Defects and solutions of transparent plastic injection molding products

The defects are roughly as follows: 　　(i) Silver streaks: Due to the anisotropy of internal stress during mold filling and condensation, the stress generated in the vertical direction causes the resin to be oriented in the flow direction, and the refractive index is different from the non-flow orientation, resulting in flash streaks. When it expands, it may cause cracks in the product. In addition to paying attention to the injection molding process and mold (see table, it is best to anneal the product. For example, PC materials can be heated to above 160°C for 3 to 5 minutes, and then naturally cooled. 　　(ii) Bubbles: Mainly because the water vapor and other gases in the resin cannot be discharged (during the mold condensation process) or due to insufficient mold filling, the condensation surface condenses too quickly to form “vacuum bubbles”. The method to overcome it is shown in the table. 　　(iii) Poor surface gloss: Mainly due to the large roughness of the mold, on the other hand, the condensation is too early, so that the resin cannot copy the state of the mold surface. All of these make the surface produce tiny bumps and bumps, The product loses its luster. See the table for methods to overcome it.(IV) Chatter marks: refers to the dense ripples formed from the sprue as the center. The reason is that the melt viscosity is too high, the front end material has condensed in the cavity, and the later material breaks through the condensation surface, causing chatter marks on the surface. See the table for methods to overcome it.

(V) Whitish. Halo: Mainly caused by dust in the air falling into the raw materials or too much water content in the raw materials. See the table for methods to overcome it.(VI) White smoke. Black spots: Mainly caused by the decomposition or deterioration of the barrel resin due to local overheating of the plastic in the barrel. See the table for methods to overcome it. Table. In order to make it clear that the measures taken to overcome these deficiencies are explained, a table is listed for your reference. Table 4: Defects of transparent products and methods to overcome them: Methods to overcome\Defects Silver streaks Bubbles Poor surface gloss Chatter streaks Whitening, fog and halo White smoke, black spots Impurities or contamination in the resin raw materials Remove impurities and contamination Remove impurities and contamination Remove impurities and contamination Resin raw materials are dried Dry thoroughly Dry thoroughly Dry thoroughly Melt temperature Lower, control accurately to ensure plasticization and then lower Increase Increase, especially the nozzle Lower, control accurately Lower the material temperature as much as possible Injection pressure Increase Increase Increase Increase Increase Adjust appropriately and do not deteriorate Injection speed Increase Increase Increase Injection time Increase Increase Ensure pressure Production cycle Reduce Reduce material residence time in the barrel Back pressure Pressure adjustment appropriately Increase Screw speed Reduce Pouring system reasonable (size and layout) Wall thickness part Add gate Setting layout reasonable (size and layout), as short and thick as possible Mold temperature adjustment appropriately, slightly increase Increase Increase Increase Cooling time increase Increase Mold exhaust Vent hole is in the right position Vent hole is in the right position Add cold material well Improve Vent hole is in the right position Nozzle, runner, gate cannot be blocked Material flow smoothly, no blockage Material flow smoothly, no blockage Injection volume increase