EoW January 2013

Focus on

▲ ▲ PlasmaAnnealer for high speed annealing of stainless steel and nickel alloy wire

High-speed alternative for continuous annealing Wire, rope and tubes made of stainless steel and nickel alloys have so far been annealed predominantly in tube or radiance furnaces. Most traditional tube annealing furnaces operate in multiline configurations, due to their low production speed. Plasmait GmbH has introduced a second-generation plasma annealer designed for wire, rope and tubes made of stainless steel and nickel alloys and with cross-sections of up to 20mm 2 . With this new concept Plasmait allowed for an increase of continuous annealing speeds of stainless steels and nickel alloys. The slow speed of traditional tube furnaces means that the annealing of stainless steel and nickel alloy wires generally involves a multi-line set up. Multi-line process is logistically demanding and involves multiple payoffs and take-ups that can require substantial capital outlay. A multi-line annealing plant takes a large workshop space and locks considerable money in working capital related to the material being processed on each of the annealing lines. Furthermore, slow annealing speed means that the drawing or rolling processes have to be performed separately, off-line from annealing, which adds to the complexity of process logistics. The higher process speed of the new plasma annealer allows a single line plasma annealing plant to substitute multiple lines of a tube annealer, whilst retaining the same output capacity. In some cases it is also possible for the

Annealing controlled instantaneously and with a high degree of accuracy via power supply. This allows the operator to accurately target mechanical properties and provides greater flexibility in new product development. Ion bombardment or ion sputtering on the material surface results in removal of the upper surface layer. Dirty deposits, soaps, lubricants and fine oxides break under the ion bombardment in the plasma chamber. The debris and other cracked surface contamination are sucked out of the plasma chamber by the vacuum system and are filtered out through the exhaust installation. The dry surface cleaning and degreasing being performed simultaneously with plasma annealing is of particularly benefit to applications with demanding surface requirements in sectors such as medical, welding or aerospace. power is

plasma annealer to operate in-line with a drawing or a rolling machine. Plasma – an ionised gas – is maintained in the plasma chamber at low pressure. In the plasma chamber the electric field accelerates ions towards the surface of the processed material and electrons towards the outer wall of the chamber. Ion bombardment results in heating on the surface of the processed material. The electrons have virtually no mass and carry no energy, therefore do not heat the plasma chamber. This makes plasma annealing an efficient technique to heat the material, resulting in only a very small percentage of power being lost as dissipated heat in the plasma chamber. Rapid heating and reduced time of recrystallisation results in fine grain size. Small grain size with uniform crystal structure in the longitudinal and transversal direction improves materials’ susceptibility to cold working and resistance to surface cracking.

Plasmait GmbH – Austria Website : www.plasmait.com

Wires for the spring industry To service the spring industry in Switzerland and Austria, Hempel Wire Ltd has a range of EN10270-3 (1.4310) wires, 0.8 to 6mm, available for call off from stock in Dübendorf, Switzerland. The company has also established itself as a strategic partner for special grades such as 17/7Ph, X750, Duplex and Super Duplex, and with a production range of 0.8 to 18mm can satisfy most demands. As members of IST and UKSMA it can also assist with any technical queries. Hempel Wire Ltd, the specialist wire producer within the Hempel Special Metals Group, has moved production of profile wire in stainless and nickel-based alloys to a purpose built manufacturing facility in Rotherham, UK. Round and profiled wire production is now based at the same site. Hempel Special Metals AG – Switzerland Website : www.hempel-metals.com

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