Shim

How to Choose the Right Mechanical Shim

In machinery maintenance and assembly, mechanical shims are small components with a big impact. However, when faced with numerous options in materials, thicknesses, or manufacturing standards, many people still wonder: “Which type is truly suitable?”

This article will answer the most common questions about selecting mechanical shims. By the end, you will clearly understand each factor to consider, avoid mistakes, and know how to choose the right product that is accurate, cost-effective, and efficient.

What is a mechanical shim and what role does it play?

Mechanical shims are thin, flat pieces, usually made of steel, copper, or engineering plastics. They are placed between components to adjust clearances, maintain alignment, reduce vibration, or increase precision during assembly.

In practice, using shims correctly helps machines run more smoothly, reduces wear, minimizes shaft misalignment, and extends equipment lifespan.

Shim materials: which type should you choose for your working environment?

Stainless steel: for harsh environments, highly resistant to corrosion, commonly used in heavy industry.

Copper/brass: wear-resistant with good electrical and thermal conductivity, often applied in electrical or thermal systems.

Engineering plastics: insulating, vibration-reducing, suitable for office machinery or lighter environments.

Practical example: The BEGA Shim set at EMIN offers a full range of options in both material and standard sizes, allowing engineers to easily choose the right shim for each application without wasting time on manual fabrication.

What shim thickness is appropriate?

Thickness directly determines alignment accuracy. A shim that is too thin may deform under load, while one that is too thick can cause imbalance and uneven stress.

A commonly applied rule: accurately measure the clearance to be adjusted, then add 10–15% to the thickness so the machine has operating tolerance and does not work under strain.

Can shims be reused?

This is a very common question. In theory, metal shims can be removed and reinstalled. However, after prolonged loading, they can deform or wear, leading to a loss of precision. Therefore, in high-accuracy applications (e.g., motor shaft alignment), engineers often replace shims instead of reusing them.

With standard pre-packaged shim sets like those from BEGA, replacement is quick and does not disrupt production.

Conclusion

A small shim can determine the stability of an entire system. Understanding material, thickness, load capacity, and manufacturing standards will help you choose the right shim that ensures performance while saving on maintenance costs.

For certainty, choose products from reputable suppliers such as EMIN. We always have a wide range of standard shim sets available, suitable for both production and maintenance.