PRODUCTS
Control processes ensure the highest spring quality
In order to meet customers’ expanding requirements, Lesjöfors has made major investments in measuring equipment at its plant in Swedish Herrljunga.
L
esjöfors manufactures all types of springs with a wire diameter between 0.03mm and 65mm. Each production unit is specialised in its own market and product line, but a common requirement for all is the high quality
standard each Lesjöfors spring must live up to. With theoretical models spring properties can be calculated with good accuracy. “For all traditional types of springs we use our own
developed software and for more complicated geometries we use specially adapted FEM programs. Rapid pulsed load and transient phenomena are areas that, in some applications, are of importance,” says Anders Berntzen, quality technician at Lesjöfors Industrial Springs.
Investments in measuring equipment To become even better at measuring that the manufactured
products are top class, Lesjöfors has made a major investment in new equipment. All production in Herrljunga is now carried out in fully automated processes. Measuring equipment is placed in the production line so operators are able to perform their spring tests in direct connection to their workplaces. Previously they had to go with the springs to a special test chamber.
Accurate measurements with documentation Italian Micro Studio who specialises in the measurement needs for spring manufacturers has supplied the new measuring equipment.
“We follow an overall control plan and it says check the first and the last piece with continuous inspections during the process. For example, if we have 250,000 springs in a series, which is not unusual, the measurement takes place continuously approximately every 30 minutes. If we have a small series of 3 to 5 springs we measure all of them in most cases,” says Anders Berntzen.
All-round spring competence Lesjöfors explains that to get the requested spring properties
a company need a good knowledge of manufacturing materials, after-treatments such as heat treatment, grinding and shot peening and other performance-enhancing measures. Henry Berner, strategic sales manager for all Lesjöfors´ units
in Sweden, adds: “Lesjöfors´ strength is when a customer comes to us with an immediate problem such as ´we want a spring with this or that characteristic’. We can then participate from the project start and, based on our extensive experience, develop optimal solutions for the customer.”
System solution with RIVTEX
The RIVTEX system solution from Arnold Umformtechnik and Arnold & Shinjo GmbH is a high-quality alternative to conventional welding that cuts parts assembly costs whilst assuring every quality requirement.
W
ith the RIVTEX system studs and nuts are pressed into the ready-to-assemble sheet metal parts such that they do not fall out and are characterised by high twisting moments and press-out forces. The
fastening process, controlled by intelligent tool technology, remains integrated in the press process and replaces at least one complete operation. Tangible cost reductions in industrial assembly processes can only
be made throughout the process chain. Arnold & Shinjo GmbH & Co KG was set up for this purpose. It offers consultancy and support to customers and supplies the corresponding tool technology. The company offers a package stud/nut solution including a process technology specially tailored to the product benefits. The RIVTEX range comprises of clinch studs and self-piercing
nuts and addresses the requirements arising from steel and aluminium sheets less than 1mm thick. Arnold Umformtechnik explains that RIVTEX fasteners cannot
fall out because they are pressed firmly into the sheet metal component. With their large bonding area, RIVTEX fasteners are extremely stable against press-out forces and torque, and so
152 Fastener + Fixing Magazine • Issue 76 July 2012
develop their own safeguard against failure. RIVTEX fasteners replace welding and the associated environmental hazards. The surface structure around the fastening is protected and there is no welding spatter - so no requirement for additional reworking after application. The risk of corrosion (due to the 90% level of zinc coating in sheet steel welding) can be eliminated with the RIVTEX alternative. Unlike welding screws and welded nuts, these fasteners can
be applied at the same time as the sheet steel is stamped and pressed. Arnold & Shinjo supply standardised tool and feed technology which enable several fasteners to be emplaced in a single stroke. RIVTEX fasteners can be processed on the fast- running tool in exactly the same way as in the transfer press or pressing line.
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