FOCUS ON JOINING |
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Image: Sika. |
when selecting an adhesive. Metal surface preparation, before the bonding process, is essential. Surface pre-treatment improves wetting with adhesive.
“ Oxidations as well as oils and greases, form separating layers on which adhesives can bond well. However, this layer in turn does not adhere sufficiently firmly to the metal, so oxidations / oil / greases must be carefully removed. First clean or degrease the metal, then grind or blast, otherwise impurities can be ground( blasted) into the metal during the grinding process and continue to have a separating effect on the adhesive. Metals that are stored at cold or lower temperatures should be sufficiently tempered before bonding to avoid condensation,” advised 3M.
Mechanical roughening( abrasion) of the surfaces to be bonded is also a simple, highly effective pre-treatment, even for difficult-tobond metal surfaces such as titanium.
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Image: Peel Plate GmbH.
Flat bonding examples.
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Panel bonding in the body shop. |
Image: Peel Plate GmbH.
Edge bonding.
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difficulty in removing the individual sheets. Peeling requires a great deal of dexterity and accuracy. In addition, when peeling laminated sheet, there is a high level of material scrap. The removed films cannot be reused. The use of flat-bonded laminated sheet involves a high risk of injury, as the sharp-edged individual sheets have to be detached with the aid of a knife. The disadvantages can be minimised by using machining production methods when processing laminated sheet parts. In contrast to the punching process, in which the individual sheets are pressed together and are therefore more difficult to remove, the parts are formed by drilling, milling or turning without pressing. This results in better removability,” commented bonding specialist, Peel Plate GmbH.
Edge bonding
In edge bonding or edge binding, individual foils are bonded together only at the edges, as in the case of a paper pad. The minimum thickness of the individual layers for edgebonded shims is 0.05mm for edge-bonded parts. The benefits of edge-bonded sheets include the fact that they are easy to remove, there is minimised material scrap / reduced risk of injury and removed parts can be reused.
“ The disadvantage of edge bonding compared to flat bonding is, on the one hand, the thicker minimum thickness of the individual films and, on the other hand, the less strong bond between the layers, which can be a hindrance in some applications. While laminated sheet parts are manufactured from already bonded laminated sheets, edge bonding takes place only after the individual sheet parts have already been formed. Punching therefore does not have a negative effect on removability here,” concluded Peel Plate GmbH. n
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Flat and edge bonding |
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Bonding involves joining individual layers of sheet metal together. Bonded parts can be used very flexibly, as the individual layers can be removed gradually until the necessary thickness for tolerance adjustment is achieved. Flat bonding and edge bonding are two types of bonding for very thin sheet or foil. |
Image: Shutterstock. com. |
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Flat bonding |
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For the production of laminate or laminated sheet, metal sheets or plastic films are bonded together over the entire surface. The result is foil packages made of extremely thin individual layers with a foil thickness starting at 0.01mm. The benefits of bonded laminated sheet include extremely thin individual foils and the compact nature of the foil packages.
“ One disadvantage of flat bonding is the
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42 | ismr. net | ISMR April 2026 |