TPi October 2009

developments products &

Copper alloys used to create tubes with a smooth surface

stainless steel sheet. Because of the potential cold welding effect caused by this difference in speed on the forming rolls, the rolls must be made from a material with excellent sliding characteristics, in order to obtain a perfect surface on the tubes. Ampco Metal’s patented alloy Ampco ® 25 offers multiple advantages, including the extended life of forming rolls and the quality of the finish to the stainless steel tubes it produces. Ampco 25 alloy requires no further heat-treatment or expensive coatings to give these results. Ampco 25 rolls are also used on the same production lines at the tube welding station, when producing mild steel tubes. The non-magnetic properties of Ampco 25 rolls at these welding stations provides another advantage, avoiding over-heating of the pressure rolls, due to induction from the high-frequency welding loop. For bending stainless steel or other tubular exhaust pipe materials, the family of Ampco 18, Ampco 21 and Ampco M4 alloys provide benefits for product quality and prolonged life of the production tooling. Ampco M4 used as mandrel and wiper dies in tube bending have been proven to last longer than commercial aluminium bronzes. Ampco M4 mandrels do not need hardening or expensive coatings, and the advantages for wiper dies are no galling or scratching, so no corrosion starting point.

AMPCOMetal provideshigh-technology alloys for demanding applications. The company’s comprehensive range of high-performance aluminium bronze alloys for pressings, tube bending, deep drawing, rolling and profiling applications are readily available. When producing stainless steel tubes from strip, it is possible that the tube surface can adhere to the roll surface,

(so called ‘cold welding’ or ‘galling’). As the roll turns, such cold welding causes damage to the surface of the stainless steel tube, resulting in higher rejection rates and lower productivity. Additionally, when working with a semi- circular forming roll in order to obtain a tube out of a flat stainless steel strip, any differences in tangential speeds along the surface of the tube will induce sliding between the forming roll and the

Ampco Metal SA – Switzerland info@ampcometal.com www.ampcometal.com

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Tube Products International October 2009

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