Cold machining: cold machining is called cold working which is divided according to different machining methods. It is used in cutting and pressure machining.
Hot working: generally speaking, mechanical processing that causes chemical changes in workpieces during a process above or below normal temperature is called hot working and is often used for heat treatment, calcination, casting and welding.
The production process of precision machining refers to the whole process from raw materials (or semi-finished products) to products. It is used in machining production, including transportation and preservation of raw materials, production preparation, rough processing, parts processing and heat treatment, product assembly and commissioning, painting and packaging. The machining of mechanical parts is produced through a variety of mechanical equipment, such as numerical control machine tools, lathes, milling machines, grinding machines, wire cutting, electric sparks, and other mechanical equipment. The inherent machining accuracy of all kinds of equipment is different, so it is necessary to achieve certain accuracy. In the process of processing, we need to select the appropriate machining process and machining equipment.
Matters needing attention in Precision Machining:
1. In order to ensure the precision of precision machining, rough machining and finishing machining should be carried out separately. As a result of rough machining, a large number of workpieces are subjected to cutting force, large clamping force, more heat, easy to cause surface hardening, the workpiece has a very large internal stress, if finishing and rough processing is continuous, The precision of precision parts after finishing will be redistributed with stress and will be lost soon. For some parts with high machining accuracy. Low-temperature annealing or aging should be carried out after rough machining and before finishing to eliminate internal stress.
2. Select reasonable machining equipment: the main process of rough machining is to cut off most of the machining allowance without requiring higher machining accuracy. Therefore, roughing machine tools only need high power, low precision machining. Finishing requires more sophisticated machine tools. Roughing and finishing on different machine tools can not only give full play to the performance of the equipment, but also prolong the service life of precision machine tools.
3. Heat treatment is often needed in the process of precision machining. The process of heat treatment is arranged as follows: in order to improve the cutting performance of metals, such as annealing, normalizing, tempering, etc., usually takes place before machining. In order to eliminate internal stress, such as aging treatment and tempering treatment, generally after rough processing, before finishing. In order to improve the mechanical properties of parts, Carburizing, quenching, tempering and so on, generally after mechanical processing.