NCCER Millwright Practice Exam

Which type of shim material is used for supporting light weights with very thin requirements?

1. Steel shims

2. Plastic shims

3. Wooden shims

4. Cardboard shims

The correct answer is: Plastic shims

Plastic shims are ideal for supporting light weights with very thin requirements because they can be manufactured to precise dimensions and are available in various thicknesses. This property allows them to provide a stable, non-compressive support system that minimizes variances in height while remaining lightweight and resistant to moisture and corrosion. Plastic shims also have excellent durability, which makes them particularly suitable for applications where metal corrosion from moisture is a concern. While other materials like steel, wood, or cardboard may be employed for shim purposes, they may not offer the same level of precision, lightweight properties, and resistance to environmental factors that plastic shims provide. Steel shims, though strong, are often overkill for light applications and may add unnecessary weight. Wooden shims can be subject to variation in thickness due to changes in humidity or temperature, affecting their reliability and precision. Cardboard shims, while lightweight, may lack the necessary strength and durability for even moderate weights, making them less suitable for applications requiring thin support.