Processing Machinery
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POM product discoloration and scorch marks
Problem Phenomenon
Yellow and brown discolored areas or black scorch marks appear on the product surface, accompanied by a slight pungent odor, concentrated at the end of the material flow and at dead corners.
Cause Analysis
The resin decomposes and discolors at local overheating spots in the barrel and nozzle, or is carbonized after excessive residence time and then carried out; entrained air undergoing adiabatic compression also causes local resin overheating and decomposition.
Solution
①Lower the temperature of overheated parts and remove stagnant material; ②adjust the barrel temperature appropriately; ③select an injection machine with matching capacity to shorten residence; ④clean the nozzle and barrel dead corners.
Key Takeaway
Discoloration and scorch marks are direct visible signals of POM thermal decomposition; temperature management and stagnant material cleaning are equally important, and after scorch marks appear, the machine should be fully purged before continuing production.; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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