MOTORS, DRIVES & TRANSMISSIONS Joining the technology of BY ROBERT IGNATZEK, GLOBAL TECHNOLOGY MANAGER, HENKEL AG & CO. KGAA Development of new materials with their wide-ranging application potential poses major challenges for modern bonding technology. In production, adhesive technology enables optimum use of specific material properties and implementation of new construction methods such as lightweight construction. Use of structural adhesives has also become essential to the widely used mixed construction method as well as the application of all kinds of metal, synthetic and fibre composite materials. In recent years, the use of modern adhesive technologies has become increasingly prominent in the industry. There is a good reason for this, as high-performance adhesives deliver numerous advantages for constructors and processors alike. In particular, the property of bonding all kinds of materials quickly and securely is one of the reasons why adhesives are now regarded as an established part of many production processes. Almost all types of metals – both conventional standard steels and stainless steel and aluminium – as well as synthetic and fibre composite materials and glass or ceramics can be combined adhesively with professional application. In this way, the specific material properties can be optimally utilised for a component in product manufacture. Structural adhesives compared with other fitting methods In addition to their all-round versatility, there are other factors in the increasingly important role of adhesives in trade and industry. On a like-for-like basis, the traditional connection technologies have familiar disadvantages. Mechanical processes such as riveting or bolting only enable transfer of force at specific points. The flux results in peak stresses at the whole or spot edges that increase the risk of fatigue fracture and thus adversely affect the dynamic and static strength of the bond. In contrast, when bonding connections are effected correctly, the stress or load transfer is more evenly distributed across the entire bonding surface. Compared with traditional fitting methods, bonds are superior in the presence of dynamic stress. In addition, the parts to be bonded are not weakened by the drilling of holes. Compared with welding and soldering, the use of adhesives chiefly stands out by virtue of its flexibility. Heat-sensitive materials such as aluminium or plastic as well as very thin components can therefore be securely bonded. There is no negative impact on the strength of the material here. The low heat build-up is another key criterion when processing fitting parts that already have their final surface finish, for example chrome-plated steel. As a non-conducting material, cured adhesives also have an insulating effect, thus preventing contact corrosion. Technology verview Depending on the field of application, various adhesive technologies with specific product properties are available for structural bonding. This chiefly involves 1- or 2-component reaction adhesives that cure at room temperature or as a result of heat. Henkel covers the entire spectrum of adhesive technologies. This includes epoxy, acrylics and polyurethane. One distinguishing criterion is the difference between rigid and flexible bonds, both of which have different advantages. Conventional rigid bonds are mainly used for high mechanical transfers of force and replace traditional fitting methods in this case. They enable a tough adhesive bond on the surfaces to be joined, and meet all practical requirements in terms of their strength properties, as demonstrated by numerous examples in the aircraft and vehicle industry. In contrast, elastic adhesives are increasingly being used in the presence of high dynamic stress resulting from temperature differences or component movements. Practical Application in Industry, who benefits? Adhesive technology can be practically integrated into existing production processes in all industrial sectors. Depending on the application, the coating THE FUTURE 24 June 2016
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