Tooling Surface Polish Impact on First Article Inspection Accuracy
Uncalibrated optical scans on mirror-polished plastic introduce up to fifteen micrometers of false elevations, ruining First Article Inspection accuracy.
Tool Steel Removal
Meaning
Subtractive metal machining alters mold cavity dimensions to correct part shrinkage discrepancies or modify plastic component geometry. Performing tool steel removal on core pins or cavity block walls increases local wall thickness in injection moulded plastic parts. Precision CNC milling or spark erosion remove hard tool steel while maintaining tight dimensional tolerances across shut-off surfaces.
The process stops at structural wall limits where excessive metal removal weakens cavity strength under injection clamping forces.
Cavity Modification
Dimensional tuning of injection tooling relies on controlled cutting operations after initial sampling trials reveals plastic shrinkage variations. Targeted tool steel removal from core faces compensates for unexpected resin sink marks or flexural warpage in production parts. Cutting back steel increases local wall thickness, improving melt flow into restrictive ribs during filling.
Precision EDM sinker passes finish complex deep pockets that conventional end mills cannot reach.
Steel Hardness
Pre-hardened P20 steel allows direct machining, whereas fully hardened H13 tool steel requires carbide tooling or spark erosion. Heavy machining steps during tool steel removal induce localized residual stresses, requiring stress relief tempering to prevent mold cracking under thermal cycling.
Quality Verification
Verifying metal removal depths using CMM measurement prevents over-machining mold shut-off faces. Proper steel removal restores part dimensions to CAD specifications without causing cavity flash.