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Why should we leave machining allowance on CNC machined parts?

Latest company news about Why should we leave machining allowance on CNC machined parts?

As various processing technologies appear on the market, we are slowly becoming familiar with them, or recognizing them. In industry, CNC processing is still a processing technology that is widely used. However, according to many users, machining allowances are left on CNC machined parts during production. Why do they do this? The following is an introduction to titanium processing parts companies.

The thickness of the metal layer removed in each process of CNC machining is called the machining allowance between processes. For torsions such as outer circles and holes, the machining allowance is considered from the diameter, so it is called symmetrical allowance (ie, two-sided allowance), that is, the thickness of the actual metal layer removed is half of the diameter machining allowance. The machining allowance of the plane is the single-sided allowance, which is the actual thickness of the metal layer removed.

The goal of the residual machining allowance of the workpiece is to remove the remaining machining errors and external defects from the previous process, such as the outer chilled layer of the casting, pores, interlayers, the outer oxide scale of the forging, the decarburized layer, external cracks, and the internal stress layer after cutting. and external roughness, etc. Then, the accuracy and external roughness of the workpiece are improved. The size of the machining allowance has a great impact on the processing quality and production capacity.

Excessive machining allowance not only increases the labor volume of mechanical processing and reduces productivity, but also increases the consumption of materials, indicators and electricity. CNC processing increases processing costs. If the machining allowance is too small, it will be too late to eliminate various defects and errors in the previous process, and it will also be too late to compensate for the clamping errors during this process, resulting in scrap. The standard is to minimize margins under CNC machining that ensures quality. Generally speaking, the more processing, the smaller the process allowance.

When determining the CNC processing sequence, it must be clear whether the parts are pre-processed before processing. Preprocessing is often completed by ordinary machine tools. If the accuracy of the blank is high, the positioning is reliable, or the machining allowance is sufficient and uniform, pre-processing can be eliminated and processed directly on the CNC machine tool. At this time, the distinction between CNC machine tool processes must be considered based on the accuracy of the rough rough reference of the blank, so one process or divided into several processes can be completed.