which will cause the raw material to deteriorate after heating, so it must be dried. When injection molding, dry hopper must be used for feeding. 
(2) Cleaning of the barrel, screw and accessories
In order to prevent the contamination of raw materials and the existence of old materials or impurities in the recesses of the screw and accessories (especially in the presence of resins with poor thermal stability).

(3) Problems that should be noted in mold design (including product design)
a) The wall thickness should be as uniform as possible, and the draft angle should be large enough;
b) Smooth transition to prevent sharp corners and sharp edges, especially PC products must not have gaps;
c) The gate runner should be as wide and thick as possible, and the gate position should be set according to the shrinking and condensation process, and the cold material well should be added if necessary;
d) The surface of the mold should be smooth and low in roughness (preferably less than 0.8);
e) The venting holes and grooves must be sufficient to venting the air and the gas in the melt in time;
f) Except for PET, the wall thickness should not be too thin, generally not less than 1mm.