What matters should be paid attention to in automobile parts processing?

Auto parts processing needs to be paid attention to in many aspects, such as precision control, material selection, process planning, etc. The following are specific matters:

accuracy control

Dimensional accuracy: the dimensional accuracy of automobile parts directly affects the matching accuracy with other parts, and then affects the performance and reliability of the whole vehicle. For example, the accuracy of the bore size of the engine cylinder block is extremely high, and any slight deviation may lead to problems such as engine air leakage and power reduction. High-precision processing equipment and advanced processing technology, such as CNC machining, precision grinding, etc., should be used in processing, and real-time monitoring and calibration should be carried out through accurate measuring instruments.

Form and position tolerance: the shape and position tolerance of parts are equally critical, such as cylindricity and straightness of crankshaft and coaxiality between journals. In order to ensure the form and position tolerance, it is necessary to optimize the clamping mode and machining path, reduce the deformation and vibration during machining, and adopt high-precision fixtures and positioning devices to ensure the position accuracy of parts during machining.

Material selection

Performance matching: Select appropriate materials according to the use environment and functional requirements of parts. For example, parts that bear high stress and impact load, such as automobile half shafts, need to be made of high-strength and high-toughness alloy steel; For some parts that require good wear resistance, such as engine camshaft, alloy cast iron with good wear resistance or steel with hardened surface can be used.

Material quality: ensure the quality of the selected materials is stable and reliable, and strictly control the chemical composition, purity and internal structure of the materials. Inferior materials may lead to premature failure of parts in use, affecting the safety and durability of automobiles. When purchasing materials, it is necessary to purchase from regular suppliers, and provide material quality certification documents, and at the same time carry out necessary material inspection and testing, such as chemical composition analysis and mechanical properties testing.

Processing technology planning

Reasonable arrangement of working procedures: according to the structural characteristics and precision requirements of parts, make a reasonable processing route. Generally speaking, rough machining is carried out first to remove most of the allowance, and then semi-finishing and finishing are carried out to gradually improve the accuracy and surface quality of parts. In the process of machining, auxiliary processes such as heat treatment and surface treatment need to be arranged reasonably to improve the material properties and improve the wear resistance and corrosion resistance of parts. For example, for some precision gears, quenching and tempering are carried out after rough machining to improve the comprehensive mechanical properties of the materials, then finishing is carried out, and finally surface carburizing and quenching are carried out to improve the hardness and wear resistance of the gear surface.

Optimization of process parameters: select appropriate cutting parameters, such as cutting speed, feed rate and cutting depth, to improve machining efficiency and quality and reduce tool wear and machining cost. At the same time, cutting tools and cutting fluids should be selected reasonably according to different processing materials and technological requirements. For example, when machining aluminum alloy parts, diamond cutter or cemented carbide cutter can be selected, and special aluminum alloy cutting fluid can be used to improve the surface quality and tool life.

Surface quality control

Surface roughness: the surface roughness of automobile parts has an important influence on its friction performance, sealing performance and corrosion resistance. For example, the surface roughness of engine piston ring is required to be low, so as to reduce the friction with the cylinder wall and improve the efficiency and reliability of the engine. In order to obtain good surface roughness, it is necessary to adopt appropriate cutting parameters and tools in the machining process, and carry out necessary surface finishing, such as grinding and polishing.

Surface integrity: In addition to surface roughness, we should also pay attention to the surface integrity of parts, including the structure of surface layer and residual stress. The residual stress generated during machining may lead to problems such as deformation and cracking of parts during use. Therefore, the residual stress should be controlled and eliminated through reasonable processing technology and appropriate heat treatment technology, such as vibration aging and tempering.

Quality inspection and control

First article inspection: before batch processing, the first product is processed for comprehensive inspection, including dimensional accuracy, shape and position tolerance, surface quality and other aspects. Only after the first piece has passed the inspection can mass production be carried out to avoid mass quality problems.

In-process inspection: During the processing, the spare parts shall be sampled regularly, and the quality problems in the processing shall be found in time, and corresponding measures shall be taken for adjustment and improvement. For example, in the process of NC machining, the machining size can be monitored in real time through the online measurement system, and the tool compensation or machining parameters can be adjusted in time when the deviation is found.

Finished product inspection: conduct a comprehensive quality inspection of the processed parts to ensure that they meet the requirements of design drawings and related standards. The inspection contents include visual inspection, dimensional accuracy measurement, shape and position tolerance detection, mechanical performance test, sealing test and so on. Only qualified parts can enter the assembly process.

Cleaning and protection

Cleaning during machining: During machining, the working area and parts should be kept clean to prevent impurities such as chips and oil stains from adhering to the surfaces of parts, which will affect their surface quality and assembly accuracy. Regularly clean machine tools and processing equipment, remove chips and oil stains in time, and use special cleaning solution to clean parts.

Protection of finished products: During the storage and transportation of processed parts, appropriate protective measures should be taken to prevent them from being damaged by bumps, scratches and corrosion. For example, some precision parts can be protected by plastic film and antirust oil, and parts that are easy to rust can be treated by electroplating and phosphating, and stored in a dry and ventilated environment.