Form turning aluminum tube

V

Vishwarath

Plastic

Joined

Mar 10, 2014

Location

New Delhi, India

• Mar 30, 2014

• #1

We are in the process of form turning Aluminum tube on a lathe. The purpose is to reduce the end cross section of the tube from OD 12.5mm to dia 10mm for 30mm at one end. The tube thickness is 1.25mm through out. Drawing is attached. For this, the tool is placed just at the Bottom dead centre of w/p and progressively 'fed' transversely in three-four passes. We find some shape inconsistencies in this process. What should be the speed and nature of the tool to be used.?

 

L

Long Tom

Stainless

Joined

Aug 21, 2011

Location

Fiddlefart, Oregon

• Mar 31, 2014

• #2

If I'm reading you right, a cutoff tool achieves your purpose. 12.50 mm OD reduced to 10 mm OD with a 1.250 wall thickness = nothing left.

 

Z

Zonko

Stainless

Joined

Aug 20, 2011

Location

Northern Germany

• Mar 31, 2014

• #3

If you look at the drawing the ID is supposed to "shrink" with the OD.

OD - ID

12.8 - 10.5
down to ->
10.2 - 8.2

Looks to me as if you would need to size the tube first. Id probably try mounting two smooth rollers in my knurling caliper and size the tube down to nominal. That Aluminum better be soft...
Drill the ID if it got too small.

The person who designed this part deserves to get his/her butt whipped....

 

L

L Vanice

Diamond

Joined

Feb 8, 2006

Location

Fort Wayne, IN

• Mar 31, 2014

• #4

Vishwarath said:

View attachment 103659We are in the process of form turning Aluminum tube on a lathe. The purpose is to reduce the end cross section of the tube from OD 12.5mm to dia 10mm for 30mm at one end. The tube thickness is 1.25mm through out. Drawing is attached. For this, the tool is placed just at the Bottom dead centre of w/p and progressively 'fed' transversely in three-four passes. We find some shape inconsistencies in this process. What should be the speed and nature of the tool to be used.?

Click to expand...

The drawing dimensions do not match the dimensions written in the question. The drawing does not show details of the inner diameter, in particular the location and shape of the transition from the large to the small inner diameter, so the part cannot be made, even by drilling solid bar. I have to wonder if this is some sort of school test question written by a person lacking practical knowledge. If a real part, the small end would have to be swaged before turning down.

Larry

 

D

Dr. Rob

Hot Rolled

Joined

Nov 25, 2002

Location

Sweden

• Mar 31, 2014

• #5

I don't know what those ^ guys mean, but i have done this before, with a single ball bearing roller tool on a manual lathe. Like Zonko said, two bearings in a pinch tool would be better.

I wonder if it would do better with a mandrel inside.

Enlisting a tube swaging place would be best of all.

.

 

Don Clement

Cast Iron

Joined

Jan 26, 2001

Location

Running Springs, Ca. USA

• Apr 1, 2014

• #6

I have been considering doing a similar thing in making tapered ends to aluminum tubing in the lathe. My untried approach was to use smooth rollers replacing the knurls in a scissor type knurling tool.

Don Clement

 

D

DDoug

Diamond

Joined

Oct 18, 2005

Location

NW Pa

• Apr 1, 2014

• #7

L&S (yes, Lodge and Shipley)

Floturn machine.

 

S

stephen thomas

Diamond

Joined

Jun 3, 2001

Location

downhill from Twain\'s study outside Elmira, NY

• Apr 1, 2014

• #8

For the naysayers up above & the description of process, it might be a not totally unreasonable guess that the OP is just making "snap together" tubing sections. Perfectly reasonable.

Can't personally comment on best approach.

smt

 

starbolin

Stainless

Joined

Mar 8, 2007

Location

Far Northern California, USA

• Apr 1, 2014

• #9

Are you using opposing tools or trying to do this with one tool? Are you using lubricant? Are you using a mandrel? The process can be sensitive to material. Do some batches of material draw down better than others? What is the grade of aluminum? Have you tried a better grade? Is your stock running true? Are you holding the stock in a collet? Is the collet hole clean and round? Is this and automatic machine or are you hand feeding?

The cold drawing process is very sensitive to speed. Speed helps the material self heat and flow. Too much heat and the material will gall and tear. You will just have to try different speeds to see what works best.

 

scadvice

Titanium

Joined

Jan 16, 2009

Location

"Stuck in Lodi", Ca

• Apr 1, 2014

• #10

Post more then ten times on various subjects and I'll tell you how to do it.

Starbolin has pretty much covered it...

 

V

Vishwarath

Plastic

Joined

Mar 10, 2014

Location

New Delhi, India

• Jun 30, 2014

• #11

Sir,
I am using a lathe to achieve the reduction in diameter at the end. How is it possible to use a cut off toll in this case?

 

V

Vishwarath

Plastic

Joined

Mar 10, 2014

Location

New Delhi, India

• Jun 30, 2014

• #12

Sir,
Thanks for you reply. You think I could be able to do the above process by setting the said tool onto the lathe machine?

 

V

Vishwarath

Plastic

Joined

Mar 10, 2014

Location

New Delhi, India

• Jun 30, 2014

• #13

Yes Sir,
I am trying to make pieces of the same that fit into each each other-back to back; Much like the foldable walking cane used by the blind.

 

V

Vishwarath

Plastic

Joined

Mar 10, 2014

Location

New Delhi, India

• Jun 30, 2014

• #14

Thank you Sir,
Please reply to this post http://www.practicalmachinist.com/v...-thinning-during-spinning-287337/#post2324338