A shim is a thin piece of metal or plastic used the separate the sections of molds or carriers as they are made
a wedge or washer inserted into gaps in machinery to help with fitting or alignment
A spacer (usually a wood wedge) placed between a frame and the wall structure to hold the frame in position
A thin piece of material placed between two surfaces to obtain a proper fit, adjustment, or alignment The piece can also be analyzed to measure furnace carbon potential (that is, because while in the furnace it will quickly carburize to a level equal to the furnace carbon potential)