What Principles Do CNC Machining Processes Need To Follow?

These principles are designed to improve the efficiency, precision and surface quality of CNC machining, reduce unnecessary clamping times and positioning errors, and thus improve overall machining performance. The CNC machining process needs to follow the following principles: 

1. The principle of maximum concentration and one-time positioning of the process

Generally, on CNC machine tools, especially on the machining center, the processing parts and processes can be concentrated to the greatest extent, that is, the parts should be completed as much as possible in a clamping Most or all of the processes that can be processed by the CNC machine tool, CNC machining tends to be process concentrated, which can reduce the number of machine tools and the number of workpiece clamping, reduce unnecessary positioning errors, and have high productivity. For the hole system processing with high coaxiality requirements, all the machining of the coaxial hole system should be completed by sequential continuous tool change after one installation, and then the holes in other positions should be processed to eliminate the influence of repeated positioning errors and improve the coaxiality of the hole system.

2. The principle of coarse first and then fine

When CNC machining is carried out, when dividing the process according to the machining accuracy, stiffness and deformation of the parts, the process should be divided according to the separation of rough and fine machining, that is, semi-finishing and finishing are carried out after the rough machining is completed. For a certain machined surface, it should be completed in the order of roughing-semi-finishing-finishing. During rough machining, it should give full play to the performance of the machine tool and the cutting performance of the tool under the condition of ensuring the processing quality, tool durability and rigidity of the machine tool - fixture - tool - workpiece process system, and try to use a larger number of cutting times to obtain the machining condition of each part of the margin before finishing as uniform as possible. Finishing mainly ensures the accuracy and surface quality of the parts, so usually the final contour of the parts should be continuously finished by the last tool during finishing. In order to ensure the quality of processing, under normal circumstances, the finishing allowance should be left 0.2-0.6mm, between rough and finishing, it is best to wait for a period of time, so that the deformation of the parts after rough machining can be fully recovered, and then finishing to improve the machining accuracy of the parts.

3. The principle of near first, then far, face before hole

According to the distance of the machining part relative to the tool setting point, in general, the part close to the tool setting point is processed first, and the part far away from the tool setting point is processed later, so as to shorten the tool moving distance and reduce the idle travel time. For turning, it is also beneficial to maintain the rigidity of the embryo or semi-finished product and improve its cutting conditions. For the machining of parts with both milling plane and boring hole, it can be carried out in the order of first milling plane and then boring. Because the cutting force is larger when milling the plane, the parts are easy to deform, first mill the surface and then boring, so that it has a period of time to recover, and then boring after its recovery and deformation, is conducive to ensuring the machining accuracy of the hole, secondly, if the first boring and then milling the plane, the orifice will produce burrs, flash, affect the assembly of the hole. 

Adhering to the fundamental principles of CNC machining is essential for achieving high precision, efficiency, and quality in manufacturing. By concentrating processes, following the rough-to-fine sequence, and optimizing toolpaths, manufacturers can significantly enhance their machining operations. Additionally, leveraging automation and implementing robust quality control measures further ensures consistent and reliable results.