Injection Mould Cavity Surface Roughness Measurement Using Silicon Replicas
Indirect silicone replica metrology resolves deep mould cavity roughness parameters non-destructively within five percent variance of direct steel scans.
Stylus Profilometer
Meaning
A physical probe that moves across a surface to map its height variations provides a direct measurement of roughness and waviness. The stylus profilometer uses a diamond tip to track the peaks and valleys of a mould cavity or a finished plastic part. This contact method is a standard for verifying tool finishes and ensuring they meet the required specifications.
It translates the mechanical movement of the tip into an electronic signal that generates a two dimensional or three dimensional profile of the texture.
Measurement Accuracy
Accuracy of the measurement depends on the radius of the diamond tip and the force applied to the surface. A very sharp tip can fall into smaller crevices but might also scratch softer polymers during the scan. If the stylus profilometer is set with too much downforce, it can deform the features it is trying to measure, leading to an inaccurate representation of the topography.
Modern systems use low force sensors to mitigate this risk while maintaining high spatial resolution.
Calculation Method
Data from these scans are typically used to calculate standard parameters like Ra or Rz for quality control reports. These values allow a buyer to compare the finish of a part from one supplier against the master specification.
Maintenance Routine
Measuring the steel surface directly helps identify the gradual wear caused by glass fibers or mineral fillers in the resin. Because the stylus profilometer can reach into deep cavities, it is an essential tool for auditing the health of a mould over time. If the measured roughness exceeds the limit, the tool is pulled for polishing or re-texturing to prevent a drop in part quality.