Effects of burnishing parameters on the quality and microhardness of flat die surfaces

Abstract

Abstract In this study, the burnishing process is recommended as finishing operation of flat die surfaces for improving not only surface quality but also mechanical properties of milled die surfaces. This technique can be applied after milling operations in CNC milling centers with a single fastening that increases the accuracy of the die geometry. To determine both the usability of the process on flat die surfaces and the influence of process parameters, a simple burnishing tool with a fixed deformation element was designed and constructed. The CNC milling center was used for burnishing operations. The burnishing process was employed using a constant spindle speed on a flat surface. Burnishing feed rate, stepover, penetration depth, the number of passes, burnishing direction and coolant were chosen as process parameters. First, optimum parameters were stated, then macro and microstructure of the burnished surfaces were examined, and roughness and hardness measurements of surfaces were carried out. Results show that burnishing increased the surface quality and microhardness of flat milled surface. The penetration depth has the maximum and stepover has the minimum effect on surface quality. The coolant has the highest effect on microhardness. The burnishing direction has a significant effect on both microhardness and surface quality. It can be briefly stated that burnishing is an economic and feasible surface treatment process for finishing operations of die surfaces.