Friction welding is also used to fuse together big pieces of steel.

One of the projects which I worked on was machinery that replaced the anodes used in aluminium smelters. Aluminium is made in enormous electrical furnaces and use carbon anodes. ( Aluminium smelter use more electricity than that of a small town). The anodes are basically big blocks of carbon 900 x 900 x 1000 – 1500mm long and mounted on a steel stem. The stem has a number of branches at the bottom which fit into holes in the carbon block. Molten cast iron is used as a filler for bonding them together (similar process to solderring but on a bigger scale).

The carbon is eventually eroded away and has to be replaced. The bottom of the support stems is cut off and new ones welded in place. The re-furbished stem is used again with a new carbon block.

New pieces are spun at speed and friction welded to the bottom of the spigots at the bottom of the support stem. These are 150 – 250mm diameter and welded in minutes.

Paul

Photo after the pouring of cast iron.

When at work part of the repair of mould tools used to be done by inserting apiece of steel without showing any Mark or scar on the finnished part but for the last few years we had the damage welded by laser welding and it made repairs so easy in comparison. The laser welder was a mobile unit and so in many cases we didn't have to to evan have to strip or dismantle the tool.

David

On a slightly different scale, one of the top welders where I used to work, cut a coke can open and made a flat sheet, then cut that in half, so he ended up with two pieces of al. alloy sheet about 150mm x 60mm x 0.2mm thick. He then welded to two sheets back together to form one piece about 150mm x 120mm x 0.2mm thick.

Well I was impressed!!

cheers

Bill