英语翻译
Recent studies show that of the amount of time an average part spent in a shop,only a fraction of that time was actually spent in the machining process.Let us assume that a part spent 50 hours from the time it arrived at a plant as a rough casting or bar stock to the time it was a finished product.During this time,it would be on the machine for only 2.5 hours and e cut for only 0.75 hour.The rest of the time would be spent on waiting,moving,setting up,loading,unloading,inspecting the part,setting speeds and feeds,and changing cutting tools.
NC reduces the amount of non-chip-producing time by selecting speeds and feeds,making rapid moves between surfaces to be cut,using automatic fixtures,automatic tool changing,controlling the coolant,in-process gauging,and loading and unloading the part.These factors,plus the fact that it is no longer necessary to train machine operators,have resulted in considerable savings throughout the entire manufacturing process and caused tremendous growth in the use of NC