All MetalShaping

Go Back   All MetalShaping > General Metal Shaping Discussion > General Discussion
  Today's Posts Posts for Last 7 Days Posts for Last 14 Days  

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 10-30-2012, 08:14 PM
angus100 angus100 is offline
Member
 
Join Date: Oct 2012
Location: United Kingdom
Posts: 9
Default Aluminium brazing questions

Hi everyone,
I'm hoping someone can give me some advice on the best material and method for brazing aluminium. I'm wanting to fit some aluminium tanks (which can fairly easily be panel beaten as they're quite shallow) to a commercially obtained, packed construction radiator core, which will come with header plates. Most radiator companies here in UK use tig to fit the tanks but this is not as neat as the original method of construction which I believe was aluminium brazing done in a salt bath.
What is the best method and materials to use in absence of the flux in gas system? I would like to use something that is not a lot harder than the base does not go black as it ages and flows reasonably well to produce a neat job.
I should point out that although I have plenty of experience in gas welding steel, I don't have much experience in either welding or brazing ally.

Your help appreciated.

Gus
__________________
Angus McKenzie
Reply With Quote
  #2  
Old 10-30-2012, 09:34 PM
scranm scranm is offline
Member
 
Join Date: Jun 2009
Location: Indiana
Posts: 289
Default

http://www.harrisproductsgroup.com/e...raze-1070.aspx
__________________
Mark
Reply With Quote
  #3  
Old 10-30-2012, 10:12 PM
angus100 angus100 is offline
Member
 
Join Date: Oct 2012
Location: United Kingdom
Posts: 9
Default ally brazing alloy

Hey thanks Mark,
It seems just the stuff. Have you used it and how successfully?
gus.
__________________
Angus McKenzie
Reply With Quote
  #4  
Old 10-30-2012, 10:17 PM
Joe Hartson's Avatar
Joe Hartson Joe Hartson is offline
Administrator
 
Join Date: May 2009
Location: Pass Christian, MS
Posts: 4,981
Default

When aluminum is referred to as being brazed it is not the same as what you normally think of as brazing on steel and other materials. Aluminum radiators, evaporator core and similar type products are made they are referred to as being brazed. Actually the process uses a special alloy sheet called brazing sheet. The brazing sheet is actually two different alloys that are sandwiched together. A low melting temperature alloy is rolled on each side of a different higher melting temperature alloy. The outside alloy is very thin compared to the inner alloy. The inner alloy provides the strength and the outer alloy is melted together in a controlled, usually vacuum, environment.

Parts are stamped to the desired shape and then assembled to form the product being produced and the assembly is clamped together under a specific amount of force. The assembly is then placed in a vacuum brazing unit and heated to a specific temperature so that the only the outer layer of the brazing sheet melts. The outer layers flow together and when cooled the assembly is not one piece.

The outer lay of the brazing sheet is very corrosive resistant.

I am not aware of a salt bath being used for any brazing process of aluminum. Salt baths are use during aluminum recover during recycling. The salt bath keeps oxygen away for the molten aluminum and reduces the remelt loss and oxidation of the aluminum.

If you are not careful when you TIG weld on brazing sheet you can get a surface that will be less corrosive resistant than a totally vacuum brazed product. In some applications this is not important and is acceptable in others it is not acceptable and will lead to failure.

As a side note the reject rate in the rolling mill for brazing sheet is higher than with other rolled products. That is the nature of the beast and the reason very few mill will even roll it.

Hope this helps you understand the aluminum brazing process.
__________________
Joe Hartson

There is more than one way to go to town and they are all correct.
Reply With Quote
  #5  
Old 10-31-2012, 05:29 PM
angus100 angus100 is offline
Member
 
Join Date: Oct 2012
Location: United Kingdom
Posts: 9
Default Dip brazing

Thanks for your observations Joe. You say

I am not aware of a salt bath being used for any brazing process of aluminum. Salt baths are use during aluminum recover during recycling.

The salt bath keeps oxygen away for the molten aluminum and reduces the remelt loss and oxidation of the aluminum.

Well in just the same way salt baths ( ie flux baths) are indeed used for aluminium brazing to control oxidation - and have been for a long time. The filler rod is prepositioned and flows into the joints as the temperature is raised to a very precise figure. Its also called dip brazing. But of course its not something one can easily try at home!

Gus.


__________________
Angus McKenzie
Reply With Quote
  #6  
Old 11-01-2012, 10:14 PM
scranm scranm is offline
Member
 
Join Date: Jun 2009
Location: Indiana
Posts: 289
Default

Anything that the Harris corp makes is very good. I know a rep for the company so if you need more detailed info I can pass on his contact info. I have seen a demo of this product and it looks very good. Some companies relabel their products and sell as their own.


Quote:
Originally Posted by angus100 View Post
Hey thanks Mark,
It seems just the stuff. Have you used it and how successfully?
gus.
__________________
Mark
Reply With Quote
  #7  
Old 11-06-2012, 11:04 AM
jag2be's Avatar
jag2be jag2be is offline
Member
 
Join Date: Sep 2009
Location: Belgium
Posts: 170
Default

Hi,

Maybe this can help you?
http://www.techno-weld.biz/#!video
http://www.techno-weld.co.uk/home.html
__________________
Nico
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

All times are GMT -5. The time now is 06:48 PM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.