It is easy to confuse a basic washer with a precision spacer. Despite their visual similarities, their use cases are very different.
In this article, we’ll discuss the main differences between washers and spacers, plus questions to consider before choosing the right product for your application
The Most Common Use Cases for Washers
Washers are most typically used for fastening applications in combination with bolts and nuts. They can be used for various reasons including:
- Load distribution
- Liquid protection
- Vibration resistance
The larger surface area allows the washer to distribute forces of the bolt or nut on the mounting surface and thus reducing damage from tightening. This is the most common use case for washers and can be seen in a variety of applications.
In the case of liquid protection, whether it be keeping liquid in or out, it is important to select a washer with the appropriate hole for the bolt. This is commonly seen in internal combustion engine oil drain bolts, which are typically paired with a softer copper-based washer that deforms from tightening, providing a more complete seal to keep the engine oil in.
The best type of washer for vibration resistance is the spring washer, these come in various designs but are typically made of spring steel and provide extra axial load to increase friction and thus preventing bolts and nuts from loosening. These are typically seen in machinery where harsh vibration is common in operation.
What Are Spacers and When Are They Used
Spacers are mainly used to help locate components along an axis. This is why spacers have a larger range of inner diameters, outer diameters, thicknesses, and tighter tolerances.
Some applications for spacers include aligning sprockets, gears, or pulleys along a shaft, and to properly space out electronic circuit boards that are fastened together. Due to this customizability in dimensions, the higher tolerances, and the differences in manufacturing, spacers will generally cost more than washers.
What is the Difference Between a Spacer and a Washer?
While washers are primarily used for a more general purpose, in conjunction with nuts and bolts, spacers are often used for more specific applications where dimensions and tolerances are much more important.
Here are some main differences:
| Washers | Spacers |
|---|---|
| Standardized sizing | Creates space between objects |
| Load distribution | Highly configurable |
| Vibration absorption | Precision machined |
| Low cost | High cost |
Deciding Between a Washer or a Spacer
When deciding on whether a washer or spacer is needed for your application, it is best to ask the following questions.
- Do you need a non-standard sized thickness, or inner/outer diameter?
- Do you need tight tolerances?
- Do you require specific materials or surface finishes?
In many cases, washers will suffice. However, when there is a non-standard spec, tight tolerances or special materials needed, spacers will be needed for its high degree of configurability.
You can learn more about MISUMI’s washers and precision spacers by checking out our product comparison guide here.
