Sponsored content

Sometimes the smallest parts of a complex system can play an outsized role in its proper functioning. Such is the case with shims, which are thin pieces of material primarily used to fill unwanted gaps. Shims ensure the efficient and effective operation of machinery by fixing angular misalignments between rotating components in equipment such as pumps, compressors, generators, engines, turbines and gearboxes. Shims compensate for parts with poor tolerances, ensure level mounting, create level surfaces and can even be used as wear parts between mating surfaces.

Shims are put to work in myriad applications across a wide range of industries. They can be used to set the preload on a bearing; position a hole shaft to provide an exact alignment so that two gears intersect; position a cover to create a specific gap for fluid to flow inside a pump; and fill a gap under mounting feet to ensure a machine is level. Their applications span a variety of industries, including aerospace, material handling, mining, oil and gas, medical and chemical.

Figure 1: Color coding shims allows quick and accurate identification of the correct thickness. Source: Artus CorporationFigure 1: Color coding shims allows quick and accurate identification of the correct thickness. Source: Artus CorporationArtus Corporation has been precision manufacturing shims since 1948. Artus’ custom shims and shim stock are available in an assortment of sizes made from high-quality materials with superior heat resistance. Competing products might have a similar outward appearance, but are potentially comprised of cheaper materials with inferior properties.

Color Coding

Plastic and aluminum color-coded shims and shim stock from Artus provide a number of advantages over other material types. Color coding allows workers to quickly identify the appropriate shim thickness with just a glance and without needing to measure its dimensions with a gage. Additional time can be saved by arranging shims on a pegboard for convenient access.

Artus’ plastic shims are lightweight and easy to use. Although they hold their shape during bending to prevent crumpling, they are pliable enough to create an effective seal. Furthermore, they are impervious to oil and will not absorb moisture, making them a great choice as a seal to keep lubricants from leaking out of cavities. Serving the dual purposes of shimming and sealing, they can eliminate the need for O-rings or gaskets in certain applications.

Temperature Resistance

Plastic shims resist temperatures up to 200 degrees Fahrenheit. This is sufficient for most applications because regular lubricants have working temperatures below 200 degrees Fahrenheit. If temperatures rise too far above the recommended operating limit, the material can start to plastically deform, compressing to a thinner thickness and causing a loss of preload force or the loosening of a joint.

In this case, aluminum shims are a better choice. Aluminum withstands higher temperatures than plastic and is effective up to 800 or 900 degrees Fahrenheit. Available in thicknesses measured in thousandths of an inch, aluminum shims might be expected to behave like foil, crumpling at the slightest touch. Instead, they are structurally strong, rigid and hardened to resist wrinkling and bending. They also will not deform when exposed to compressive forces and are free from burrs around their edges. In addition, aluminum resists corrosion in applications where the product is exposed to sea water.

Figure 2: Artus offers shims in a variety of thicknesses, each coded in a specific color. Source: Artus CorporationFigure 2: Artus offers shims in a variety of thicknesses, each coded in a specific color. Source: Artus CorporationThicknesses

Artus has been supplying plastic and aluminum shims for over 65 years for a variety of applications, including adjustment of tapered roller bearings. Artus offers plastic shims in thicknesses from 0.0005 in. to 0.060 in. Eleven thicknesses from 0.0005 in. through 0.0125 in. are made from an oriented polyester with a temperature resistance up to 200 degrees Fahrenheit. Three thicknesses (0.015 in., 0.020 in. and 0.030 in.) are available in two formulations: a polyester with a temperature rating of 140 degrees Fahrenheit and a polycarbonate that withstands temperatures up to 200 degrees Fahrenheit. Another four thicknesses (0.025 in., 0.040 in., 0.050 in. and 0.060 in.) are available in the 140 degree Fahrenheit polyester formulation. Aluminum shims are available in thicknesses from 0.001 in. through 0.030 in. Each thickness is coated in a different color, making it easy to quickly select the right shim.

Cost

Shims can provide a number of economic benefits. Manufacturing parts with very tight tolerances often requires costly machines capable of operating with high precision. By relaxing tolerance requirements and allowing shims to compensate for the lack of precision, capital expenditures can be minimized. Shims can also save money when placed between mating surfaces subjected to friction wear, preserving expensive machined parts. Finally, shims can reduce maintenance costs by eliminating misalignments that can cause premature equipment breakdown.

Materials

When considering which shim materials to use for a project, it can be helpful to keep in mind the relative costs of each material. Plastic shims are generally cheaper than those made of metallic materials like aluminum, brass, stainless steel and cobalt, although the price for plastic shims increases for greater thicknesses. Stainless steel is, in general, expensive but very effective, and should be deployed on an application-specific basis.

To keep shim budgets under control, thin plastic shims can be combined with thicker aluminum shims. Thin plastic shims at the ends of a shim stack provide a seal that can, for example, prevent lubricant from leaking from a bearing, while thicker aluminum shims in the center of the stack economically fill the rest of the gap. This cost-effective approach sandwiches the two material types together to provide the benefits of both while keeping expenses down.

Summary

Shims are vital components in many modern designs. They ensure precise alignment and positioning to match design specifications, fill unwanted gaps to maintain structural rigidity and compensate for imperfect tolerances in other parts. Plastic and aluminum color-coded shims and shim stock from Artus Corporation are an excellent choice for current and future projects. With convenient color coding and high-quality materials, these shims precisely fill the gap.