Novel testing device and routine to characterise the spreadability of powders for powder bed fusion processes – a problem-oriented approach
Published in Powder Metallurgy, 2022
Marco Mitterlehner, Herbert Danninger, Christian Gierl–Mayer, Johannes Frank, Wolfgang Tomischko, Harald Gschiel
A is the actual surface area, which is calculated by triangulating the surface as shown in Figure 13. For this, both the distance between the pixels in x- and y-direction, which equals the length of a pixel in the corresponding direction (lpx, x, lpx, y), and the height of the pixels (z) are used (seen in Figure 13 on the left). To calculate the lengths as well as the area of the triangles, the Pythagorean theorem as well as Heron’s formula is used. There is a small difference in the calculated area depending on how it is triangulated (seen in Figure 13 on the right). This difference was therefore evaluated, but it is not significant in the end and can therefore be neglected. Here it applies that the higher the area is, the rougher the surface is.