Ordinary precision soft screws are widely used, such as 7~8 level positioning screws and manual feed screws on machine tools. Due to their convenient processing and low manufacturing cost, the performance requirements of the materials used are not high, and they are mostly used for some medium carbon steel and medium carbon low alloy steel.
For high-precision precision soft screws, precision screws with accuracy above level 6 and hardness below 35HRC are mostly used in structures with light loads, low operating frequencies and good lubrication conditions. It often uses steel with a high carbon content. In addition to the similar conditions to ordinary precision soft screws, its requirements for materials also require good grinding performance, not easy to burn the surface, low sensitivity to cracking, and low grinding surface roughness.
For high-precision hard screws, the core is required to have a certain strength and toughness, and the surface raceway must have high hardness to ensure sufficient load-bearing capacity and be able to drive heavy loads to move freely. This requires that the tensile strength of the material used must reach 700~1000Mpa, and it should also have a certain toughness and precision stability. The workpiece is also required to have good cold and hot processing performance during the manufacturing process.