Examining Functionality Differences between Shims and Washers


Differences Between Shims and Washers

Any mechanical machine requires precise moving parts in order to produce exceptional results. This relates to medical equipment, aerospace technology, and automotive innovations. Because of the important role of these machines, every part must fit well and perform consistently for long periods of time. Washers and shims are regularly used in a variety of industries to ensure proper fit and flexibility, and improve performance for each application.

Basic Functions


Shims and washers play unique roles in contributing to optimal efficiency and better overall results; however, they both have different functions. For example, shims level a space for working, fill gaps or excess space, and provide increased support, while washers are used to maintain consistent temperatures and change drag precision with pressure.

Shims differ from washers in function, materials used, and applications. Typically, a shim is fabricated in the shape of a wedge, and tapered to fill spaces or gaps between two surfaces. They are used to create a level surface, stronger support, or adjust the fit between two surfaces.

Shim stock is the type of base materials used specifically for shim manufacturing. The correct choice of stock is determined by the intended application and function of the shim. Typical materials include, but are not limited to plastic, rubber, wood, stone, metals, and layered paper or aluminum foils, called laminated shims. One of the advantages of using laminated shim stock is that laminated shims are fabricated in layers that can be peeled off one at a time until the precise thickness required is achieved.

Calibration foil shims are used to create a coating thickness standard on a form, surface finish, or material substrate. Precision foils are an accurate method of adjusting calibration for thickness when the thickness must be very precise and accurate. Calibration foil shims are single foil or laminated in layers. They are used in many industries, such as on construction sites and in laboratories.

Certified plastic shims are an alternative to metal shims. They are typically not as accurate as a metal shim, but are a cost-effective solution when your project doesn’t require the calibration specifications that necessitate metal shims. Applications include protecting probes from damage or wear when used with abrasives or on hot surfaces. Also, these shims are used with Type 2 electronic gauges for coating thickness standards.


Washers are used to reduce friction, allow thermal expansion, reduce creep issues, and allow for fine-tuning.

Typically made from many materials¹, like metallic, plastic or rubber, washers are used in sizes that range from miniscule—a washer that could fit on the point of a ball-point pen—to huge for fitting super-sized machine parts, and every size between. Many industries use washers for fitting functions on equipment. For example, in the medical field, a washer might be used for micro-surgical tools whereas in the oil industry, a washer may be used for a rigging machine.

Common washers, whatever the size, are usually disc-shaped with a hole, normally located in the center of the disc, and are used for load distribution when connecting parts with threaded screw and nut fasteners. Washers typically have an outer diameter measuring two to three times the inner diameter. Uncommon washers are found in various custom designs to accommodate more specific fit solutions on custom equipment.

Functions for machines and equipment improve when washers are used as spacers, wave washers or spring fittings, locking devices, vibration reducers, pre-load indicators, and wear pads. Washers improve the fit and function of nearly every multi-component device.

Washers are categorized and inventoried for easy identification.

Plain washers evenly distribute weight or loads, and protect surfaces where they are joined, or insulate materials² from reacting to each other as in corrosion or in electrical applications.

Spring washers prevent connectors from loosening under several conditions, like weight changes, pressure, movement, or friction and vibrations. Spring washers are made with specific axial flexibility functions.

Locking washers also include the spring washer class, and prevent unwanted loosening or slipping connections through unscrewing during use, movement, or transportation. Like the name suggests, locking washers “lock” hard and are designed for strong resistance to rotating. These washers are often split, which creates an edge-to-block rotation, and can also be machined to have gripping “teeth.”

The American Standards Institute³ divides general use washers into two types and many forms. Type “A” washers are made of steel, used specifically for non-precisional functions. Type “B” washers are graded for tightness properties and toleration, specified for bolt sizes as narrow, wide, and regular.

Our Precise Services

We have been working with clients from many industries since 1907. From construction sites to medical fields and aerospace industries, our focus is providing unique solutions for your manufacturing excellence. Your specific selection of quality, size, diameter, thickness, tolerance, shape, and quantity is precisely crafted from any of 300 raw materials. We produce the highest-quality products in today’s market, servicing all sizes of original equipment manufacturers.

Phoenix Specialty Manufacturing is an American-made manufacturer, and is proud to supply every industry that utilizes every type of common or custom shim or washer imaginable with top-quality parts. With an extensive inventory to serve your company quickly and efficiently, our stock products are shipped within just a few days. Custom orders and designs are also handled with the quickest turn around in the industry, typically within a two-week period. We also offer many special services, such as plating and medium- to short-run custom parts.

We specialize in the uncommon specializations required, such as waterproof, rustproof, and industry calibrations for boat parts and jet engines. For exceptionally fabricated shims and washers with reliable modifications for durability and precision standards set to your requirements and timetables, contact our professional staff online at www.phoenixspecialty.com, or call us toll free for a free product estimate at (800) 845-2813.


¹ http://www.webcitation.org/5n9N9dsGV

²http://www.nsrp.org/3-RA Panel_Final_Reports/2011_Improved_Bonding_and_Grounding_Final_Report.pdf


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