Machining efficiency comparison direction-parallel tool path with contour-parallel tool path

In molds and dies manufacturing, estimation of the machining time of tool paths is a pre-requisite for planning the machining processes and balancing them. The machining time is computed by dividing the distance of the tool path by its feed-rate. This theoretical machining time always underestimates the actual time, because it does not take into account the effects of the acceleration and deceleration of the CNC machines. This paper proposes a machining time model that considers the acceleration and deceleration of the CNC machines. Using the proposed model, we compare the machining efficiency of the tool paths currently employed in molds and dies manufacturing-three types of direction-parallel tool paths (one-way path, pure-zig-zag path, and smooth-zig-zag path) and contour-parallel tool path. The results of the comparison simulation reveal that the smooth-zig-zag path is the most efficient regardless of feed-rates and path intervals and that the effects of acceleration and deceleration are notably revealed at higher feed-rates. (C) 2001 Elsevier Science Ltd. All rights reserved.