Using the Aspect Ratio of Surface Void-Volumes to Quantify Surface-Topography Directionality

摘要

Surface directionality can be quantified using a parameter called the volumetric aspect ratio, VAR. The VAR can also provide insight into the lubrication conditions at the die-workpiece interface. During lubricated upsetting at high and low speeds the directionality of surfaces with both rolling and transverse direction surface scratches was decreased. Low-speed upsetting resulted in the greatest disparity of the VAR between the TD and the RD surfaces. The RD surface exhibited higher frictional resistance than the TD surface during low-speed testing. This difference is expected to be the result of the difference in the VAR of the surface during testing. The RD and TD surfaces showed very little frictional differences during high-speed upsetting. This lack of difference is also reflected by the similarity of the VAR values from the RD and TD surfaces tested at higher speeds relative to the surfaces tested at low speed.