WCA January 2008

Welding – machinery and technology

Global support from LPWI

L & P Wire International (LPWI) is a wholly owned subsidiary of Leggett & Platt, Incorporated, a diversified manufacturer that conceives, designs and produces a broad variety of engineered components and products for customers worldwide. Using L&P’s global network of offices and production facilities, LPWI is able to source welding wire for supply to distributors and large end-users. The wire can be provided in the company’s own cartons or, as part of the inclusive package, LPWI is able to offer ‘own brand’ carton design at no extra cost.

L&P Wire International – UK Fax : +44 151 513 5887 Email : info@lpwire.com Website : www.lpwire.com

Sales director John Stanway

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Precision welders from Whitelegg Whitelegg Machines has been progressively producing CNC wire bending and welding machines since 1990. The CFM range has become well-known and highly valued by manufacturers of all types of products. The company’s success has enabled it to sell machines worldwide. The most recent development has been the adaptation to weld stainless steel wire. Until recently it was not possible to resistance weld stainless steel, or if welded, the weld has been so weak that it broke quite easily. Now, with Whitelegg’s new system, using inert gases, the steel flows as it is heated, giving a perfect weld without upset. The resultant weld strength is such that bend tests of 180º fail to break it! Companies specialising in stainless steel products have been quick to appreciate the advantage of a welded product coming off the machine at a rate of 10-12 per minute, whereas it was taking more than a minute to hand weld one component using a gas torch. This impressive production rate includes forming the component – for example a ring or rectangle – from the wire coil. Due to demand, the company has recently introduced a hand operated butt welding machine using the same controls and technology as the automatic machine, for wire up to 6mm diameter.

Buttwelding cutting wires When producing solar cells, a mono crystalline rod is drawn in continuous rotation out of the melted mass of high-purity silicon. For further processing, this rod is cut into a cuboid of about 50cm length and a lateral edge of about 30cm. These cuboids, called ‘ingots’, are sliced into thin sheets with high tensile carbon steel wires which is also used for steel breaker tyres. These steel wires ranging from 0.1mm to 0.16mm diameter come from a single spool, are deviated around wire guides and lead over the ingot once per cut. The principle is the one of an ‘egg cutter’. With a speed of about 12m/s the wire cuts the ingot in very thin slices from 0.28mm to 0.18mm. For this purpose, the wire goes through a liquid with tiny slurry (free abrasives) which enable the cutting process.

To ensure continuous and economic cutting of the silicon wafers, special fine wire buttwelding machines join the end and beginning of the cutting wire spools. If the cutting wire breaks in the process, it may be repaired by welding as well. This avoids any new threading-up of the wire into the line and saves a lot of time.

When welding these very fine wires it is vital for the welding process to provide high precision and security of procedure. The high demands for tensile strength of the weld have led to development of special machines for these kinds of wires. The latest generation of these machines works with specially designed controls. For quite some time, welders have been used for high tensile steel wires in the production of so-called ‘steel cord’ for the tyre industry. Being a supplier to the most important steel cord producers in the world, August Strecker benefits from the unique advantage of also being in a position to offer optimum welding machines serving the needs of the solar industry, too. August Strecker GmbH & Co KG – Germany Fax : +49 6431 44221 Email : s.moebus@strecker-limburg.de Website : www.strecker-limburg.de

Whitelegg Machines Ltd – UK Fax : +44 1306 711 865 Email : sales@whitelegg.com Website : www.whitelegg.com

The latest generation of machines works with specially designed controls

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Wire & Cable ASIA – January/February 2008