To suit their purpose, Slotted Steel Shims need to be produced as flat as possible. The Steel Supply Company can manufacture perfectly flat shims with literally zero practical deflection by cutting the shims from plate stock on a laser table. The problem with this method is higher costs, which escalate even further as the shim thickness increases.
Steel Manufacturing Blog: Keeping it Steel
The Steel Supply Company uses a variety of processes when manufacturing Slotted Steel Shims. For stock sizes Punch and Die Stamping is the most effective. For made to order sizes or multiple slot shims laser cutting produces very accurate results. Heavier material like 1/2” thick or thicker tends to be more economical using a High Definition Plasma table. Regardless of the process our customer, the steel fabricator and erector, requires the same thing, i.e. accurate, flat shims that can be installed with no hesitation or interruption and that provide 100% surface contact.
For the construction trade, plastic shims are an essential tool but care must be taken to assure they are rugged enough for the intended use. Before even considering the compressive strength of a plastic shim you must first ensure that is it should be solid with uniform plastic throughout. Lower cost hollow plastic shims are manufactured but do not deliver the strength or durability required for most construction projects.