Influence of Tool Path Strategies and Pocket Geometry on Surface Roughness in Pocket Milling

This paper discusses the effect of tool path strategies and pocket geometry to surface roughness due to pocket milling process. The machining processes have been performed on mould steel DF2 using carbide insert end mill as the cutting tool. The cutting parameters for this experiment were kept constant while the variables were cutting tool, path strategies and pocket geometries at three levels each. The effectiveness of different tool path strategy and different pocket geometry is evaluated in terms of measured surface roughness (Ra) of the workpiece. The grade of a pocket is directly proportional with its surface roughness. The lowest surface roughness measurement was produced by pocket geometry B with parallel spiral cutting tool path strategy.

Image Morphology-Based Path Generation for High-Speed Pocketing

Pocket milling has long been a popular means for machining pocket features in structural parts and skins in the aviation industry. Recent advanced milling technologies pose new challenges for pocket milling path which existing contour-parallel path generation schemes cannot overcome. For high-speed machining, pocket milling path is desired to be smooth and with no tool retractions during the process, while the path stepover should be kept within a prescribed range to achieve relatively constant cutting load. These geometric constraints are also vital in the application of aircraft skin mirror milling in order to guarantee a correct and consistent thickness signal reception for real-time adjustment of the process. Traditional path optimization based on local modification can only meet a few of these constraints while others are being violated. Therefore, we propose a novel contour-parallel path generation scheme that respects all these process constraints by utilizing the idea of image morphology. The two-step scheme first generates an initial path by propagating from the rectified medial curve of the pocket shape. The initial path is then treated as a binary image being iteratively deformed and projected back into the pocket region via quadratic optimization. Experimental results show that our developed scheme can generate a smooth, tool retraction free and stepover-guaranteed path for various shapes of pocket.

Influence of Cutting Parameters and Tool Path Strategies on Surface Roughness in Pocket Milling of UNS A96082 Alloy

CNC Pocket Milling is the commonly employed machining process in molding, aircraft building, and shipbuilding industries. Surface integrity is one of the main quality parameters considered to accept the component. In the present work, an attempt is made to optimize the cutting factors in pocket milling of UNS A96082 using two different tool path strategies to get a better surface finish. Speed, Feed and Step over are considered as influencing parameters in the present study for measuring surface roughness. Taguchi experimental design method is employed to conduct experiments and to optimize the cutting parameters. It is observed that the results obtained from confirmation experiments also show nearer value for predicted surface roughness