AW: SER1 >> Spot welding aluminium

[prev] [thread] [next] [Date index for 2005/09/12]

Hi Tom,

I would not agree to the fact that cleaning the metal before welding will
improve the weld. The time between sanding or brushing the aluminium and
actually applying the welder is long enough for a new coat of aluminiumoxide
to build up again. You basically need too much time to correctly place the
parts to be welded. 

In my opinion it is rather a question of having sufficient amps available in
quite a short interval and apply sufficient pressure. If pressure is high
this will lead to a closer contact of the two components to be joined and
electrical resistance will be less than at the other areas of contact
between the two parts. The current at this spot will increase and create a
heat density sufficient to produce an acceptable spot.

For the cleaning, as done when oxy-acetylene welding aluminium it is
ablolutely imperative to use stainless steel brushes 

-----Ursprüngliche Nachricht-----
Von: series1-host@xxxxxxxxx.xxx [mailto:series1-host@xxxxxxxxx.xxx] Im
Auftrag von Tom Tollefson
Gesendet: Montag, 12. September 2005 14:14
An: series1@xxxxxxxxx.xxx
Betreff: RE: SER1 >> Spot welding aluminium



G'day Charlie

No (non corrosive!) flux necessary.
The ticket here is to clean the metal thoroughly before welding. What gives
Aluminium its corrosion resisting properties is a layer of Alu oxides on the
surface that develop as soon as it gets in contact with oxygen. This layer
needs to be removed (by sanding) just prior to welding. The oxide has a
melting point aprox. 4 times higher than the base metal itself and if not
removed will require a higher energy input which usually results in the base
metal melting away before a successful weld can be accomplished. This is
especially true if gas welding is employed.
The common failure to thoroughly "clean" the parts to be welded gives
Aluminium the untrue reputation of being "difficult" to weld, which it
actually isn't.

The "six P" rule applies here: Proper Preparation Prevents Piss Poor
Performance!

 Tom Tollefson
 Toronto,Canada
1952 Land Rover 80"


To change subscription see www.landrover.net/series1/mail



To change subscription see www.landrover.net/series1/mail