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Why Have Burn Marks in Injection Molding?
Original: Orignal | Author: DGMF Mold Clamps | Publish Time: 2021-11-27 | 2553 Views | Share:
When it comes to molding defects, burn marks in injection molding are some of the most common. Why have burn marks in injection molding?


If the melt temperature is too high, likely to cause decomposition of coking melt, resulting in spots plastic surface to produce a paste. Screw rotation general injection molding machine should be less than 90r / min, back pressure is less than 2mpa, to avoid excess friction heat generated cartridge.


If the molding process due to the rotation time of the screw is too long to return excess friction heat is generated, by appropriately increasing the screw speed, extending cycle times, reducing the screw back pressure, improving feed barrel section temperatures, and use of raw materials of poor lubricity methods to be overcome.


Injection, the melt in the screw groove and the check ring at reflux much resin retention, can lead to reduced melt polymerization decomposition. In this regard, the higher viscosity resin should be used, due to lower injection pressure, with a large aspect ratio change of the injection molding machine.


Commonly used injection molding machines are relatively easy to check ring cause retention decomposed discoloration, discoloration decomposition after melting material into the cavity, i.e., the focus formation of brown or black. In this regard, the system should be cleaned regularly to screw the nozzle as a center.