ponytug
Super Member
Yes, yes, and yes.
The general idea is that you want the heat sink material not to be weldable under the conditions that you are welding. Since aluminum has a low melting point, you want the aluminum to be thick and large to absorb the heat and conduct it away fast enough not to melt.
Copper has a higher density and better thermal conductivity. I have a pair of copper "spoons" made of thick walled copper pipe for starting and ending TIG welds and to back holes to keep air from penetrating the welding areas. You can get fairly heavy pieces at scrap yards by looking for copper bus bars. I have heard of people using brass, but I have never tried it.
Graphite has the highest "melting point". I find it trickier to use, but your mileage will vary...
You can, of course, use this the other way around, e.g. using stainless steel to back up aluminum.
All the best,
Peter
The general idea is that you want the heat sink material not to be weldable under the conditions that you are welding. Since aluminum has a low melting point, you want the aluminum to be thick and large to absorb the heat and conduct it away fast enough not to melt.
Copper has a higher density and better thermal conductivity. I have a pair of copper "spoons" made of thick walled copper pipe for starting and ending TIG welds and to back holes to keep air from penetrating the welding areas. You can get fairly heavy pieces at scrap yards by looking for copper bus bars. I have heard of people using brass, but I have never tried it.
Graphite has the highest "melting point". I find it trickier to use, but your mileage will vary...
You can, of course, use this the other way around, e.g. using stainless steel to back up aluminum.
All the best,
Peter
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