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Flanging Flanging is the process of bending the edges of the sheet metal at 90 degrees. Flanging is done to increase the stiffness or to join two sheet metal parts. (Elements of Manufacturing Processes, Parashar, p.275) Tube spinning Tube spinning is used to reduce the wall thickness and increase the length of a tube by means of a roller applied to the work over a cylindirical mandrel. Tube spinning is similar to shear spinning except that the starting workpiece is a tube rather than a flat disk. The operation can be performed by applying the roller against the work externally (using a cylindirical mandrel on the inside of the tube) or internally (using a die to surround the tube). It is also possible to form profiles in the walls of the cylinder, by controlling the path of the roller as it moves tangentially along the wall. (Fundamentals of Modern Manufacturing, 4th Edition, Groover, p.474) Stretch Forming In sheet metal bending operation, compressive stress is developed, which ultimately leads to local buckling or wrinkling. It can be avoided by keeping the sheet metal strip under tension during the operation. This process of simultaneous stretching and bending is called stretch forming. In stretch forming the complete deformation is carried out in plastic state only. The material is first brought into plastic state by stretching. Hence it is called stretch forming. (Production Technology, Narayana, p.220) Embossing The surfaces of extruded foam sheet and profile may not have the appropriate texture for some applications. Although embossed sheet is laminated to foam, the laminating process is fraught with technical issues. As an alternative, embossing rolls are used to impress a particular pattern or design into the foam. The foam is heated either with hot air or radiant heating. The embossing rolls are also heated and are usually coated with low friction polymers. (Thermoplastic Foam Extrusion, Throne, p.76)