Should be familiar with a spare parts above all the action in the product, position, assemble relation and working requirement, make clear each Hunan technology asks to assemble the influence of quality and performance characteristics to the spare parts, find out the main technical demand with the key, undertake an analysis to part drawing appearance next. (1) checks the integrality of part drawing and validity to be after appearance of understanding spare parts and structure, should check spare parts view enough, expression is clear, whether does scale accord with national level, dimension, public errand and the tagging that the technology asks are reasonable wait. (The technology that the technology of 2) spare parts asks to analyse a spare parts asks to include following a few respects: Machine dimension precision of the surface; Basically machine appearance precision of the surface; Basically machine the mutual position precision between the surface; Machine the other requirement of exterior surface roughness and exterior quality respect; Heat treatment requirement; Other asks (like dynamic balancing, did not note round role or pour wine cup, go the) such as requirement of burr, semifinished product. Should notice to analyse these requirements to be below the premise that assures performance characteristics whether economy is sound, in existing production the condition falls whether implementation. The technology that should analyse main surface particularly asks, decided part process because of the treatment of main surface roughly outline. (The mechanical function of the qualitative itself of semifinished product material that the data analysis of 3) spare parts analyses place to offer namely and heat treatment condition, of semifinished product cast character and by the material hardness of treatment place, whether to have white mouth, mix arenaceous, loose etc. Judge the difficult easy extent that its machine, provide a basis to choose cutting tool material and cutting dosage. Picks spare parts material should economy is sound, cutting performance is good, satisfy the requirement of performance characteristics. (The tagging with reasonable 4) the important measure on dimension ① part drawing should be tagged directly, and should make craft fiducial as far as possible when treatment as fiducial as the design coincide, accord with the principle with dimension the shortest cable length. If pursue 1 in the dimension of piston annulus chamfer is important measure, its width should direct outpour. The dimension that tags on ② part drawing should facilitate measure, what do not measure plane hard from line of axes, center, hypothesis is fiducial tag dimension. If pursue 2 in the deepness of hub keyway, have dimension C only tag ability to facilitate measure with callipers or example. The dimension on ③ part drawing should be not tagged enclosed, lest produce contradiction. If the graph is shown 3 times, already tagged δ of ± of pitch dimension A and α of δ of angle α ± , the coordinate dimension of axis of a X, Y cannot be tagged casually. Machine to go to the lavatory sometimes, can come out by dimension catenary computation, tag inside parentheses, as the referenced dimension when treatment. Assorted free measure is not on ④ spare parts, should press treatment order as far as possible from craft fiducial outpour. If pursue the tine axle of 4, graph (the expression of A) major dimension wants the method classics conversion, and cannot measure directly. And graph (the tagging of B) means, agree orderly with treatment, facilitate treatment is measured again. Graph 1 direct mark is paid attention to want dimension to pursue of 2 keyway deepness tag a graph 3 aperture center is apart from tag (A) (B) graph 4 tag free dimension orderly by treatment (A) wrong (B) treatment surface is not each on correct ⑤ spare parts, and rather than can have measure of a connection only between treatment face and treatment face. If pursue 5 in be shown, graph (A) notes a way mediumly unreasonable, can make sure a dimension accords with design requirement only, the others dimension may out of tolerance. And graph (dimension A is tagged in B) when machining face Ⅳ , give assure, other is not the position that machines a face to be tagged directly, assure when cast. (A) (b) pursues the dimension between face of 5 blame treatment and treatment face is tagged (A) mistake (B) is correct CNC MillingCNC Machining