Surface Anisotropy on 3D Printed Parts

Abstract

It is well known that the surface quality obtained in additive manufacturing processes is highly variable. There are several reasons for this, of which the most prominent is the staircase effect, which results from the fact that 3D printing can be actually considered as a 2.5 machining process, as we build the part layer by layer. However, this staircase effect can be very different on surfaces that are arranged in different ways. By measuring the values that characterise the surfaces (Ra, Rz), however, we can observe that they are direction dependent, i.e. it does not matter how we measure them. This phenomenon is called surface anisotropy. It is clear that the surface roughness also has an effect on the tribological behaviour. In the case of a component where it is in contact with another component and relative displacement occurs between them, frictional properties may play a prominent role, which may thus also become direction dependent. Surface roughness also has a clear effect on fatigue properties. Consequently, for parts undergoing periodic dynamic stresses, it may be important to choose the right manufacturing orientation. The present study aims to demonstrate the extent of variation in surface roughness on different surfaces of a part produced by FDM. For this purpose, surface quality factors are investigated and evaluated on a self-designed model produced with given manufacturing parameters.