Floating boss eases assembly

Problem: When bolting a large component to an assembly, it is very unlikely that all the bolt holes are going to be in exactly the right alignment. This is known as 'tolerance accumulation' and occurs in most assembly operations of this nature. In engine assembly, fixing an accessory bracket onto the engine is particularly troublesome. The usual solution is to force the bracket to fit, which places a lot of stress on the assembly and can lead to premature failure, or to make careful use of shims, to get everything aligned and fitting together. Shims are usually deemed unacceptable in assembly operations as they are time consuming in most production environments. Solution: Specialist automotive engine supplier, Integral Powertrain, has developed a simple, cost effective fastener solution called a 'floating boss' that uses sliding conical inserts that automatically position themselves during engine assembly. As the bolt is tightened to the prescribed setting, the inserts lock themselves into place. A design engineer at Integral Powertrain told Eureka: "The clamp load also results in radial pressure inducing compressive yield locally in the surface of the bracket and provides strong axial location." He went on to say that finite element analysis (FEA) software was used by the company to optimise the proportions and taper angle of the floating boss, in order to give a consistent solution for the range of friction conditions likely in a production environment. Applications: Aside from its obvious use in the vehicle engine assembly, the floating boss could also find applications in other production environments where time is critical. Any assembly operation where a large component needs fixing to an overall assembly. DP