【正文】 . Its magnitude depend on the accuracy of manufacture, quality, measure of the punching part, thickness of panel, magnitude of gap and degree of homogeneity. The accuracy of manufacture depend on the manufacture process. For the 1 mm thicked pound punching part made in medium steel, the experimental result and productive practice all prove that the burr of dies which produced by spark cutting are higher 25%~~30% than produced by grinder ,NC or CNC. The reason is that not only the latter have more exact machining accuracy but also the value of roughness Ra is less one order than the formmer, it can be reached . Therefore, the die’s initial blanked accuracy depends on the accuracy of manufacture, quality and so on. The normal error of the punch die is the practicable error when the fist cutter grinding and the last cutter grinding before the die produce the last qualified product. As the increase of cutter grinding, caused the measure the nature wear of the dies are gradual increasing, the error of punching part increase also, so the parts are blew proof. And the die will be unused. The hole on the part and inner because the measure of wear will be small and small gradually, and its outside form will be lager in the same reason. Therefore, the hole and inner form in the part will be made mould according to oneway positive deviation or nearly equal to the limit max measure. In like manner, the punching part’s appearance will be made mould according to oneway negative deviation or nearly equal to limit mini measure. For this will be broaden the normal error, and the cutter grinding times will be increased, the life will be long. The limit error in punching parts are the max dimension error which practicable allowed in the parts with limit error. This kind of parts usually are the last qualified products before the die discard.For the all classes of dies, if we analyse the fluctuate, tendency of increase and decrease and law which appeared in the die’s whole life, we will find that the master of the error are changeless。 ~ 177。這是因?yàn)楹笳卟粌H加工精度高，而且加工面粗糙度Ra值要比前者小一個數(shù)量級。沖模沖件的固定誤差取決于以下各要素：（1）沖件的材料種類、結(jié)構(gòu)（形狀）尺寸及料厚沖裁間隙的大小及其均勻度對沖裁件的尺寸精度有決定性的影響。意大利Corrada公司的有關(guān)研究報告稱“線切割加工對表面金相結(jié)構(gòu)產(chǎn)生不利的影響，實(shí)際上已經(jīng)改變了金相結(jié)構(gòu)。所以沖裁間隙對沖件的外廓尺寸精度有決定性的影響?！２煌瑳_模結(jié)構(gòu)類型，由于適用沖壓料厚及制造精度的差異，導(dǎo)致沖件的固定誤差有別。所以，各類沖模沖件誤差是由因定誤差、漸增誤差、系統(tǒng)誤差及偶發(fā)誤差等幾部分綜合構(gòu)成。沖模的初始誤差通常是沖模整個壽命中沖件誤差最小的。s related memoir called the line cut the processing contruction to have the disadvantageous influence to the superficialgold, in fact already changed the gold contruction. We must use theJin39。 and the punching part are punched with progressive die, the gap C=7%t (single edge) , initial accuracy are IT11, and have an more rough surface, even can see the gap with eyes. In the usual situation, flushes a material and its thickness t is theselection punching gap main basis. Once the designation gap haddetermined flushes the plane size the fixed error main body。在現(xiàn)場，確定沖模刃磨壽命的依據(jù)是沖件沖孔與落料的毛刺高度。沖件的極限誤差是具有極限偏差的沖件所具有的實(shí)際允許的最大尺寸誤差。此外，