Descaling synonymous with cost benefits?
In 2009, over 1,100 million tonnes of crude steel were produced globally. Of this amount, 180 million tonnes were used for the production of wire rod, just one of many other uses. These are huge amounts, which also include an estimated 600,000 tonnes of scale as a by-product. Scale is produced during the rolling process. It clings to the wire and generally offers no advantages for the end product. In fact, it causes damage to the forming tools and reduces the processing speed.
Scale is normally removed from wire by way of chemical cleaning or mechanical brushing, grinding or abrasion. The correct method depends just as much on the product and process parameters as it does on the wire quality and dimensions, not to forget processing speed and the desired surface texture.
A cost-effective process requires foremost that the driving factors of individual costs are known and identified. In this view, the advantages of mechanical wire cleaning over chemical cleaning are quite clear, but are hardly ever exploited fully. In addition to costs purely related to production, these include logistics advantages which can be realized with in-line processing. The technical options for this are already given.
The only limitations of mechanical processes are dimensions and speed. The limitations can be dealt with though – by playing around with different combinations of equipment, such as abrasive belts, drawing dies, lubricants and lubricant bases.
Decoiling, descaling by way of breaking scale, abrasion or brushing, and coating and drawing pose an overall challenge in achieving the technical and economic ideal. That is why WiTechs GmbH, located in Schwerte, Germany, works together with other specialists, whose abilities in production engineering contribute to the success of a project.
Cost benefits of up to 75%
The entire range of production equipment before the drawing machine – i.e. overhead wire pay-off, scale breakers, grinding, hot rinsing and coating units – is available from WiTechs. Drawing machines and winders are produced by Ernst Koch GmbH&Co.KG in Ihmert, Germany. Abrasive belts from VSM AG in Hanover allow a service life of up to 6 tonnes of wire rod. Borax free lubricants and bases are available from Traxit GmbH in Schwelm. The pressure drawing die system from Paramount Die Europe is used for drawing.
Throughput speeds of up to 5m/s are currently being achieved in wire brushing. Thanks to a modular design, wire dimensions know practically no boundaries – the largest diameter is currently 30mm.
Wire abrasion offers many advantages for determining surface finish and surface topography. The maximum throughput speed is normally 3.5m/s. Continuously cleaned surfaces make spooling speeds of up to 50m/s possible in in-line processing.
The process is finished off with wire rinsing and coating with a lubricant base. This helps create a surface ideal for drawing. The continuous measuring of the lubricant makes the process safe. As a result, costs can realistically be reduced by 75% in wire rod descaling.
The associated technology is constantly being further developed at WiTechs. The company will present its latest innovations at Booth H 39 in Hall 10 at the wire trade show in Duesseldorf.
Auf der Hofestatt 7, 58239 Schwerte, Germany
Tel.: +49 2304 96810-0
Fax: +49 2304 61298
e-mail: sales@witechs.de