28 Aug 2001
VICTREX® PEEK polymer replaces ceramic-coated aluminium in wire processing machines
People spend about one third of their lives in bed, and so there is an obvious need to pay special attention to the quality of the design, materials and manufacturing of mattresses. Spühl AG St. Gallen, Switzerland, are global leaders in wire processing equipment for mattress springs and spring interiors, and supply their advanced machines to the mattress and upholstery industry worldwide.
The grippers used in these wire processing machines are subjected to extreme wear and high mechanical forces at elevated temperature. In a new-generation design, Spühl has replaced the traditional ceramic-coated aluminium grippers with parts injection moulded in a lubricated grade of Victrex® PEEK™ polymer. The combination of high mechanical, thermal and tribological properties and cost-efficient, consistent ease of manufacture were key factors in the decision to switch to this high performance polyaryletherketone from Victrex plc.
A spring interior mattress consists of a framework of steel springs surrounded by several layers of upholstery. The springs come in different shapes to meet individual needs including the Bonnell and pocket-type and the special geometry of Cosiflex spring interiors. All mattress springs are manufactured on spring coiling machines. The first step of the process involves coiling the wire into a spring and then cutting to the required length. The gripper forwards the coiled spring to a knotting station where a pre-set end ring diameter is formed. After knotting one end of the wire, the gripper moves across the spring interior to also knot the other end. To minimise loss of height after setting and maximise spring precision, the gripper then guides the tensioned spring between two electrodes for thermal treatment of the steel.
Depending on spring size and diameter, the wire processing machines from Spühl deliver up to 90 spring interiors per minute. During the manufacturing process, the constant friction that is generated from the wire sliding up and down inside the gripper requires a particularly high level of wear resistance. Both the lubricated grade of Victrex® PEEK™ polymer and the replaced ceramic-coated aluminium provide this resistance.
However, the PEEK™ polymer gripper is moulded at Treff AG, Switzerland, in a single process step, whereas the ceramic coating has to be applied to the aluminium part in a secondary operation.
PEEK™ polymer is characterised by a low coefficient of friction and a low wear rate. Furthermore, with a melting temperature of 340°C and a heat distortion temperature of 290°C, this semi-crystalline material also provides the necessary resistance to the high temperature that exists during setting and conditioning the spring, during which the gripper must hold the wire firmly in place.
Reader enquiries
Helen SwarbrickVictrex plc
Victrex Technology Centre
Hillhouse International
Thornton Cleveleys
Lancashire FY5 4QD
United Kingdom
Tel +44 1253 897700
Fax +44 1253 897701
United Kingdom
Notes for editors
Victrex plc, which has its sales, technical and production headquarters at Thornton Cleveleys in Lancashire, UK, had a turnover of more than £58m in the last financial year. The company exports 98 percent of its VICTREX® PEEK™ polymer output to OEMs in the automotive, industrial, medical, food and electronics market sectors in Europe, North America and Asia Pacific.
Information on products, technical support services and sales and distribution contacts worldwide, can be accessed through the company’s web site: www.victrex.com
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The PEEK™ Trademark
For many years Victrex plc has been using the PEEK™ trademark to refer to its brand of Polyaryletherketone. Victrex plc is the sole manufacturer and supplier of the PEEK™ brand polymer worldwide. PEEK™ is a trademark of Victrex plc.
Related images
Spühl AG St. Gallen, Switzerland has replaced ceramic-coated aluminium grippers with parts injection moulded in a lubricated grade of Victrex® PEEK™ polymer due to its high mechanical, thermal and tribological properties and cost-efficient, consistent ease of manufacture.
