Depending on length, roll forming length tolerance of plus or minus 0.020 to 0.093 of an inch, or 0.51 to 0.236 of a millimetre are possible. To determine straightness few terms are used and camber being one of m. Camber means deviation a side edge from a straight line measured prior to roll forming.

The die used in electromagnetic process should be made of low electrical conductivity to minimize magnetic cushion effect. Dies are generally made of steel or epoxy resin.

Macro-emulsions contain an oil-based lubricant, such as a mineral or compounded oil in form of suspended droplets, which have been dispersed with emulsifiers due to which y become milky white appearance. Therefore, y are sometimes misleadingly called soluble oils.

In EMF process, eddy currents are induced in workpiece which is placed close to coil. When se eddy currents interact with magnetic field, cause mutual repulsion between workpiece and forming coil due to which workpiece is stressed beyond its yield strength, resulting in permanent deformation.

Waviness or unevenness at edges can be avoided by incorporating a flange, hem, or rib near or at edge. Longitudinal stiffening ribs are used to minimize irregularity in areas of product.

The stock to be roll formed may be eir pre-cut to a pre-determined length before roll forming, or post-cut afterward to a specified dimension. But latter one is most common. By incorporating auxiliary equipment such as pre-notching, punching, embossing, etc. post-cut method can be a complete net-shape process, fully automated.

In EMF, material is loaded into its plastic region, resulting in permanent deformation, so that springback associated with mechanical processes is vertually eliminated because re is no mechanical contact.

Here, h = 1in; number of passes = 4 and each of length = 14in
Therefore, l = 4 * 14 = 56.

Therefore,
Elongation, e = (56.022 – 56)/ 56
= 0.0004 = 0.04%.

ISO grade 460 (SAE 140) Gear oil is used in sealed gearboxes. Gear oil has extreme pressure additives that strengn non-detergent oils to withstand heavy loads found in gears and gear drive systems.

?Too quick? forming (too few passes) will distort product because of unacceptable level of stresses generated in metal. On or hand, too many passes will make tooling and process uneconomical.