Magnetic Pulse Swaging

High rate deformation of metals can under the right conditions cause metals to plastically deform beyond the their normal breaking points and this is referred to as super-plasticity otherwise known as a rate effect. Magnetic and explosive propulsion methods have been shown to be highly suited to inducing high rate deformations in common ductile materials like steel and aluminium. A feature of high rate deformation (magnetic forming) is that virtually no spring-back occurs after the forming force is removed. These characteristics are useful for forming friction joints in which the frictional resistance is the result of enhanced asperity welding, thus it is another form of impact welding but it requires that joints are made coaxial so an outer body presses against an inner body to maintain contact pressure, the friction resistance is directly proportional to contact pressure, but because there is virtually no spring-back after high rate forming the contact pressures are very high as are the joint strengths.  

It is already common to make mechanical interlocking joints by magnetic swaging, an example being the highly reliable torque rods used in control systems on modern aircraft. However despite much effort these structures have not gained favour in automotive transmission shafts because they tend to develop backlash if abused. By eliminating the mechanical interlocks and making the joints between smooth parallel faces and introducing a friction enhancing chemical treatment, genuine high friction joints are formed that eliminate the risk of back-lash because the joints strength easily exceeds the strength of the weaker material. The introduction of friction enhancing Trib-Gel treatments into magnetically swaged joints creates distributed asperity welds across a larger area of joint, thereby avoiding the stress raiser effect of narrow band welds, this improves the fatigue characteristics of the joint which significantly raises the strength and the durability of transmission shafts while reducing the manufacturing difficulties associated with guaranteeing full welds in magnetic pulse welding designs. The process is well suited to joining aluminium tube to steel terminals.

for more information email: info8@tribtech.com

The TribTech name derives from "tribos" - Greek for 'rubbing'. 'TribTech' is a trade name used by Ball Burnishing Machine Tools Ltd. of 12 Brookmans Av. Hatfield, Herts. AL9 7QJ. United Kingdom;  Company Reg. No. 1408807, VAT Reg. No. 421 6210 04; a knowledge based company that develops, patents and licenses technology. All rights reserved by Ball Burnishing Machine Tools Ltd. Last modified: May 01, 2008 copyright © 1999/2008. The information and data provided herein should be considered generally representative for the tools and technologies described. In all cases users should carefully evaluate the tools and technologies to determine their suitability for a particular purpose.