Mandrel Bent Exhaust Systems

Vehicle Exhaust Quote

Vehicle Exhaust Quote
Mandrels
A mandrel is a steel rod or linked ball inserted into the tube while it is being bent to give the tube extra support to reduce wrinkling and breaking the tube during this process. The different types of mandrels are as follows.

Plug mandrel, a solid rod used on normal bends.
Form mandrel, a solid rod with curved end used on bend when more support is need.
Ball mandrel without cable, unlinked steel ball bearings inserted into tube, used on critical and precise bends.
Ball mandrel with cable, linked ball bearings inserted into tube, used on critical bend and precise bends.
Sand, sand packed into tube.
In production of a product where the bend is not critical a plug mandrel can be used. A form type tapers the end of the mandrel to provide more support in the bend of the tube. When precise bending is needed a ball mandrel (or ball mandrel with steel cable) should be used. The conjoined ball-like disks are inserted into the tubing to allow for bending while maintaining the same diameter throughout. Other styles include using sand, cerrobend, or frozen water. These allow for a somewhat constant diameter while providing an inexpensive alternative to the aforementioned styles.

Performance automotive or motorcycle exhaust pipe is a common application for a mandrel.

Bending springs
These are strong but flexible springs inserted into a pipe to support the pipe walls during manual bending. They have diameters only slightly less than the internal diameter of the pipe to be bent. They are only suitable for bending 15-and-22 mm (0.6-and-0.9 in) soft copper pipe (typically used in household plumbing) or PVC pipe.

The spring is pushed into the pipe until its center is roughly where the bend is to be. A length of flexible wire can be attached to the end of the spring to facilitate its removal. The pipe is generally held against the flexed knee, and the ends of the pipe are pulled up to create the bend. To make it easier to retrieve the spring from the pipe, it is a good idea to bend the pipe slightly more than required, and then slacken it off a little. They are less cumbersome than rotary benders, but are not suitable for bending short lengths of piping when it is difficult to get the required leverage on the pipe ends.

Bending springs for smaller diameter pipes (10?mm copper pipe) slide over the pipe instead of inside.