Quantifying the influence of local porosity on the colour differences of dyed laser sintered polyamide-12 with X-ray CT

Aesthetic quality requirements for polymer laser sintered parts are becoming stricter to meet the high requirements of end-use applications. For laser sintered parts, several post-processing steps exist to improve the appearance of the parts, including sandblasting, tumbling or colouring. However, local changes in the porosity can influence the absorption of the colour dye and generate undesired colour differences. Test samples with altered build orientations are produced and post-processed by tumbling and colour dyeing. X-ray computed tomography is used to quantify the open and sub-surface porosity of the samples. The colour of the test samples is measured with an RGB colour camera. Device-dependent RGB values are converted to device-independent colour spaces (CIEXYZ and CIELAB), using a target-based colour characterization. Local ΔE* colour differences are calculated and aligned with 2D porosity maps of the open and sub-surface porosity. A strong correlation between the open pore volume and colour differences on the samples was observed.

ISBN:978-1-9989991-0-1

Jaar van publicatie:2021