Because machining center is far costlier than general accuracy machine tool, get so restrict element more, machine tool choice is logical more it is important to show. Correct type selecting is to use the good machining center, key that makes machining center produces beneficial result. When buying machining center, inspect dot of this 5 gist to weigh particularly seriously should: One, the stiffness of machining center Because machining center stiffness can affect the treatment precision that manufactures efficiency and machine tool directly, the treatment speed of machining center greatly prep above general accuracy machine tool, electromotor power also the general accuracy machine tool that prep above is the same as norms, the stiffness that accordingly its structure designs also outclass general accuracy machine tool. Force of craft requirement, permission torque, power, axis and feed force maximum can be pressed when ordering goods, the numerical value that offers according to manufacturer undertakes checking computations. To obtain the tall tigidity of the machine tool, often not dimension of spare parts of bureau be confined to, and choose dimension of opposite spare parts big the 1 machine tool to 2 norms. 2, the treatment precision of machining center Machine precision, affect your product quality directly, when a lot of people are denying your machine tool precision is no good, with respect to the decision of purchaser of can immediate impact. Wanting an attention to machine precision and machine tool precision is two different ideas. Get on manufacturer home example or the positional precision on product certificate of approval regards as the treatment precision of the machine tool is a mistake. The positional precision that indicates on example or certificate of approval is the precision of machine tool itself, and treatment precision is the error total that all sorts of element place produce the whole machining complex that includes place of machine tool itself to allow an error inside. When type selecting, can consult the assess method of process capability Kp regards the type selecting of precision as the basis. Say commonly, computation should is more than as a result 1.33. 3, the choice of system of machining center numerical control Numerical control system, it is the core cerebra that machining center operates, cent of numerical control function is basic function and choice function. Basic function is provided necessarily, and after choosing a function to choose these functions when the user only, manufacturer just can be offerred. To numerical control systematic function must need to choose according to the function of the machine tool, the function that a need wants already when ordering is ordered complete, cannot omit, avoid utilization rate to create waste not high at the same time, still need to notice the associated sex between each function. In the numerical control system that can supply a choice, function discretion difference is very big. Answer to choose according to need, cannot seek tall target one-sidedly, lest create waste. When type selecting of much stage machine tool, choose the numerical control system of same manufacturer as far as possible, such operations, process designing, maintenance is more convenient. 4, coordinate number of axle and linkage number of axle Coordinate number of axle and linkage number of axle all should satisfy typical workpiece to machine a requirement, the amount of reference axis also is a mark of machine tool class. Usually, with the manufacturer, machine tool that is the same as norms, coequal precision, increase reference axis of a standard, cost raises about 35% the left and right sides. Although increase number of axle but the function of aggrandizement machine tool, still want finally to notice craft requirement and capital are balanced. 5, change knife device and knife library size automatically The option that trades knife unit automatically basically considers to change knife time and dependability. The time that change a knife is short can improve productivity, but the time that change a knife is short, construction of the common unit that change a knife complex, fault rate cost is tall, high, time of knife of beyond the mark strong exchange can make expenses rises substantially and make fault rate rises. Have about in the breakdown that occupies statistical machining center 50% with change knife device automatically to concern, because this is below the premise of contented use requirement, choose dependability as far as possible tall trade knife unit automatically, with reducing fault rate is mixed overall cost. The working quality that changes a knife automatically and knife library capacity can affect the performance characteristics of machining center, quality directly. Knife library capacity it is a principle in order to satisfy spare parts of a sophisticated treatment to the need of cutting tool.