Molds & Tooling
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ABS dimensional instability
Problem Phenomenon
The dimensions of products from the same mold fluctuate between batches, out of tolerance without pattern, affecting precision assembly parts.
Cause Analysis
Unstable holding switchover point, cushion fluctuation, check ring wear and leakage, melt/mold temperature drift, and regrind ratio changes all cause shrinkage rate fluctuations, and then dimensional drift.
Solution
①Fix the holding switchover position and monitor the cushion; ②check the sealing of the check ring; ③stabilize the drying and regrind ratio; ④constant temperature water supply from the mold temperature controller; ⑤establish SPC dimensional monitoring.
Key Takeaway
For ABS dimensional drift, first check 'plasticizing and metering stability': the cushion and check ring are the primary suspects; dimensions are the result of process stability, fix the process variables and the dimensions will naturally be stable.
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