Skiving machine

Skiving or scarfing machines cut material off moving strips, usually metal, but also leather or laminates, to leave a desired edge shape or cross section. The process is used instead of rolling the material to shape when the material must not be work hardened, or must not shed minute slivers of metal later which is common in cold rolling processes.

The process involves moving the strip past precision-profiled slotted tools made to an exact shape, or past plain cutting tools. The tools are all usually made of tungsten carbide-based compounds. In early machines, it was necessary to precisely position the strip relative to the cutting tools, but newer machines use a floating suspension technology which enables tools to locate by material contact. This allows mutual initial positioning differences up to 12 mm or so followed by resilient automatic engagement. Products using this technology directly are automotive seatbelt springs, large power transformer winding strip, rotagravure plates, cable and hose clamps, gas tank straps, window counterbalance springs. Products using the process indirectly are tubes and pipe mills where the edge of the strip is accurately bevelled prior to being folded into tubular form and seam welded. The finished edges enable pinhole free welds.

For lines which use weld processes needing low speeds, such as laser welding, the skiving tools cannot normally cut - for example at speeds below metal planing speeds or about 10 meters/minute. In these cases the tools can be vibrated at high frequency to artificially increase the relative speed between the tools and strip.

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Skiving or Skivetek is also used for the manufacturing of heat sinks for pc cooling products. A pc cooler created with the use of skiving has the benefit that the heat sink base and the heat sink fins are created from one pieces of material (copper or aluminum). This provides optimal dissipation and transfer of the heat from the base to the fins. Additionally, the skiving process also increases the roughness of the heat-sink's fins. Unlike the underside of a heat-sink which needs to be smooth for maximum surface area contact with the heat-source that it cools, the fins benefit from this roughness because it increases the fins' surface area which serves to provide more area on which to release heat into the ambient environment.

References

* [http://www.patentstorm.us/patents/5761947-description.html Skiving machine patent]
* [http://www.princetonimaging.com/library/mechanical-dictionary/idxL.html Knight's 1880 Mechanical Dictionary]
* [http://www.thefabricator.com/Articles/Printer_Friendly_Article.cfm?ID=625 The little-known life of the scarfing tool]