Metal spinning

Metal forming process of sheet metals using LATHE.

1. Metal Spinning

2. Metal Spinning Spinning is a sheet metal forming of parts over a rotating mandrel using rollers. It is used for axis symmetric products. It uses a Lathe, Mandrel (die), Tailstock and Rollers(tool). It may be either manual or computer controlled.

3. Basic parts of spinning machine Mandrel Tail Stock Head Stock Spindle Clamp Forming tools Work piece

4. Types Three basic types: Conventional spinning Shear spinning Tube spinning On basis of working Temperature: Hot Spinning Cold Spinning

5. CONVENTIONAL SPINNING A conventional spinning is a cold forming process in which the blank metal appears to flow somewhat like a piece of clay on a potter’s wheel. A conventional spinning has a circular blank of flat or preformed sheet metal is placed and held against a mandrel and rotated while a rigid tool deforms and shape the material over the mandrel.

6. We have a metal or cylinder, which is rotated at high speed on CNC lathe or on hands by using specially designed tools due to this we get the axially symmetric product . The tools used in this process can be controlled by two ways; Manual spinning Power spinning

7. Spinning tools or spinning rollers are forced against the rotating blank either by hand or by auxiliary power or both. Employing a series of axial and radial strokes ,the blank is spun onto the mandrel causing the metal to flow to the shape of the desired part.

8. CONVENTIONAL SPINNING

9. Tube Spinning In tube spinning, the thickness of hollow, cylindrical blanks is reduced or shaped by spinning them on a solid, round mandrel. The reduction in wall thickness results in a longer tube. This operation may be carried out externally or internally. The parts may be spun forward or backward.

10. Forward Tube Spinning Solid Mandrel Metal is spun over the mandrel externally. External Finishing is obtained. Eg : Tubes.

11. Backward Tube Spinning Hollow Mandrel Metal is spun inside the hollow mandrel. Internal Finishing is obtained.

12. Applications of Tube Spinning Tube spinning can be used to make Rocket Missile Pressure vessels Automotive components, such as car and truck Wheels.

13. Shear Spinning Shear spinning , also referred as  shear forming is similar to  conventional metal spinning. Shear spinning  the diameter of the final piece is approximately equal to that of the flat sheet metal blank .  The wall thickness is maintained by controlling the gap between the roller and the mandrel . In  shear forming  a reduction of the wall thickness occurs.

14. Shear Spinning  A sheet metal blank is placed between the mandrel and the tailstock of the spinning machine. The mandrel has the interior shape of the desired final component .  A roller makes the sheet metal wrap the mandrel so that it takes its shape . As can be seen, s1 which is the initial wall thickness of the work piece is reduced to s0.

15. Shear Spinning A shear forming machine will look very much like a conventional spinning machine , except for that it has to be much more robust to withstand the higher forces necessary to perform the shearing operation . The design of the roller must be considered carefully, because it affects the shape of the component, the wall thickness, and dimensional accuracy. 

16. Difference between Conventional and Shear Spinning Conventional Spinning Shear Spinning No reduction in Thickness. Thickness is reduced. Simple tool and Machinery is adequate Heavy machinery and tooling is required due to the application if heavy forces. Same physical properties as work piece. Physical property enhances.

17. Hot Spinning Hot spinning, the metal blank is heated to forging temperature and then forming it into the desired shape. A Roller is used which contacts the surface of the rotating part and causes the flow of metal over the form mandrel. This method is generally used for thicker plates and sheets, which do not plastically de-formed at room temperature.

18. Merits and De-merits of Hot Spinning Larger deformation can be accomplished and more rapidly by hot working since the metal is in plastic state. Grain structure of the metal is refined and physical properties improved. Due to high temperature a rapid oxidation takes place. It involves excessive expenditure on account of high cost of tooling.

19. Cold Spinning Cold spinning process is similar to hot spinning except that the metal blank is worked at room temperature. This method is generally best suited for thin plates and sheets of aluminum and other soft metals . Examples : light reflectors, cooking utensils, liquid containers, radial engine cowling, domestic use hollow parts etc.

20. Cold Spinning Cold Spinning Lathe

21. Merits and De-merits of Cold Spinning Surface finish of the component is better because no oxidation takes place during the process. It is an ideal method for increasing hardness of those metals which do not respond to the heat treatment. Only ductile metals can be shaped through cold spinning. Subsequent heat treatment is mostly needed to remove the residual stresses set up during cold working.

22. Tools and Equipments Mandrel : It is a block over which the sheet metal blank is formed. It is made of wood, steel alloys or polymers. Rollers : Used to force the sheet metal against the mandrel. It uses a ball roller to reduce friction, heating and wearing of tool and smooth surface finish. Cutting tools : Cutting of the extrusions or extra metal is done using a handheld tool with Tool steel tip or Carbide tip as cutting material.

23. Tools and Equipments Lubricants : Lubricants are essential in all metal spinning operations. Facilitates easy removal of the part from the mandrel. Help improve surface finish. Commonly used lubricants : wax , tallows , soaps and grease. Machines : Mostly lathe based machines ( both conventional and CNC-based) are employed for spinning operation. Most modern machines used for spinning are semi –automated. Metal spinning machines can be both vertical or horizontal.

24. Tools and Equipments

25. Applications The following are examples of products that can be manufactured by metal spinning: Baskets, basins and bowls. Hoppers and kettles. Nozzles, venturis and tank outlets. Cones and cups. Funnels, cylinders, domes and drums. Rings, hemispheres and shells. Materials that can be spun : Copper, Brass, Aluminium , Stainless Steel, Sheet Metal.

26. Applications Automobile application : Vacuum booster used in braking system.

27. Merits The tooling costs and capital investments are relatively small. Design changes in the work piece can be accommodated at relatively low costs. Since there is no removal of metal, there is no material wastage and the process is economical. It is a chip less process. Can be easily automated and as well as high production rates can be achieved. Spun parts usually have high tensile strength and can be used for high pressure applications. eg . Scuba driving tanks.

28. De-merits Manual metal spinning is usually significantly slower than press forging. Deformation loads allowable are much lower in metal spinning than in press forging. Requirement of highly trained operators in manual spinning process.

29. Conclusion Spinning is forming of axis-symmetrical products over a mandrel. It is similar to that of forming clay on a potter’s wheel . Three types Conventional spinning Shear spinning Tube spinning Can be both Hot worked and Cold worked . Machine used is LATHE . Process can be either manual or can be automated . Less expensive and various applications.

30. References Serope Kalpakjian and Steven R. Schmid . Manufacturing Processes for Engineering Materials. 2015 http://www.smartclima.com/metal-spinning-fabrication.htm Debapriya M. Spinning of Metals: Process, Advantages and Uses . Retrieved from http://www.yourarticlelibrary.com/metallurgy/spinning-of-metals-process-advantages-and-uses