In order to effectively realize the interchangeability during the manufacturing process of precision machinery, in the process of manufacturing the parts, it is necessary to effectively make the geometry of the parts and the dimensions of the parts consistent. It is not a requirement that the score be exactly the same, as long as the size, geometry, etc. of the part are controlled within an allowable range, so that the combination of the part and other parts will have the same combination of properties. The allowed error range is the geometric position tolerance.
1. Geometric accuracy
The accuracy of the geometric shape refers to the accuracy of the geometrical shapes of the surfaces or axes that make up the part, such as whether the line is straight, whether the surface is flat, and whether the positive cross section on the cylinder is round. The allowable range of variation is represented by the “formal position tolerance”, and the smaller the shape position tolerance number, the higher the shape accuracy.
2. Dimensional accuracy
Analysis of precision parts processing manufacturers, the dimensional accuracy refers to the precision of the size of the parts after processing, expressed as "dimension tolerance". When the parts are the same size, the higher the precision, the smaller the tolerance number.
3. Position accuracy
Accuracy of precision parts machining position refers to the accuracy of the mutual position between the components of the surface, such as whether the two planes are parallel, whether it is vertical, whether the two axes are coaxial or not, is represented by “position tolerance”.
The above-mentioned shape and position tolerances are referred to as "formal position tolerances."
Precise mechanical finishing machining parts on CNC machine tools, under normal circumstances the craftsmen get their original data is a parts drawing, according to the parts drawing, can be the shape of the parts, dimensional accuracy, surface roughness, workpiece material, blank type and heat treatment Analysis of conditions, etc., and then select the machine tool, tool, determine the positioning and clamping device, processing method, processing sequence and cutting amount.
In determining the process, we should fully consider the command functions of the CNC machine tools used, give full play to the efficiency of the machine tool, so that the processing route is reasonable, the number of fewer passes and processing time is short. In addition, relevant technical documents, such as CNC machining process cards, CNC tool cards, and path planning, should also be filled out.