1. Home
  2. ⏣ General Metalworking
  3. spin forming on air

spin forming on air

Hi

I need to build parabolic dishes of different shapes. I think that spin forming should be the ideal method but I no nothing about that method. I'm not a metal craftman.

I have some questions about that process.

The material I want to use is either cupper or aluminium. Thickness is in the order of 20-28 ga.

I don't want to make a mold for every dish because I won't produce many of each size & shape so it has to be "turned" on air.

Is spinning on air precise enough to produce an exact curve every time ?

What should be the rotation speed of the machine for let's say a 2-4 feetd dia. dish ?

Can I use a modified small lathe for that or a simple spindle could do the job ?

Thanks

Reply to
Bill
Loading thread data ...

Don't move.... The bright young men in their clean white coats are coming to take you away!

HaHa!

JR Dweller in the cellar

Bill wrote:

Reply to
JR North

You should google for metal spinning. There is also a yahoo group for metal spinners. Whenever I spin something the part of metal being "supported" by the air seems to almost always be conical. Sometimes I get a curved shape that may or not be parabolic. But then I'm not trying to get a particular shape in the air, I'm trying to get the metal to conform to the chuck and it will take whatever shape it wants from flat disc to fitting the chuck. Some production metal spinning is done on CNC machines. Maybe if the material was consistent a tool path could be programmed to get the desired shapes without too many scrap parts. ERS

Reply to
Eric R Snow

We specialize in metal spinning for more info:

formatting link
Daveb

Reply to
Anonymous

...

I went through your web site, watched your video, very interesting. Couple of questions. How are you quickly chucking the part? Tell me more about the tool that's contacting the metal to spin.

I doubt that I ever do it, but it looks like most CNC lathes could be easily modified for spinning, at least for HSM type runs.

Karl

Reply to
Karl Townsend

Reply to
David Billington

The part (disk) has a hole in the center that locates over a pin on the ejector and then the tailstock is closed.

Most machines have a centering device (hydraulic) the you set the disk on then it extends upwards and the tailstock is then closed.

The tool is just a heat treated steel with a radius and a relief with a bearing in the center.

When you do large diameters (as in the video) you see the backup roller that extends out on a cylinder and as the part is being spun is is pushbacked this is to keep the part from distorting or bottlecapping.

Here is a good video we made:

formatting link
Regards Daveb

Reply to
Anonymous

formatting link

Reply to
Anonymous

Aha! I've been puzzling over that one for a while, with mediocre results. I did a little bit of spinning on my wood lathe, and the "bottlecapping" made it seem impossible to do without making the disks really oversized and then cutting off the remainder. Am I interpreting the video correctly when it appears that the forming roller is mechanically pushing back the backup roller as it goes, or is that all computer controlled?

Thanks for the missing link!

Reply to
Prometheus

The part is pushing the backup roller, the pressure is adjustable.

Regards Daveb

Reply to
Anonymous

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.