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

In molds and dies manufacturing, estimation of the machining time of tool p aths is a pre-requisite for planning the machining processes and balancing them. The machining time is computed by dividing the distance of the tool p ath 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 ma chining 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, a nd 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 effic ient regardless of feed-rates and path intervals and that the effects of ac celeration and deceleration are notably revealed at higher feed-rates. (C) 2001 Elsevier Science Ltd. All rights reserved.