Precision machining is a process of using processing machinery to change the shape or performance of a workpiece.
According to the temperature state of the workpiece to be processed, it can be divided into cold processing and hot processing during use. Generally processing at room temperature, and does not cause chemical or phase changes of the workpiece, it is called cold processing.
Precision machining is generally higher or lower than normal temperature processing, which will directly cause the chemical or phase change of the workpiece, which is called thermal processing. Cold processing can be divided into cutting processing and pressure processing according to the difference in processing methods. Thermal processing commonly includes heat treatment, forging, casting and welding. The first is the requirement of material hardness. For some occasions, the higher the hardness of the material, the better, but it is limited to the hardness requirements of the machined parts. The machined material should not be too hard. If it is harder than the machine part, it cannot be processed.
Precision machining manufacturers introduce the operation steps of precision machining.
- 1. Finishing processing: This processing principle is roughly some grinding and polishing processing, which is usually a step after the product is completely structured.
- 2. Face before hole: When making precision mechanical parts, for a workpiece such as a bracket, it needs to perform plane processing and mechanical hole processing. In order to make the accuracy error of the processed hole smaller, process the plane first Post-machined holes help reduce errors.
- 3. Divide the processing stages: When the products are precision mechanical parts, they need to be processed to different degrees according to different product requirements. The degree of processing needs to be divided. If the accuracy requirements are not high, then a simple roughing stage will do. Product schedule requirements are becoming more and more strict, and semi-finishing and finishing stages will be carried out in the follow-up.
- 4. Benchmark first: When using mechanical equipment to process the product, a datum surface must be determined so that there can be a positioning reference during subsequent processing. After the datum surface is determined, the datum surface must be processed first. In precision mechanical parts, many workpieces are not produced at one time, but when the workpiece is produced, it is just a rough model.
There are three specific treatment principles for precision machining, as follows:
- (1) In order to ensure the machining accuracy, roughing and finishing are best performed separately. Because of the large amount of cutting during rough machining, the workpiece is subjected to large cutting force, clamping force, heat generation, and the machined surface has a significant work hardening phenomenon, there is a large internal stress inside the workpiece, if rough or rough machining Continuously, the precision of the parts after finishing will be quickly lost due to the redistribution of stress. For some parts that require high machining accuracy. After rough machining and before finishing, low temperature annealing or aging treatment procedures should also be arranged to eliminate internal stress.
- (2) Choose equipment reasonably. Rough machining mainly cuts off most of the machining allowance and does not require high machining accuracy. Therefore, rough machining should be carried out on a machine with greater power and less precision, and the core machining process requires higher precision. Machine processing. Rough and fine machining are processed on different machine tools, which can not only give full play to the equipment capabilities, but also extend the service life of precision machine tools.
- (3) In the machining process route, a heat treatment process is often arranged. The location of the heat treatment process is arranged as follows: In order to improve the cutting performance of the metal, such as annealing, normalizing, quenching and tempering, etc., it is generally arranged before mechanical processing. In order to eliminate internal stress, such as aging treatment, quenching and tempering treatment, etc., it is generally arranged after rough machining and before finishing. In order to improve the mechanical properties of parts, such as carburizing, quenching, tempering, etc., it is generally arranged after machining. If there is a large deformation after heat treatment, the final processing procedure must be arranged.
Safety precautions in machining
- (1) Easy to operate, reduce walking back and forth, avoid unnecessary bending and tiptoe movements.
- (2) The positioning is accurate and reliable to prevent malfunctions due to slight vibration.
- (3) The movement direction of the operating parts of the machine tool equipment and the movement direction of the operated parts must comply with the regulations, and have simple symbols and signs.
- (4) Install the necessary interlocking mechanism to prevent uncoordinated actions of the operating parts and accidents caused by uncoordinated operation of multiple persons.
- (5) The structure and arrangement of handles, handwheels, and buttons must comply with regulations. The start button should be installed in the case or a guard ring to prevent accidental touch. The handwheel and handle installed on the shaft rod will hurt people when the knife is automatically moved along with the shaft rotation. Therefore, an automatic release device should be installed.
