Investigation on the effect of machining parameters on surface roughness during turning of kenaf fiber-reinforced composite using non-contact vision method

Machinability studies on natural fiber-reinforced composites (NFRCs) in the past have been limited mainly to drilling. There is limited work published on the effects of machining parameters on the surface finish quality during turning of NFRCs. The objective of this research is to investigate the effects of spindle speed and feed rate on the surface finish quality of kenaf fiber-reinforced composites during turning. A non-contact machine vision method was used to determine the surface roughness parameters. The image of the edge profile of each composite specimen after machining was captured using a high-resolution digital camera with the aid of backlighting. The edge profiles were extracted to sub-pixel accuracy from the digital images. Six roughness parameters were determined from each extracted profile and plotted against feed rate. The results show that high spindle speed generally produced poor quality surface finish at all feed rates tested. This was mainly due to the centrifugal forces caused by the high rotational speed of the workpiece, which tends to stretch out the loose uncut fibers radially. Different depths of cut were found to produce different surface roughness depending on whether the cutting tool passes fully through, partially, or in-between the fiber bundles. Better surface finish was obtained at low spindle speeds and low feed rates when the tool passes mainly in-between the fiber bundles.