(1) What is discoloration (appearance)? Discoloration means that the color of the molded product is not consistent with the required color. Since plastic is a chemical substance, it gradually decomposes and deteriorates when it is heated to over the melting point. Discoloration is caused during this process. Fig. 1: Sample with Discoloration
What is pitting (appearance)? Pitting mainly refers to the dents produced on thick walls. Pitting is caused because the resin does not stick to the cavity surface. There are many reasons for the appearance of pitting, but the main reason is that the holding pressure is not high enough.
What are black spots?(appearance)? Black spot refer to the black Speck or streak on a molded product. The black spots appearing on the surface of a molded product are the black spot. For some reason, its composition is estimated to be a charred resin or a carbonized resin.
(1) What Is Burn Mark? (Appearance) Burn Mark refers to the blackened edge that is caused on the surface of a molded product during the injection molding process. Fig. 1: Burn Mark on a Sample Handle (* Sample size is approx. 10cm)
What Is Welding Line? (Appearance) The weld line appears where the resin flows meet. As shown in the figures below, weld lines will definitely appear in the part with opening. The Causes of Welding Lines (2-1) Low Resin Temperature...