There are several areas where mistakes are prone to occur in the metal spinning industry. Generally, beginners have all tried these when they first enter this field. This article mainly introduces some common knowledge about ordering spinning materials, designing spinning accuracy, and inspecting spun products. Read this article carefully to avoid making mistakes at work and causing losses to the factory's profits.

1. Purchase materials＞

Many beginners in spinning tend to make mistakes when purchasing materials. Commonly used spinning materials include aluminium, iron, copper, brass and stainless steel. When purchaser buy materials, there are basic technical knowledge you must know.

① The differences between cold-rolled plates and hot-rolled plates

● The surface of Cold rolled is more smooth, the hardness of cold rolled is harder.

● Hot-rolled plates have pores and sand holes inside, and are prone to cracking during spinning forming, which is not as good as cold-rolled plates.

② Metal Sheet Types

● The metal spinning performance of All the mild steel is similar, no matter DC01,DC02,DC03,DC04, Q235,Q275,Q345, the ductility is good, DC04 spinning performance is best.

● Aluminum have many types, 1060, 1070, 1100, 3003, 5052, 5082, 6061, 6063, 6082. the 1060,1070,1100 type is the best spinning performance, but the very type have different state, such as 1060 aluminum has F state, O state(annealing

), H state ( work hardening), W state, T state. Metal spinning need to buy the O state, if you buy other state, it is hard to spin.

● Stainless steel types have 201，304，316，you also need to buy the right type to spin, such as 304 type have many classification, such as 304 DDQ(deep drawing quality ), 304BQ (brused quality), we need to buy 304 DDQ, It can be deep drawing, but others just can be spin less height as the ductility is not enough.

● Copper and brass have many types, but the Tu1 and Tu2 copper is good to spin, H65 Brass is good to spin.

③ Metal tube

● Aluminum seamless tube is 6061 or 6063，It need to buy O state, not T6. you had better to weld aluminum tube by 1060 O-state, other types of tube is hard to spin.

● Different types of mild steel welding or seamless tube spinning performance is similar.

● The grade of the raw material for stainless steel welded pipes must be 304DDQ; otherwise, the weld seam will crack.

● Why hand welding make the tube is easy to break up in the welding position, because hand welding welding are uneven, the heat is unstable, and the metal spinning will crack in the weak strength area of the weld seam. It is best to use automatic straight seam welding. For stainless steel welding, Panasonic welding machines should be selected. OTC welding is selected for aluminum welding.

2. Metal spinning tolerance ＞

Many engineering designers and quality inspectors have problems with the precision design or inspection of spinning at the very beginning. They don’t know what the diameter tolerance metal spinning can meet , and how to inspect the metal spun product. Although spinning is also a CNC machine, the spun products are thin-walled parts. Due to the influence of stress rebound and structural strength, the edges of the products will become elliptical.

● About tolerance design : Many designer think the metal spinning tolerance can meet 0.1mm, actual tolerance is hard to meet, the diameter tolerance can meet +-0.3mm, but the perimeter tolerance can meet +-0.1mm, even the diameter is oval, but metal spinning product is soft, it also can be Installed the matching parts.

● About the tolerance inspection : Many quality inspectors use calipers to measure spun products, but this method is inaccurate because the mouth of the spun product is round and elliptical. When you apply a little force, the caliper will cause the spun product to deform again. The best approach is to make a pass and stop gauge to actually install the spun product. The accuracy of the perimeter of the spun product is generally quite good and can reach 0.2mm.

● Metal spun product assembly accuracy : such as metal spun product diameter accuracy +0.1-0.3mm, the mating parts accuracy design +0.01-0.01mm, the metal spun diameter = mating part + gap (0.1mm), if the gap value is less than 0.1mm, it is hard to assemble the metal spun product into the mating part.

3. Can the precision of spinning part be improved through CNC turning

Many mechanical designers may come up with a method of making the thickness of the spun product a little thicker and then turning it thinner on a lathe. In this way, the diameter accuracy of the spun product can be improved.

In fact, this idea is wrong. The poor precision of the spun products is not due to the insufficient precision of the spinning machine. Besides, the spinning machine can be equipped with turning tool to achieve the function of turning. The main reason for the poor precision of spinning is that after the spinning product undergoes cold extrusion, the internal stress inside the spinning is very large. But the spinning product is a thin-walled part with relatively low structural strength, the internal stress will cause the spinning product to deform.

If you want to achieve the higher precision, you need to use heat treatment to remove the internal stress, then design a fixture to fix the metal spinning to improve the structural strength. Otherwise, the spun products are prone to tool vibration during CNC turning or milling.

4. Does metal spinning needs mold

Many laymen are curious whether spinning requires molds for processing. When evaluating the plan and cost, molds are a very important expense. Each spun product requires a mold (Die ). Whether it is sheet spinning or tube spinning, the metal spinning machine needs a mold (Die) or fixture to fix the blank on spindle and rotate with it, so that it can be formed.