Development of Macro Program for Improving Machining Characteristics of Logarithmic Spiral on CNC Machining Center

Abstract

It was observed that various curve-shaped components are regularly used in today’s manufacturing industries considering the design and quality requirements. A logarithmic spiral is a self-similar spiral curve that often appears in nature. Curve-shaped components machining on CNC machine is difficult due to nonavailability of appropriate preparatory function codes. However, various commercial software are useful for curved-shape machining. The cutter location points on the curved profile are obtained by using computer-aided design (CAD) software. The computer-aided manufacturing (CAM) software generates detailed preparatory codes automatically from X and Y coordinates of the cutter location points with the help of post processors. Cutter interpolates tool path linearly between two successive cutter location points of the segments. It results in deviation of the tool path from the actual curved profile to be machined. This deviation of the tool is dependent on curvature of the geometry as massive data are communicated between CAD software and CAM systems. To reduce this deviation, the number of cutter location points needs to be increased. It results in the increase of number of linear segments of the tool path. Single block in the part program is added with each line segment. Length of the part program as well as program memory size is increased. Parametric programming is attempted to machine that curved profile. The purpose of the present work is to machine the logarithmic spiral curve expressed by mathematical equation using parametric programming. Surfaces quality for the machined curve is measured and reported.