The thinning and stretching of the extrados of the tube while under the force of the bend forming process. If the elongating force exceeds the elastic limit of the tubing material, the tube will split or tear. Normally the elongation of tube is specified as a percentage of its original length.
FREE Tube-Bending Guide Download:
A complete guide to the principles of the 4-Step set-up for tube-bending tools
This is a printable handbook showing how to implement in four standardized steps the “forward mandrel” set-up for rotary-draw tube-bending machines and establish process control over the so-called black art. The procedure is based upon the guiding principle that the tools make the bend and takes advantage of the inserted design of modern mandrel tooling.