Mild steel or DOM?
Full Member
Joined: Dec 2001
Posts: 189
Likes: 0
From: St. Louis
DOM is to mild steel as sliced is to bread.
Its how the tube is made. There are two major kinds of roll cage tube DOM (drawn over mandrel) and ERW (electrical resistance welded). ERW is made by rolling up a rectangular piece of steel and welding the seam. DOM is made by magic.
Anyway, DOM is much stronger than ERW, no seam = no stress risers. For SCCA racing you can typically run smaller diameter, lighter, DOM than ERW. The only advantage of ERW is that it is cheaper.
Alternately you might ask about mild steel vs. chromoly alloy. In which case you can run lighter yet alloy cages, but the welding is tricky and REQUIRES heat treat after welding, so very few people do this.
I recomment mild steel, DOM, installed with tight joints and welded by a skilled operator.
Steven
Its how the tube is made. There are two major kinds of roll cage tube DOM (drawn over mandrel) and ERW (electrical resistance welded). ERW is made by rolling up a rectangular piece of steel and welding the seam. DOM is made by magic.
Anyway, DOM is much stronger than ERW, no seam = no stress risers. For SCCA racing you can typically run smaller diameter, lighter, DOM than ERW. The only advantage of ERW is that it is cheaper.
Alternately you might ask about mild steel vs. chromoly alloy. In which case you can run lighter yet alloy cages, but the welding is tricky and REQUIRES heat treat after welding, so very few people do this.
I recomment mild steel, DOM, installed with tight joints and welded by a skilled operator.
Steven
Rotorhead
Joined: Feb 2001
Posts: 9,136
Likes: 39
From: Charlottesville, Virginia, USA
Senior Member
Joined: Nov 2001
Posts: 576
Likes: 0
From: Rochester NY
Well actuually DOM is made just like ERW. DOM stands for "drawn over mandrel" Essentially it is a suplimental prosses that erases the stress risers from the ERW process. It is also held to higher tolerances and a more pure alloy. BTW rules have changed for 2003 and I don't have the book infront of me here but I don't think ERW tube will be legal shortly. I use 1.5 or 1.75 DOM for all of my cages. Mig welded with a Lincoln 255.
Thread Starter
Senior Member
Joined: Dec 2002
Posts: 317
Likes: 1
From: Fairless Hills,PA
Yeah for 2003 ERW is not legal. I know about metals i work in a machine shop just wasnt sure if ppl used ERW. The guy thats bending up my cage is making it out of 1.750 DOM. Then I'm goin to mig weld it in. A year of welding at tech school comes in handy.
Airflow is my life
Joined: Aug 2002
Posts: 6,736
Likes: 2
From: Orlando, Fl
DOM is NOT made like ERW. Drawn Over Mandrel tubing starts as a bar stock shape metal. It is then physically drawn over a mandrel that forms it into a tube shape. If you dont know what DOM is please dont comment on how its made.
