Evaluating the Surface Finish of A356-T6 Cast Parts from Additively Manufactured Sand Molds

Binder jetting of sand allows for the design and rapid fabrication of complex molds and cores. The surface finish of the printed molds and cores can be transferred to the cast part. A benchmark casting was designed to compare the surface roughness and surface features of several angles on the cast part. The benchmark casting contained surfaces with angles from 5° to 30° at 5° intervals. Benchmark castings from coated and uncoated mold surfaces were evaluated. Angles from 5° to 20° produced a prominent stair step feature. A Keyence microscope was used to measure the arithmetic mean roughness (Ra) and root mean square surface roughness (Rq) of the part surfaces. These measurements are compared to a more conventional contact profilometer. The suitability of Ra and Rq for characterizing stair step features will be discussed.