Metal spinning is a challenging and experienced work, it need time to learn to become a excellent metal spinning expert. There are too many metal spinning skills and mothods you need to know, such as deep drawing, shearing, flanging, necking, expanding, hemming.

1.How to analysis metal spinning performance of material

Metal spinning performance of the different material is basic knowledge of spin forming, you need to know the hardness, tensile strength, ductility is related to the metal spinning performance of material. The material ductility is good, the deep drawing ability is good and it is not easily break in the spinning. The hardness and tensile strength is high, it needs stronger spinning force to form, at the same time, the springback valve is bigger. If you know more about the materials performance, you can know what shape and accuracy of metal spun products can be made by this material.

There are many materials can be spun, the basic materials have aluminum, steel, stainless steel, copper, brass. Most of metal spinner know that aluminum, brass, copper (common materials＞＞) is soft with good ductility, it is good for metal spinning, when you spin the special or aerospace materials＞＞, you neeed to compare the properties of stainless steel 304 (SUS304) to analysis the metal spinning performance.

Tensile strength σb (MPa) - 480Mpa  

Yield strength σ0.2 (MPa) - 550

Hardness - 201HBW  

Elongation δ5 (%)≥40

If you want to know the metal spinning of the material that you have not known before, you can check the material in the Wikipedia, such as you search the Inconel 718, you find the parameter of the material.

Tensile strength σb (MPa) - 965Mpa  

Yield strengthσ0.2 (MPa) - 550  

Hardness ＜363HBW  

Elongation δ5 (%)≥30

Through comparison, You find the tensile and yield strength of Inconel 718 is about 2 times stainless steel 304, the hardness of inconel 718 is about 1.5 times of stainless steel 304, it proves that Inconel 718 needs 2 times of stainless steel spinning force and the springback of inconel 718 is bigger than SUS304. At last, you compare the elongation, you find SUS304 have better ductility than Inconel 718.

After we compare the properties of material based on stainless 304, you can choose the right CNC metal spinning that the spinning force is enough to spin this material, if the ductility is less than SUS304, you need to consider whether using the hot spinning.

2. Metal spinning roller ＞＞

You need to choose the right roller when you make a CNC metal spinning program.

① Roller material: roller has two materials, first kinds of roller is made by Cr12mov, it is quenching to improve the surface toughness of roller. Second kinds of roller is surface plating to improve the wear -resisting.

② Roller diameter : Dinnovation metal spinning have three specification of roller, the diameter is 80mm, 140mm, 180mm. The metal spinning product is less than 200mm, we choose the diameter 80mm roller, the metal spinning product is 200 - 500mm, we choose the diameter 140mm roller, the metal spinning product ＞500mm, we choose the diameter 180mm roller. Actually the metal spinning diameter is bigger, you can choose the bigger roller.

③Roller shape : common roller is symmetrical design, because when one side is scratched when it have been used for a long time, you can use the other side to spin, when two sides are scratched, you can polish the surface to achieve 4K mirror, it can be used again.

④Special roller : There is another roller to avoid the interference with mold when roller move according to CNC program. This is special metal spinning roller, you can the following image to know it.

3. Mold design and adjust

Many metal spinner all know metal spinning mold is simple, it don't like deep drawing mold have upper mold and lower mold. Even though design a metal spinning mold is simple, it still have some key knowledge you need to know. At first, mold hardness need higher than blank materials. Second, the exterior surface of mold must be smooth. Third, you need to reserve machining allowance of mold to adjust the accuracy when it has springback after spinning.

4. Tube fixture design

The most of important factor to make tube spinning is to control the suitable clamp force. If the clamp force is big, it can make tube transformation, if the clamp force is little, the tube will move when roller pull or press it. So design a right fixture is important for tube spinning, you have better to choose the hydraulic fixture, it works more stably. The metal spinning path and parameter is less effect compare to clamping fixture.

5. Thinning rate

Thinning rate is one of the metal spinning properties, the work piece will produce tensile and shear deformation that the position is touched by roller, but the bottom or the clamp position can maintain the original thickness of blank sheet. You need to know the basic principle of different shape how to thin in the spin processing, such as cylinder, cone, hemisphere, the shearing and conventional thinning rate is different. 

6. CAD metal spinning path drawing

Most of metal spinner know that CNC metal spinning path drawing is hardest work, it needs many years of experience. A experienced metal spinner or expert not only know how to design mold and choose right radius and types of roller, but also know how to draw right the path according to different material type and shape. Even though every metal spinner have different path to form, there are several basic metal spin forming principle you must know.

① Conventional spin form path

Metal spinning path is classified go path and back path, the function of go path is pull the workpiece, roller make the height longer and diameter smaller. The function of back path is press the workpiece on the mold and make it clamp the mold with less gap between workpiece and mold, More back path can make workpiece keep the original thickness.

Workpiece bottom break or workpiece edge crinkle : workpiece bottom break prove go path radius is too little, the pull thinning is too much, it need to increase the go path radius or increase the back path to keep workpiece clamp the mold tightly. If workpiece edge is crinkle in the thin conventional spinning, you can reduce the the go path radius or use the back roller to support the edge to improve the strength of workpiece.

② Roller gap 

Adjusting the right roller gap can keep the workpiece hold the mold tightly, the workpiece clamp mold more tightly, the thinning is more thick after spinning. If the gap is too big, the workpiece bottom will be break as the workpiece will be thinning quickly, if the gap is too little, the metal spinning will shake and the exterior will have shake line that is not uniform.  

More problem about metal spinning parameter and path ＞＞

③ Shearing spin forming path

Shearing spinning path is simpler than conventional spinning, it is most important to control the roller gap.

Common CNC metal spinning problems and solutions＞＞

7. The parameter of machine set  

There are main parameter set in the CNC programming. At first, spindle speed can choose 300-1200r/min, such as stainless steel or aluminum cone diameter is 300mm, you can choose spindle speed that aluminum is 300r/min and stainless steel is 600r/min, spindle speed is related to the hardness, diameter, thickness of blank sheet, the valve of these is bigger, spindle speed is less. Second, feed speed can choose 3000-6000mm/min when the diameter is less than 300mm, thick or hard can use the less feed speed, thin or soft can use the higher feed speed.  

8. Automatic programming software 

Using Automatic programming software can reduce the manual coding work of the metal spinner, it improve the working efficiency.

9. Mold and roller runout control

To control the mold and roller runout within 0.02mm, it is benefit for metal spinning accuracy,  to reduce the risk of break in the process.