Injection Molding
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ABS check ring wear causing alternating short shot/flash
Problem Phenomenon
Under the same process, short shots and flash of the product appear alternately, the single weight fluctuates greatly, and the cushion fluctuates large and small.
Cause Analysis
The check ring is worn or stuck, causing the melt to flow back during injection, and the actual shot volume is unstable; cushion fluctuation is the most intuitive manifestation, and metering instability causes short shots and flash to alternate.
Solution
①Continuously monitor the cushion fluctuation (e.g., 30 shots); ②disassemble and inspect the check ring wear and replace it; ③clean foreign matter at the screw head; ④stabilize the back pressure and speed; ⑤check the feeding stability.
Key Takeaway
For ABS alternating short shot and flash, suspect the check ring first: this is a typical fault signal of the metering system; only by stabilizing the cushion do the process parameters make sense, otherwise the more you adjust, the more chaotic it gets.
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