Client Problem;A packaging manufacturer had sealing issues on flip-top caps. The main drift was found on the thread pitch diameter and sealing land of the core pins, with variation reaching ±0.03 mm, measured by CMM across batch samples. This affected thread engagement and sealing contact, causing leakage during validation tests.
Root Cause
The issue came from instability in the previous supplier’s process, including:
worn grinding tools
thermal distortion during machining
residual stress after heat treatment
poor control of thread-related CTQ geometry
These factors caused batch-to-batch drift and uneven sealing performance.
What We Changed
We rebuilt the machining route around the CTQ thread features:
used Hardinge CNC lathes with hydrostatic bearings for more stable turning
applied Böhler steel with controlled OEM heat treatment
reduced heat input during machining to improve dimensional consistency
verified CTQ geometry with Zeiss CMM
checked geometry against assembly and leak test results
A medical device manufacturer had dimensional instability in the cores of a 32-cavity syringe mold. Cavity-to-cavity variation reached ±0.015 mm, which caused flash during molding and affected consistency.
After review, we found that the previous supplier’s roughing strategy created unstable cutting load in the deep rib areas, leading to tool deflection and uneven stock before finishing.
We adjusted the process to improve stability on 58 HRC hardened cores.
