A METHOD FOR ASSESSING THE QUALITY OF POWDER MATERIALS FOR 3D PRINTING BASED ON POLYAMIDE-12

Abstract

Morphological parameters of digital images of the materials used in powder 3D-printers are studied. Digital images of polymer samples were obtained in transmitted light using an optical microscope equipped with a digital ocular camera. Morphological analysis of images is carried out using the program ImageJ 1.45s. Statistical and correlation analysis of primary and secondary powders for layer-by-layer laser sintering based on polyamide-12 was carried out using Statistica 10 software package. The fact of agglomeration of coarse particles in a secondary powder is established, which leads to a change in the fractional composition and is one of the reasons for violation of heat transfer upon laser sintering during printing. Violation of the fractional composition can greatly change conditions of heat exchange in the laser focus zone and affect the quality of the finished products. It is shown that data on the area of the projection of the particles, their perimeter and Feret’s diameter obey the normal distribution law. The area of the projection of the powder grains is proposed to be used as an analytical signal, whereas the value of Pearson’s criterion greater than the minimum and corresponding to the degradation of the powder mixture with an unacceptable probability of production rejects — as a criterion of the suitability of the working mixture. Analysis based on the calculation of the correlation coefficient takes no more than 30 min and can be recommended as a rapid procedure for controlling the quality of a mixture of powders for printing.