Optical absorptance of the plastic material is a critical parameter in the quality of weld seam during the laser plastic welding process, and frequent measurements of this value are required because material properties of the plastics can fluctuate gr...
Optical absorptance of the plastic material is a critical parameter in the quality of weld seam during the laser plastic welding process, and frequent measurements of this value are required because material properties of the plastics can fluctuate greatly due to the change of the processing parameters such as compound mix and injection molding process variables. Absorptance is usually estimated indirectly by measuring the transmittance and reflectance of the material. Accurate measurement devices based on several principles, spectroscopic apparatus, integrating sphere, calorimetry method, for instance, have been developed and some are commercially available in the market. But these are not adequate for the regular use in the production field. In this work, portable equipment is developed for measuring absorptance with reasonable accuracy, convenience and angle dependent measuring capability. Measuring principle and instrumentation are described, and measurement results of PMMA and ABS plastic materials are presented.