A machining center is a highly automated multifunctional CNC machine tool with a tool magazine and automatic tool changer. Since machining centers are more expensive than ordinary machine tools, they are subject to more constraints, and whether the machine tool selection is reasonable is even more important. Better selection is the key to making good use of machining centers and realizing benefits. Before purchasing a machining center, these five key points need to be understood:
- Rigidity of the machining center Since the rigidity of the machining center will directly affect 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 specifications, so the rigidity of its structural design is also much higher than that of ordinary machine tools. When ordering, you can check and calculate according to the process requirements, the maximum allowable torque, power, shaft force and feed force, and the values provided by the manufacturer. In order to obtain 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. The whole machine of Pradi vertical machining center adopts A-shaped straddle structure, and the variable diameter is optimized, which has better rigidity.
- Machining accuracy of machining center Machining accuracy directly affects the quality of your products. When many people deny that your machine tool accuracy is not good, it will directly affect the decision of the buyer. 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, while the machining accuracy is the sum of errors caused by various factors of the entire process system, including the allowable error of the machine tool itself. When selecting, the evaluation method of process capability kp can be referred to as the basis for selecting accuracy. Generally speaking, the calculation result should be greater than 1.33.
- Selection of CNC system of machining center CNC system is the core brain of machining center operation. CNC functions are divided into basic functions and optional functions. Basic functions are necessarily provided, and optional functions will only be provided by manufacturers after users select these functions. The functions of the CNC system must be selected according to the performance requirements of the machine tool. When ordering, the required functions must be ordered in full without omission, and waste caused by low utilization rate should be avoided. At the same time, attention should be paid to the correlation between the functions. Among the available CNC systems, the performance varies greatly. It should be selected according to needs, and high indicators should not be pursued unilaterally to avoid waste. When selecting multiple machine tools, try to use the CNC system of the same manufacturer, so that operation, programming and maintenance are more convenient. Prady machining center mainly uses the CNC system of Fanuc and Siemens, which is also the CNC system widely used in the market.
- The number of coordinate axes and the number of linkage axes
The number of coordinate axes and the number of linkage axes should meet the typical workpiece processing requirements. The number of coordinate axes is also a sign of the grade of the machine. In general, for machine tools of the same manufacturer, the same specifications and the same precision, adding a standard coordinate axis will increase the cost by about 35%. Although increasing the number of axes can enhance the function of the machine tool, it is still necessary to pay attention to the process requirements and the balance of funds in the end. - Automatic tool changer and tool magazine capacity
The selection of automatic tool changer mainly considers tool change time and reliability. Short tool change time can improve productivity, but short tool change time generally means complex tool changer structure, high failure rate and high cost. Over-emphasizing tool change time will greatly increase costs and increase failure rate. According to statistics, about 50% of the failures in machining centers are related to automatic tool changers. Therefore, under the premise of meeting the use requirements, try to use automatic tool changers with high reliability to reduce the failure rate and the cost of the whole machine. The working quality of automatic tool changer and tool magazine capacity will directly affect the performance and quality of the machining center. The tool magazine capacity is based on the principle of meeting the needs of a complex machining part for tools.
