Stainless Steel Precision Parts
This stainless steel part is a carrier part on the automation equipment. The structure of the part has multiple positioning pin holes, countersunk holes, and threaded holes, which play an important role in connecting with other parts of the equipment. It is positioned by pins and tightened with screws. The precision carrier is driven to do work through the operation of the equipment, and at the same time, it drives other connecting stainless steel parts to achieve closed movement. This type of part is mainly used in food automation assembly line operations and assembly and testing equipment. 304L stainless steel is the most widely used chromium-nickel stainless steel, with good corrosion resistance, heat resistance, low-temperature strength, and mechanical properties; no heat treatment hardening phenomenon (use temperature -196 ℃ ~ 800 ℃). Corrosion-resistant in the atmosphere is one of the preferred materials in the food field.
Deformation Analysis Of CNC Machining Stainless Steel Precision Parts
Stainless steel is a common material, and machining deformation is also a common problem. It may be due to poor clamping force during the CNC machining process, which may lead to the deformation of parts. In order to avoid this situation, it is necessary to correctly clamp the clamping point and select the appropriate clamping force according to the position of the clamping point.
Try to keep the clamping point consistent with the support point, let the clamping force act on the support, and the clamping point should be as close as possible to the machined surface, so that it is not easy to cause deformation due to clamping.
When the workpiece has clamping forces in several directions, the sequence of clamping forces needs to be considered. In addition to completing the above steps, it is necessary to increase the contact area between the workpiece and the fixture or use the axial clamping force to increase the rigidity of the part. This is the most effective way to solve the problem of clamping deformation; It may also be that the cutting parameters are unreasonable, and the workpiece will be affected by the cutting force during the cutting process. This is an elastic deformation in the direction of the force.
Elastic deformation can be improved by adjusting the tool type, cutting speed, and feed. When finishing, the tool is required to be sharp, which can reduce the frictional resistance between the tool and the workpiece, and can also improve the heat dissipation capacity of the cutting workpiece, reduce the residual internal stress on the workpiece, and reduce the cutting depth and line spacing;
The material itself has a relatively balanced internal stress state. Although the shape of the parts is relatively stable at this time, the internal stress of stainless steel parts with a large amount of roughing will change after rough machining and during heat treatment, and the workpiece needs to regain the force balance. To this end, the stabilization of the internal structure can be straightened by heat treatment, and then the finishing process can be carried out.
Why Does Precision Machining Need To Remove Internal Stress?
In the processing of precision parts, after many stainless steel parts are processed, they are checked and confirmed on the machine, and they are all perfectly in line with the standard.
However, after leaving the lathe, when the inspection or the next process is carried out again, it is found that the size has quietly changed, and a perfect product has become a defective product.
In fact, this is the problem of process order. We only consider the processing technology, but fail to consider the characteristics of the material itself, resulting in changes in the internal structure of the material after the stainless steel parts are processed, resulting in processing deformation, resulting in out of tolerance. This phenomenon occurs everywhere in stainless steel.
To avoid this kind of deformation, the stress relief annealing process is indispensable. Stress relief annealing is to heat steel or various metal mechanical parts to a certain temperature, keep it for a period of time, and then slowly cool down so that a heat treatment process close to the equilibrium state structure can be obtained.
In the machinery manufacturing industry, annealing is usually used as a preliminary heat treatment process in the workpiece manufacturing process.
In the actual processing and production process, the application of the stress relief annealing process is more than that used above.
Hot forging rolling, casting, processing all kinds of cold deformation, cutting or cutting, welding, heat treatment, machine parts, and components, even without changing organization status, keep cold work, hot, or under the condition of surface hardening of steel or machine parts for low-temperature heating, to remove all or part of the internal stress, reduce the deformation and cracking tendency of the technology, Both can be called stress relief annealing.