Hands-on advice at Joining event

Hands-on advice at Joining event Henkel Loctite ran a very practical, hands-on workshop at the recent 'Joining Technologies' Design Day – held in Cambridge on 21 May 2008. Using a range of different adhesives, Henkel Loctite product specialist Bob Goss took delegates through a series of adhesive bonding applications – including cylindrical part bonding, practical advice on improving threadlocks, and tips on how best to join plastics and rubber components. At the same time, he posed a design problem – which is illustrated above. He asked delegates to nominate what they thought was the best way to stick two overlapping pieces of flat steel together. There were two options, each with a bond area of 1000mm2 – one was a ‘long’ join, the other a ‘wide’ join? “As you increase overlap length you do not necessarily increase strength,” he said. “The wider the joint, the better the peel strength. If you are designing a joint, it’s better to increase width rather than overlap length.” For future reference, he told delegates to visualise two pieces of sticky tape overlapping in the same way – which seemed to make things easier. The fact that adhesive bonds have different failure modes is not only helpful in design studio. It also helps at home if you stick your fingers together – and Goss’s advice is not to simply try and wrench your fingers apart. “If you do that, you’re in danger of ‘substrate failure’,” he said. “Instead, you should ‘peel’ your fingers apart.” * Threadlocking, one of the themes dealt with in the workshop, is covered in more detail by a new Loctite website (www.loctitesolutions.com/uk) and brochure. The site contains product details and a host of useful information – including a calculator that shows how much adhesive is needed for specific situations. There are also case studies, and an overview of threadlocking. Colin Chapman, marketing manager at Henkel Loctite, said: “Threadlocking adhesives need to be secure – yet, in many cases, there is also a requirement for easy disassembly when it comes to servicing arrangements. Using the right adhesive is, therefore, vital. The website and guide help engineers through the choices.”