Optical Coherence Scanning Measurement Limit Boundaries on Vertical Tooling Cavity Sidewalls
Side-viewing prisms and polarized optical coherence gating extend sidewall slope scanning limits beyond eighty-five degrees in deep tooling cavities.
Sinker Edm Roughness
Meaning
Arithmetic mean deviation of the surface profile created on a mold component through the process of electrical discharge machining with a shaped electrode. This texture is formed by thousands of tiny sparks that melt and vaporize the steel, leaving behind a series of overlapping craters. The resulting finish is non-directional, which assists in the release of plastic parts from the cavity compared to a ground or milled finish with directional grain.
Surface Topography
Density and depth of the craters depend on the peak current and pulse duration used during the final spark passes. The sinker edm roughness of a tool dictates the aesthetic appearance of the moulded part, providing a uniform matte look that hides sink marks or internal ribs.
Release Performance
Draft angles must be increased when a coarser texture is specified to prevent the plastic from gripping the cavity walls. If the surface is too rough, the part may drag or scuff during ejection, leading to scrap and increased cycle times.
Process Control
Consistent finishes are achieved by managing the wear of the graphite or copper electrode. As the electrode geometry degrades, the uniformity of the sinker edm roughness across the cavity floor varies, requiring the replacement of the tool or a finishing pass with a fresh electrode.