Sheet bonding is a process in which individual sheet layers are connected to form a peelable precision shim. Bonded parts can be used very flexibly. The layers can be removed one by one until the necessary thickness for tolerance balancing has been reached. The bonding of sheets can be done in two ways: whole-surface or edge.
To manufacturer layered material or laminated shim stock, the sheets or plastic foil are bonded together across their entire surfaces. This process allow foil packages consisting of extremely thin individual layers (as little as 0.025 mm) to be manufactured.
whole-surface-bonded laminated shim stock parts
The advantages of this type of bonding are the extremely thin individual sheets and the compact characteristics of the foil packages, which are achieved by the very strong, whole-surface bond between the individual foil layers.
A disadvantage of whole-surface bonding is the difficulty of peeling away individual layers. The peeling procedure is very time-consuming, since it must be carried out with a great deal of dexterity and precision. In addition, peeling laminated shim stock involves large amounts of waste material. In many cases, too many layers are peeled off. Nor can the peeled layers be used in any way. The use of laminated shim stock that has been bonded across the entire surface of the individual layers also involves a relatively high risk of injury, since the layers have sharp edges and must be separated with a knife.
These disadvantages can be minimized by means of laminated shim stock part manufacturing methods involving machining. In contrast with stamping, in which the individual layers are pressed together, making them more difficult to separate later, the parts are formed by means of drilling, milling, or turning without pressing them together. This results in better separability.
Edge bonding is a version of sheet bonding in which the individual layers are bonded only at the edges, much like a notepad. The minimum thickness of the individual layers in edge-bonded parts is 0.05 mm.
Edge-bonded slotted shims
The advantage of edge-bonded shims is their much greater separability than that of laminated shim stock, which saves time and minimizes wastage and danger of injury. Separated layers can be used in other applications. Easy handling means that their is not much risk of mistakenly separating too many layers at once.
The disadvantages of edge bonding compared to whole-surface bonding is the greater minimum thickness of individual layers and the weaker bond between layers, which can cause difficulties in some applications.
While laminated shim stock parts are manufactured using layer material sheets that have already been bonded, edge-bonded parts are bonded only after the individual sheet pieces have already been shaped. This means that stamping does not impair peelability.