What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Slotted Round Head Wood Screws GB 99-86 Slotted Countersunk Head Wood Screws GB 100-86 Slotted Half Countersunk Head Wood Screws GB 101-86 Hexagon Head Wood Screws GB 102-86 Cross Recessed Round Head Wood Screws GB 950-86 Cross Slotted countersunk head wood screws GB 951-86 Cross recessed countersunk head wood screws GB 952-86
Commonly used screw materials in my country are No. 45 steel, 40Cr, ammoniated steel, 38CrMOAl, superalloy, etc. 1) No. 45 steel is cheap and has good processing performance, but poor wear resistance and corrosion resistance. Heat treatment: quenched and tempered HB220-270, high-frequency quenched HRC45--48. 2) The performance of 40Cr is better than that of No. 45 steel, but it is often plated with a layer of chromium to improve its corrosion resistance and wear resistance. However, the requirements for the chrome plating layer are relatively high. If the plating layer is too thin, it is easy to wear, and if it is too thick, it is easy to peel off. After peeling off, it will accelerate the corrosion, and it has been rarely used. Heat treatment: quenched and tempered HB220—270, hard chrome plated HRC>553) nitrided steel, 38CrMoAl have excellent comprehensive properties and are widely used. Generally, the nitride layer reaches 0.4-0.6 mm. However, this material has low resistance to hydrogen chloride corrosion and is relatively expensive. 4) The superalloy material is superior to other materials. This material does not need coating, and is mainly used for the raw halogen-free screw of injection molding machine. The material has high oxidation resistance and corrosion resistance.
Bolts with low hardness and strength. Generally, ordinary bolt materials are produced with ordinary screw wires. The hardness, strength, tensile strength and torsion force of ordinary bolt materials are not very high. High-strength bolts generally refer to high-strength bolts. Its own screw material, bolt material, and bolt material are relatively good, and the hardness is relatively high, and after the production is completed, the bolts will be hardened. Make the bolts meet the grade strength requirements of high-strength bolts.
The side gear thrust washer used in the automobile differential is a flat washer, which is installed between the differential housing and the side gear to prevent the side gear from retreating. Due to the high-speed rotation of the side gear when the differential is working, it is necessary to ensure that the contact surfaces on both sides of the flat gasket are well lubricated.
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