An Optimization process of Automatic Finishing surface treatment Al 7075 by a Single Roller Burnishing Tool

This research designed and developed a single-roller burnishing tool for automatic finishing surface of 7075 aluminum alloy (Al 7075). The conventional finishing process for such materials requires complex processes such as turning, grinding, and polishing. In addition, the turning process cannot be achieved a surface finish with a low roughness. Therefore, the purpose of this research aims to design and fabricate a single-roller burnishing tool that can be installed on a CNC lathe.  In addition, the research will study the fundamental mechanisms of surface finishing improvement using a single-roller burnishing tool on Al 7075 and study the parameters that affect the surface quality of Al7075 by combining two automatic processes. This process includes turning and roller Burnishing, which will reduce the complex steps in surface finishing. In the experiment, the following parameters were used in the roller burnishing process: three levels of constant spring force 150, 300, and 450 Newtons, feed rate 0.05, 0.1, and 0.15 mm/rev and rotational speed 600 and 1,200 rpm. The results of the experiment showed that the feed rate was the main factor that affected the surface roughness of the workpiece with a statistical significance of 95%. The best feed rate was 0.05 mm/rev, which resulted in a surface roughness of 0.078 µmRa. The surface roughness after the turning process was 0.371 µmRa, which means the surface roughness was reduced about 4-5 times. In addition, the hardness of Al 7075 after roller burnishing increased by 34%. This shows that the process not only improves the surface roughness quality but also increases the residual stress on the surface of the workpiece.