No abstract

In this study an experimental investigation of effects of cutting parameters on surface roughness during end milling of aluminium 6061 under dry condition and minimum quantity lubrication (MQL) condition were carried out. Spindle speed (N), feed rate (f), axial depth of cut (a) and radial depth of cut (r) were cutting parameters chosen as input variables in the investigation of the surface roughness quality. The experimental design adopted for this study was the central composite design (CCD) of response surface methodology. Thirty samples were run in a CNC milling machine for each condition and the surface roughness measured using Mitutoyo surface tester. A comparison showing the effects of cutting parameters on the surface roughness for dry and MQL conditions in end-milling of aluminium were evaluated. Surface roughness values for MQL condition were lower with up to 20% reduction when compared to dry conditions. MQL cutting condition was found to be better and more reliable because it is environmentally friendly and gives better surface finish. With the obtained optimum input parameters for surface roughness, production operations will be enhanced.

Pocketing with zigzag toolpath (which maintains near to continuous tool-workpiece contact) that is continuously optimized with limiting pairs of axial and radial depths is investigated in this work. Analysis led to a set of 16 conditional expressions eligible for description of pocketing time. An eligible expression becomes effective when all associated conditions are simultaneously met while the rest of the eligible expressions remain dormant until dimensions of pocket and tool favours another. Similar analysis has been carried out in other works for one-way toolpath which permits idle return passes and thus expected to incur delay. Comparison of zigzag and one-way toolpaths shows that the former always hastens pocketing operation because it better utilizes the stability limit of the system by maintaining continuously optimized to and fro passes. Numerical studies gives that zigzag toolpath can even half pocketing time of one-way toolpath for some choice of limiting process parameters. Similar to the conclusion that has been drawn for one-way toolpath in an earlier work it is seen that utilizing the coordinate of maximum limiting material removal rate (MRR lim ) for both down-and up-milling in a scheme of zigzag pocketing will not necessarily provide the minimum time because of geometrical constraints.