Stainless steel machine screws fracture reason and quality identification method
Stainless steel machine screws are a common type of fasteners. Stainless steel machine screws break when used. What is the reason? How to identify the quality of Stainless steel machine screws? Let's take a look at the causes and quality identification methods of Stainless steel machine screws breaks. I hope to help everyone.
Stainless steel machine screws fracture reason
Under normal circumstances, Stainless steel machine screws are not easy to break when used. Only in special cases, Stainless steel machine screws will break. Why do Stainless steel machine screws break? What is the real reason for Stainless steel machine screws fracture? According to the summary, De Special Alloys has four kinds of common fracture conditions for Stainless steel machine screws.
1. When the customer uses Stainless steel machine screws, the force is too large. Generally, you can do a lower torque test to see what the minimum breaking force is, and then adjust the torque. If the screw torque is required to be high, the screw should be heat treated. At present, the stainless steel 410 material can be heat treated, the heat-treated stainless steel 410 screw, the surface hardness HV580-680, and the core hardness is HV350-450.
2. the quality of raw materials used in Stainless steel machine screws, Stainless steel machine screws wire quality is not good. There are a lot of impurities, impure, resulting in insufficient hardness of Stainless steel machine screws
3. see if the pre-hole is suitable, the pre-hole will break when the small screw is broken. Therefore, when we buy Stainless steel machine screws, we must clearly recognize them, in case we buy back inferior products, and bring unnecessary trouble to ourselves during use.
4. the production of Stainless steel machine screws process problems. For example, the Stainless steel machine screws with eccentricity and the Q value are too deep and the R position is too small during the manufacturing process.
Method of identifying Stainless steel machine screws
the amount
The quantity refers to the measurement with a ruler. The fasteners are divided into standard parts and non-standard parts, and the standard parts have corresponding specifications and dimensions. The national standard and the German standard are used more in the market. Under different standards, each grade of Stainless steel machine screws has different specifications. The length and diameter can be measured using a vernier caliper according to the corresponding standard. The measurement results of high quality Stainless steel machine screws should be consistent with the corresponding standard parameters.
Look
Seeing is the observation of the appearance, surface treatment, tooth marks and signs of Stainless steel machine screws. Good quality Stainless steel machine screws have a smooth appearance and uniform color. No rust and oil, the teeth are neat and the tooth distance is even. There is no headshot on the head, no cracks on the chamfer, and the tail is balanced. There should also be no burrs in the walls of the holes. The head of the head, dark spots on the surface, delamination, etc. indicate that the quality of the Stainless steel machine screws is not good.
If it is a non-standard part, it is necessary to check whether the measurement result matches the standard parameter of the requirement, and the unmatched person needs to be reworked.
Measurement
The test refers to the use of a hardness tester to test the hardness or to conduct a professional salt spray test. Stainless steel machine screws hardness standards can be measured by Vickers hardness, Brinell hardness, Rockwell hardness, and surface hardness. It can be measured using a Leeb hardness tester, a Brinell hardness tester, a Rockwell hardness tester, or a Vickers hardness tester. In general, low-strength Stainless steel machine screws such as 4.8 and 6.8 are tested by Brinell hardness, and grade 8.8 is tested with Rockwell hardness. Generally, the hardness of 12.9 is HRC39-44.
The salt spray test requires a salt spray tester. The different salt spray times of different grades and different types of Stainless steel machine screws are also different. Stainless steel machine screws salt spray test time is generally 24-72 hours.
The above is about the reasons for the fracture of Stainless steel machine screws and the method of quality identification. I hope that everyone can understand the reasons for the fracture of Stainless steel machine screws and the method of quality identification. It is helpful for everyone to choose Stainless steel machine screws.
