Working as a product sourcing specialist has it’s advantages but one thing I’m still trying to get my head around is the minimum quantities suppliers charge for their products or services. In relation to the frame on my camper, I need to source a company who can mandrel bend 50 x 50 x 2.5mm steel rectangular hollow section tubing (RHS) in mild steel. There is only 1 company in Perth who can perform this task and will only bend RHS with a minimum wall thickness of 3mm. Why? maybe it has something to do with retaining the structural strength of the frame. Anyway, the price is around $450 to perform 2 bends. This is because $450 is the minimum they will charge. To put this in perspective, a single bend is only $45 excl. of the ol’ Johnny Howard (GST) so effectively, I’ll be paying 5 times the going rate for a single bend… and to rub salt in the wound, the cost of the steel for the entire frame is a fraction of that. What to do???
So what is a Mandrel Bend?
A mandrel bend is simply a bend that maintains a consistent diameter throughout the bend. Mandrel bending is used where the inside radius of the tube must be bent without wrinkling or deformation. This is achieved by inserting a flexible or solid fixed “mandrel” to support the interior walls of a tube during the bending process. The walls are supported internally with either a flexible mandrel that bends with the tube, or a fixed “bullet” mandrel set internally at the pivot point of the radius die. Mandrel bends are commonly used in the manufacture of automobile exhaust pipes, turbocharger intake and outlet tubing, and custom exhaust systems. It can laso be performed on square of rectangular tube.
This is an example of mandrel bent rectangular hollow section tubing.