The use of adhesives in component manufacturing ranges from automotive headlamps to plastic body components (e. g., hoods, tailgates) to interior fittings to cabriolet soft tops, including a wide range of adhesives employed. Table 3 lists applications without any claim to being complete. Looking at the plastic components it is obvious that there are many different types of polymers, but the adhesives selected are basically polyurethane and epoxy-based compounds. The latter are rarely used. The main difference among them is in the way they are formulated: one or two components, cold setting or curing at higher temperature, liquid or paste, and so on. Because of the easy processing, the newly developed two-part acrylic adhesives, which are applied in a no-mix formulation, are very interesting. The A component is applied to one side and the B component to the other side of the surfaces to be bonded. After being fixed together, the adhesive cross-links in a few minutes. Bondings manufactured using this type of adhesive show good shear and peel strength results and high durability at impact loads. Applications include the bonding of protection plates to the sill beam or the joining of exterior lighting housings.
In cabriolet-cover manufacturing, solvent adhesives, synthetic rubber — or polyurethane-based, are used for sealing the folding top seams and for bonding the soft
Figure 12 Robotized assembly of a windshield. |
cover to the hood linkage. Adhesives are often mixed with hardener to improve the heat resistance of the bonding. Hot-melt adhesive foils are also employed. Preformed butyls or butyl sealant pastes or moisture-curing polyurethane adhesives are used for additional sealing.
Many interior fittings (e. g., instrument panel, door and sidewall panels, package trays, seat linings, boot carpetings, rear window shelves, etc.) are often manufactured by vacuum drawing and laminating the cover sheet material (leatherette, textile, leather, etc.) onto the trim panel. The use of hot-melt (also cross-linking) adhesives and water — based polyurethane adhesives (with hardener) is state of the art for this type of component production.