Five key points to choose a machining center

Since machining centers are far more expensive than ordinary machine tools, there are more factors to consider when purchasing, and the choice of machine tools is more important. The correct selection is the key to making good use of the machining center and making the machining center effective. When purchasing a processing center, it is particularly important to carefully examine these five key points:

 (1) Rigidity of machining center Since the rigidity of the machining center directly affects the production efficiency and the machining accuracy of the machine tool, the machining speed of the machining center is much higher than that of ordinary machine tools, and the motor power is also higher than that of ordinary machine tools of the same specification, so the rigidity of its structural design is also much higher than that of ordinary machine tools. . When ordering, check calculations can be made according to the process requirements, allowable torque, power, axial force and maximum feed force, and according to the values provided by the manufacturer. In order to obtain the high rigidity of the machine tool, it is often not limited to the size of the part, but a machine tool with 1 to 2 specifications larger than the part size is selected. 

(2) Machining accuracy of machining center Machining accuracy will directly affect product quality. When many people question the accuracy of machine tools, they will directly affect the buyer's decision. It should be noted that machining accuracy and machine tool accuracy are two different concepts. It is wrong to regard the position accuracy on the manufacturer's sample or product certificate as the machining accuracy of the machine tool. The position accuracy indicated on the sample or certificate is the accuracy of the machine tool itself, and the machining accuracy is the sum of the errors produced by various factors of the entire process system including the allowable error of the machine tool itself. When selecting models, refer to the evaluation method of process capability kp as the basis for selection of accuracy. Generally speaking, the calculation result should be greater than 1.33. 

(3) Selection of CNC system for machining center The CNC system is the core brain of the machining center operation, and the CNC functions are divided into basic functions and selection functions. The basic functions are inevitable, and the selected functions are only provided by the manufacturer after the user selects these functions. The function of the numerical control system must be selected according to the performance needs of the machine tool. When ordering, the required functions must be ordered without omission, and at the same time, to avoid waste due to low usage, and to pay attention to the correlation between the functions. Among the available CNC systems, the performance level varies greatly. It should be selected according to needs, and high targets cannot be pursued one-sidedly to avoid waste. When selecting multiple machine tools, use the same manufacturer's CNC system as much as possible to make operation, programming, and maintenance more convenient. 

(4) Number of coordinate axes and linkage axes Both the number of coordinate axes and the number of linkage axes should meet the requirements of typical workpiece processing. The number of coordinate axes is also one of the signs of machine tool grade. Under normal circumstances, adding a standard coordinate axis to a machine tool of the same manufacturer, specification and accuracy will increase the cost by about 35%. Although increasing the number of axes can strengthen the function of the machine tool, ultimately, pay attention to the process requirements and the balance of funds. 

(5) Automatic tool change device and tool magazine capacity The selection of automatic tool changer mainly considers the time and reliability of tool change. Short tool change time can improve productivity, but the tool change time is short. Generally, the tool change device has a complex structure, high failure rate and high cost. Excessive emphasis on tool change time will greatly increase the cost and increase the failure rate. According to statistics, about 50% of the failures of the machining center are related to the automatic tool changer. Therefore, on the premise of meeting the requirements of use, the reliable automatic tool changer should be selected as far as possible to reduce the failure rate and the cost of the whole machine. The working quality of the automatic tool change and the capacity of the tool magazine will directly affect the performance and quality of the machining center. The capacity of the tool magazine is based on the principle that a complex machining part needs tools.