The Transportation & Marine Market is very wide and includes numerous applications in such areas as:

 

Six areas discussed in more detail below are:

 

 

Automobile bodies mostly comprise steel sheets having a thickness of 0.6 to 0.8 mm. The trend in modern car bodies is towards a flatter design with as modest wind resistance as possible, low weight and hence ultimately reduced fuel consumption. Flat components such as the cover and trunk, and also door and roof panels, are affixed to ridge-like struts and are hence stiffened. The most general method for joining bodywork components, namely spot welding, cannot be used on the flat visible sides because this would effect in unsightly points and these would require time-consuming work (filling) to repair. The use of adhesives to resolve this difficulty 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. The bonding process had to be introduced into the relevant production line sequence. The construction of car bodies puts enormously high demands on structural bonding expertise: Special surface pretreatment of the metal sheets, which is essential for creating high-strength joins having high stability, is not likely on a mass production line. In addition, the substrates are also still covered with corrosion protection oils during the production process. These can only be removed before the final process step.

 

Key requirements of adhesives for use in automobile bodywork construction are as follows:

 

·         Ability to form structural bonds with defined characteristics over the lifetime of the

          component under operating loads;

 

·         Stability at 170 to 230°C for ca. 30 minutes during the painting process;

 

·         Resistance to running and washing away in the non-cured state;

 

·         Ability to be processed automatically;

 

·         Capability to penetrate for spot-welds as crack stoppers.

 

Merely hot curing adhesives meet the above mentioned necessities. The adhesives particularly developed for these applications are designed in such a way that in the non-cured state up to 20 weight percent of oil can be taken up via dissolution. Though, in practice when using the adhesive, so much oil is forced away by the adhesive that immediate initial bonding of the adhesive is typically guaranteed. The remaining oil is taken up by the adhesive and forms part of the adhesive film.

 

The high temperatures speed up the dissolution of the oil by the adhesive. The oil is basically uniformly distributed in the cured adhesive film and does not diffuse back to the surface.

 

Crash tests make clear that the alternating fatigue strength and the energy absorption, even after aging, can be significantly 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 joining 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.

 

Example applications are: stiffening and flange seams on hoods and trunks, doors and roof structures.

 

 

“Glued cars” are safer and extra economical. It is no wonder then that adhesives have entered what used to be the domain of welding in the automotive business. For example, in 2001, 33 linear feet (about 10 meters) of adhesive were used for the body of the BMW model, today 500 linear are used. About 9% of annual adhesive production is used in vehicle construction.

 

Nowadays a car contains up to 40 lb (18 kg) of adhesives. And for good reason: crash tests have demonstrated that glued cars do surpass than welded designs. What is more, adhesives do not have an effect on how parts are assembled. Other techniques counting welding, riveting or bolting impact the rigidity of assembly materials. In the event of an accident, adhesives act like a buffer. That said, automotive engineers design car bodies so that as much impact energy as possible is changed into deformation energy, rendering it harmless. This gives maximum safeguard to passengers. In the present day, so called crash-resistant adhesives are used for this purpose. Though enhanced safety is not the only advantage of adhesives in vehicle manufacturing. If doors were welded, the outside would have to be laboriously reworked to ensure a good look.

 

For glued doors though, there is no need for reworking, ensuing in lower production costs. In order to ensure that the windshield, which is subject to massive loads (imagine the headwind when riding down the highway at 80 mph) and remains impeccably in place in the frame, the automotive industry uses advanced high performance adhesives. These promise perfect hold overall, even under extreme conditions including wind, rain or hailstorm,blistering heat in the summer or bitter frost in the winter. Directly glued front and rear screens ensure lower air resistance, thereby reducing gas consumption.

 

For modern cars, manufacturers use a range of resources besides steel sheets. This blend of materials is also held together by adhesive. Incidentally, the use of adhesives is not restricted to car manufacturing but is used in other vehicles as well. Even as an average rail car built between 1981 and 1993 contained some 22 lb (10 kg) of adhesive, some modern rail cars used nowadays weigh in with up to 1100 lb (500 kg) of adhesive.

 

The panes of glass are fitted after painting and lacquering the car bodywork. In days gone by, the front and rear windscreens were fixed 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 more and more used. Moisture curing 1-component (1-C) polyurethane adhesives, or alternatively modified siloxanes (MS) polymers are used for this. In addition providing an brilliant 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 turn into a structural material owing to the adhesive curing as an elastomer. The rigidity of the structure therefore increases and this so allows thinner metal sheets to be employed.

 

 

 

The development of flight over the last six decades is pretty impressive. Today we jet all over the globe as if it were the most natural thing in the world. Though, no less remarkable is the development of adhesives during the same period. Over the years, this convenient household helper has become a high-tech tool.

