The present work is a study of the effect of specimen shape for different specimen types and test duration times on the erosion process. Erosion changes the surface geometry of the parts, components of machines that will affect the performance and efficiency of the parts to be lower than design and may cause failure. Experimental test was carried out using a specially designed test-rig to investigate the effect of specimen shape for Stainless steel 304, and steel 37 coated with Ni-Cr thin film (38 m) in material erosion. The test-rig is based on Specimens rotate in slurry pot, sand in water, with a controlled speed to simulate a required relative velocity between slurry and specimens. Sand particles concentration with water was of 40 wt. %. The sand particle maximum size was 550 µm.