Metal spinning path and fabrication parameter

Metal spinning fabrication parameter is very important to debug spun products ,we need to set different parameter according to different metal sheet and product shape ,the fabrication parameter includes metal spinning path, gap ,feed speed ,spindle speed,tail cylinder pressure .every parameter will effect the result of metal spinning forming ,we will instruct these parameters in this page .

CNC spinning path

This image shows the cylinder multipass conventional metal spinning path ,the blank metal sheet will deform according to every single path, it includes go path , back path, finish path .

● Go path : main function is to change the shape gradually to form cylinder .

● Back path : main function to increase the thickness ,keep the Path base hold the spun mold tightly ,to reduce the gap between blank and mold .if the gap is too big and the thickness will reduce ,it will break quickly .

● Finnish path : when the shape is finished forming, we will use the last path called finish path to make the surface and precision better .

● Path radius : bigger path radius easy to form corrugation of blank edge ,corrugation can cause the crevasse; little path radius can reduce the thickness quickly ,thickness is too thin can cause the break .you need to choose the suitable path radius to overcome the corrugation and thickness thinning is important for spinning forming .

● Roller radius : the spinning forming effect is same with path radius. aluminum conventional spinning choose R10-14, stainless steel choose R6-10.

● Gap : gap is the distance between roller and mold  ,if it is too little ,it bring to bigger resistance force and the exterior surface will have many none uniform lines compare to normal ; if it is too big, the internal surface can not be pressed to the mold ,the internal surface will be not smooth and it is easy to break in the spinning .

Maybe you will be confused how to judge the right gap ,except the internal and exterior surface, we can use a little hammer to hit the position of path base ,the sound of bigger gap is louder.

● Spindle speed : finish path will need faster speed than go and back path; bigger diameter metal spinning needs less spindle speed than little diameter; right and high speed can improve the surface quality . Hard metal needs less speed than soft metal,to reduce the spindle speed can increase the spinning force .

● Hydraulic pressure : it offer the frictionall force make the sheet spin with the spindle .Less pressure will cause relative rotation of sheet and the bottom of spun product will be scratches after finishing spinning .more pressure will reduce the bearings life of spindle and tailstock cylinder.

Metal spinning path of CNC program 

Metal spinning path is most important factor ,different metal spinner will have their metal spinning path to form ,but there is some common technical feature that you need to know .we can class these metal spinning path according to the different shape ,so we can understand it easily .

● Cylinder

Conventional spinning : Cylinder is multipass conventional spinning ,the deformation angle between cylinder and sheet is 90º, it spun many times because of big deformation angle . conventional spinning includes pressing deformation and stretch deformation .if some position is over the ductility of metal ,it will break in this position ,so you need to reduce the strength forming( increase the spinning roller radius and path radius) . The thinning rate of cylinder is bigger than other shape.

● Cone

Shear spinning : If the shear angel of cone ＞ 20º, it can be made by shear spinning ,the metal spinning path a single path that is along the interior curve of mold to form the spun product .

Thickness after spinning = blank thickness * sin A

● Trumpet

Trumpet metal spinning path includes shear spinning and multipass conventional spinning

The difference: the biggest diameter of multipass conventional spinning path of trumpet is less than half diameter of blank .

● Sphere

Sphere metal spinning path includes shear spinning and multipass conventional spinning .

Shear spinning : it can spin from Point 1 to Point 2 by shear spinning ,the shear angled of point 2 ＞ 25-30º,The thickness will reduce gradually from Point 1 to Point 2. the thickness of Point 2 is least .

Multipass conventional spinning : the thickness is uniform

● Complex shape 

Most of compete shape is made up by the shape of cone , cylinder ,trumpet and sphere .if you understand the spinning path above ,you can combine the different spinning path together .

● Necking spinning and tube spinning

Necking spinning is simple and similar with tube spinning ,the most important factor is keep the blank can be held tightly by mold or fixturing, the spinning path is regularly to form along the exterior curve of spun part .

If the necking height is too long ,you can use spin it by several section to improve the strength of the blank sheet .