What is the machining allowance for precision CNC machining?
In precision CNC machining, in order to process qualified parts, a part of the metal must be cut from the blank, and the thickness of that layer of metal is called the machining allowance. Machining allowance can be divided into process allowance and tota
In precision CNC machining, in order to process qualified parts, a part of the metal must be cut from the blank, and the thickness of that layer of metal is called the machining allowance. Machining allowance can be divided into process allowance and total allowance. The thickness of the metal layer that needs to be removed in a certain process is called the machining allowance of the process. The total margin that needs to be removed from the blank to the finished product is called the total margin, which is equal to the sum of the margins of each process on the corresponding surface.
The purpose of leaving a machining allowance on the workpiece is to remove the precision CNC machining errors and surface defects left by the previous process, such as the chilled layer, pores, and sand layer on the surface of the casting, and the oxide scale and decarburized layer on the surface of the forging. Surface cracks, internal stress layer and surface roughness after cutting. Thereby improving the accuracy and surface roughness of the workpiece.
The size of the machining allowance has a greater impact on the processing quality and production efficiency. Excessive machining allowance not only increases the labor of machining, reduces productivity, but also increases the consumption of materials, tools, and electricity, and increases the cost of precision CNC machining. If the machining allowance is too small, the defects and errors of the previous process cannot be eliminated, and the clamping errors during the processing of this process cannot be compensated, resulting in waste products. The selection principle is to make the margin as small as possible under the premise of ensuring quality. Generally speaking, the more finishing, the smaller the process margin.