Shims are integral for many various parts, serving a range of industries and applications. However, not all shims are created equal, and different shims serve different purposes. Below is a description of four different types of shims, and what they are used for:
Traditional Shims: Shims are thin pieces of material used to fill in small spaces or gaps. Typically a solid piece of metal, this can be a spacer, washer, or filler. Traditional shims are designed into the assembly as pre-planned parts. They are not adjustable, and are designed with specific thicknesses, lengths, widths, etc.
Edge Bond (Adjustable) Shims: These are shims measured for inaccuracies. Technicians using them will pull off one or three layers to compensate for machining errors, whereas other products are designed into the assembly, and then they remove layers. Shims are designed to fit into certain spaces, which are designed for adjustment, but are part of the assembly package. These are for very fine adjustments between parts being assembled. Machined out of foil, 20-80 layers are cut out using CNC machining, edm wire cutting, and other processes. The foil layers are then put into jogs, and the edges are glued with specific aerospace-quality glue. After that, the layers are peeled off to make the length of the assembly to the exact specifications.
Tapered Shims: When surfaces have a taper on them, tapered shims are used to fit in between the other parts. They can make the assembly tight by pushing apart the pieces, and sometimes they will push into the assembly, with the rest of the shim designed into the assembly.
Peelable (Adjustable) Shims: These shims have flat, three-dimensional layers that are glued together so that the technician can peel away layers not needed to get to the exact right thickness. Typically they are 2,000th-3,000th of an inch thick.