Increasing thin-walled workpiece stiffness to improve its surface roughness in the face milling process.

Surface roughness is one of the important characteristics of the workpiece made by machining process. In addition to the machining or cutting parameters, the stiffness of the workpiece in the machining affects its surface roughness. The surface roughness of the workpiece will get better as the stiffness of the workpiece increases. For workpieces that have a large length to thickness ratio, increasing the stiffness of the workpiece becomes an important issue to improve its surface roughness. The cutting test was carried out on the gearbox housing model (g-h model) which was represented as a thin-walled workpiece. Mild steel was chosen as material for the g-h model. Taking into account the shape of the thin-walled workpiece and the orientation of the face milling tool on the workpiece wall, granular stiffener is used to increase the stiffness of the workpiece. Although granular stiffener may not always be used as good stiffeners because of its several constraints, for face milling process of the g-h model the choice of this stiffener is appropriate. Preliminary measurements of the average vibration amplitude with experimental modal analysis on the tool spindle and g-h model in time domain using accelerometer to measure the vibration response have given results of 10 ms−2 and 400 ms−2 for the vibration amplitude. The magnitude of the average vibration amplitude of the g-h model of this initial measurements was the reason for why its stiffness must be increased. The addition of a stiffener to the g-h model (workpiece) has reduced the vibration amplitude of the workpiece from 2892 ms−2 to 393.04 ms−2. In the cutting test with 1.2 mm depth of cut, the addition of stiffener on the g-h model has improved the surface roughness from 1.8 μm to 0.92 μm. [ABSTRACT FROM AUTHOR]