 

For quite a few decades now, bonding has been one of the most imperative joining methods in aircraft manufacture. The precise reasons for this comprise the fact that bonds have lifetimes of up to 30 years, high resistance to lively 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.

 

High-tech adhesives are now obligatory in aviation. They offer comfort, stability and, above all, safety above the clouds. In many areas of the industry, they have taken the place of rivets, bolts and welding and are still gaining ground. Bonded assemblies can be discovered in practically all areas of an airplane: helping to increase stability, safety and passenger wellbeing. Today, a modified, or optimized, epoxy technology is increasingly used in the production of so called composites, restricting the use of unadulterated metal adhesive to strictly defined areas. 

 

 One benefit of the adhesive elements in paste form is obvious. For the reason that of its consistency, it can also be used locally and its compensatory tolerances permit for a steady bond. In addition, it offers high steadiness because the use of adhesives allows the structure to remain intact during the binding process. This offers the chance for new composite materials to be developed.

 

Weight lessening is an economically advantageous aspect, in addition to the technical advantages presented by adhesives. Every pound that is saved reduces the working costs of an airplane; and savings in the production costs and -- based on the overall life of the vehicle extremely important for the auto and aviation industry. The application of bonding technology in aircraft manufacture allows particularly 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 furthermore used for creating high stress joints, so-called primary structures, for example for the outside stiffening of sheet metal of differing geometric size, for sandwich structures made of aluminium or plastic honeycombs with glued on veneers and for bonding stacks of sheets. The Airbus upright tail is an example of this. It is composed of an aluminium lattice framework and veneers made of carbon-fibre reinforced epoxy resin adhesive. The individual components of the veneers are pre-cured and the entire component is glued in an autoclave.

 

 

In the aircraft manufacturing industry, it is mainly epoxy resin adhesives, specially prefabricated films with a curing temperature of at least 120°C, that are used for bonding sheet and sandwich components. The lap shear strengths that can be attained are about 20 MPa (static) and 1 MPa (dynamic). The result of peel forces is avoided by variety of design. Though, a peel resistance of about 4 N/mm is sought for assurance.

 

Keeping in mind that today there are already approximately 250,000 adhesive formulas globally which are completely specialized in application, it becomes clear that there is hardly any other technique of combining components as specialized as the adhesive industry. This is not only, but mainly, true in the aviation industry.

 

 

 

 In rail vehicle manufacture, new components such as those made from glass-fiber reinforced plastic (GFRP) have resulted in enormous weight decrease and have transformed the production process. In Europe, ADtranz regional trains are produced using a frame structure consisting of tensile and compression struts in a triangular arrangement. This is the lightest design for bearing structures. Owing to the frame structure, it is not essential to weld on metal sheets to take up the shear stresses. There are only tensile and compressive forces in the struts. In order to enclose the frame, large outer skin elements are glued to the supporting metal structure using moisture curing one-component (1-C) polyurethane adhesives. No complex straightening and filling work is necessary, as is the case when welding is used to connect the metallic outer skin elements. The GFRP elements that are used for the outer skin have a sandwich structure and therefore provide superior thermal insulation and have very good acoustic properties. As no heat distortion occurs, dissimilar to when welding, the outer skin gives the rail vehicle a ready painted, level, smooth and flush outer surface with no extra work having to be undertaken.

 

Bonding a metallic framework structure with components built of fibre reinforced composite plastic can only be economically and dependably achieved using bonding technology. In order to compensate the different linear deformations of the structure and outer skin when they are exposed to heat, a extremely elastic, solid film of adhesive is used. The resulting bonds have high strengths, even when subjected to repetitive temperature fluctuations in the range between -40°C and +80°C and under impact-like stress. They also have very good confrontation to aging, even in moist environments. The thickness of the bonded joint varies between 4 and 18 mm. This depends on the size of the machinery, which can be up to 8.5 meters long and so subject the bonded joint to very high shearing deformation. An added advantage of this type of structure is the high damping and the positive effect this has on the dynamic operating characteristics and ride comfort.

 

All in all, these provincial trains are about 25% lighter than comparable conventional trains, and they also have improved ride distinctiveness, lower production costs and reduced energy requirements for operation.

 

 

 

Sandwich panels are widely used for constructing containers in addition to refrigerated containers. These panels are built by bonding core materials such as plastic foams, sheets made of mineral materials or honeycomb sheets to wrap plates made of aluminium or glass-fiber reinforced plastic. Low and medium viscosity epoxy resin adhesives are used for this function and ornamental panels also being bonded using such adhesives. Of late, MS polymers are also being more and more used for this. They have fine bonding without prior application of a primer and they have universal application because of their good elastic properties and high UV stability.