 |
Automotive/AssemblyAutomotiveBonding metal sheets in vehicle - bodywork constructionCar bodies largely comprise steel sheets having a thickness of 0.6 to 0.8 mm combined with other new materials, such as plastics and aluminum. There is also a trend in modern car bodies towards a flatter design with as little wind resistance as possible, low weight and hence ultimately reduced fuel consumption. Flat components such as the bonnet and boot, and also door and roof panels, are affixed to ridge-like struts and are hence stiffened. The most common method for joining bodywork components, namely spot welding, cannot be used either on the flat visible sides, because this would result in unsightly points and these would require time-consuming work (filling) to repair, or in the bonding of the many new composite structures. The use of adhesives to solve this problem was introduced about 40 years ago – adhesives are used to join the components together and the number of welding points was reduced to a small number at the edges. Key requirements of adhesives for use in vehicle bodywork construction are as follows:
Crash tests make clear that the alternating fatigue strength and the energy absorption, even after aging, can be considerably improved by using adhesives for some of the joints, compared to wholly spot-welded constructions. The current state-of-the-art involves a combination of bonding and spot welding, so-called spot-weld bonding, and this is used on a large scale for vehicle bodywork construction. The following adhesives are used for bonding sheet metal in vehicle bodywork construction: Plastisol adhesives, essentially filler-containing pastes comprising powder-form PVC, plasticisers and adhesion promoters. For special applications, single component hot curing epoxy resin adhesives are used. Bonding panes of glass into car - bodywork - direct glazingThe panes of glass are fitted after painting and lacquering the car bodywork. In days gone by, the front and rear windscreens were fitted into the bodywork using a profile made of an elastomer that surrounded the glass. A cord-like tacky elastomer sealant was then applied to improve the seal. Since the start of the 1970s, so-called direct glazing has been increasingly used. Moisture curing 1-C polyurethane adhesives, or alternatively MS polymers (modified siloxanes), are used for this. Besides providing an excellent seal, the advantages of this technology are that larger panes of glass can be used and this reduces the overall weight of the car bodywork. This is because the glass panes become a structural material due to the adhesive curing as an elastomer. The rigidity of the structure therefore increases and this so allows thinner metal sheets to be employed. Lightweight design for aircraft, rail vehicle and container manufactureAircraft manufactureFor several decades now, bonding has been one of the most important joining techniques in aircraft manufacture. The specific reasons for this include the fact that bonds have lifetimes of up to 30 years, high resistance to dynamic loads and media and resistance to extreme, and sometimes very rapid, temperature changes, from sub-zero temperatures in the stratosphere to ground-level temperatures in desert climates. The application of bonding technology in aircraft manufacture allows extremely lightweight design due to the consequent use of light metal alloys, fibre-reinforced plastics and so-called sandwich components. Bonding is used for internal structures for manufacturing structures with lightweight honeycomb sheets. It is also used for creating high stress joints, so-called primary structures, for example for the external stiffening of sheet metal of differing geometric size, for sandwich structures made of aluminium or plastic honeycombs with bonded on veneers and for bonding stacks of sheets. The Airbus vertical tail is an example of this. It is composed of an aluminium In the aircraft manufacturing industry, it is mainly epoxy resin adhesives, especially prefabricated films with a curing temperature of at least 120°C, that are used for bonding sheet and sandwich components. Meanwhile in the fuel tanks polysulfide sealants, which are resistant to the aviation fuels, are used as seals to enable the craft to expand and contract as it operates in temperatures from minus 50c to plus 50c. Bernard this need s checking. Rail vehicle manufactureIn rail vehicle manufacture, new components such as those made from glass-fibre reinforced plastic (GFRP) have resulted in enormous weight reduction and have transformed the production process. Construction of containersSandwich panels are widely used for constructing containers and refrigerated containers. Bonding core materials such as plastic foams make these panels, sheets made of mineral materials or honeycomb sheets to cover plates made of aluminium or glass-fibre reinforced plastic. Low and medium viscosity epoxy resin adhesives are used for this purpose and decorative panels also being bonded using such adhesives. Of late, silane modified polymer sealants are also being increasingly used for this. They have good adhesion without prior application of a primer (even on lacquered/painted surfaces) and they have universal application because of their good elastic properties and high UV stability.
AssemblyAssembly (Rigid) ApplicationsThe Assembly (Rigid) Market can be defined rather broadly and includes the following types of applications:
Assembly (Non-rigid) ApplicationsAssembly Non-Rigid includes adhesives used in the manufacture of components and parts which are either fluid or flexible in nature (as compared to rigid assembly of products such as durable goods, machinery, and motors). This market includes numerous applications, including:
|
