What Are the Requirements for Raw Material in Metal Spinning?

(1) Spinning requires uniformity of raw material properties. The uneven metal structure and stress distribution of the raw material will cause uneven deformation of the raw material in the spinning part, which will cause the spinning part to bulge or break, and make the material strength of different parts different. In addition, the dimensional accuracy of spinning parts will decrease and the ovality will increase.

(2) Spinning requirements for raw material dimensional accuracy

① Influence of raw material wall thickness deviation: For spinning forming of cylindrical parts, due to excessive variation of raw material wall thickness, the straightness of spinning parts will be affected, and even bending will occur. For conical parts and curved generatrix-shaped parts, the wall thickness deviation of the prefabricated raw material will prevent the spinning process from strictly following the sinusoidal law, resulting in a decrease in the internal and external precision of the spinning part and an increase in the wall thickness deviation. Therefore, the wall thickness deviation of the raw material should usually be less than 0.1mm.

② Raw material inner diameter deviation: If the raw material inner diameter deviation is too large, it is easy to cause the ellipticity and diameter expansion of the spinning part.

③ The ellipticity of the prefabricated raw material and the misalignment of different parts of the raw material.

④ Non-perpendicularity between the bottom of the raw material and its axis.

⑤ The gap between the raw material and its mandrel.

(3) Spinning requirements for the inner and outer layers of the raw material

① There must be no interlayers, inclusions, cracks and looseness inside the raw material, otherwise, the spinning parts are prone to defects such as fracture, internal cracks and microcracks. Therefore, some large raw materials and raw materials with welds need to be inspected for flaw detection.

② There should be no defects such as spots, processing marks, cracks and burrs on the surface of the raw material, otherwise, the surface of the spinning part will have scales. In the case of large deformation, fracture will also occur.

③ Dirt and scales on the surface of the raw material should be removed to avoid damage to the workpiece and contamination of the lubricant.