Shims are thin metals or plastics and are used in various fields and reduce the required tolerances of the joining or mating parts. Shims offer reduced time and manufacturing costs as each part or component need not be precision machined to ensure a perfect fit during the assembly process.
They assist with component fitment reducing accumulated tolerances from the manufacturing phase. They are commonly used to help protect or preserve the mating faces between parts reducing the required time rebuilding or retrofitting.
Various shim materials exist dependent on application. Shim Stock Metals would gladly assist on a recommendation given your requirements.