Slotted Shims
Introduction to Slotted Shims
Slotted shims, also known as horseshoe shims or slotted motor shims, are versatile, thin, rectangular shims with a slotted opening that provides an effective means of installment without having to alter the shim. These shims are invaluable tools used in assembling machine components to achieve precise alignment and balance to preserve the integrity of the machine. Metal slotted shims feature a u-shaped opening which allows them to be fitted around existing bolts and screws or utilized as regular spacers. Some varieties of slotted shims even feature tabs for simplified insertion.
Application Considerations
When using slotted shims, there are several key considerations to keep in mind:
- Load Distribution: Distribute the load evenly across slotted shims to avoid localized pressure points, which can lead to instability or misalignment.
- Corrosion Resistance: Evaluate the environmental conditions of the application (weather, chemical exposure, lubrication, etc.) to ensure your shim's material will withstand any corrosive elements. Stainless steel is well suited to resist several types of corrosion.
- Tab Usage: If using slotted shims with tabs for insertion, align them properly with the corresponding components to facilitate quick and easy installation.
- Gap Thickness: Depending on the thickness of the alignment gap, you may need a feeler gauge to measure the distance and ensure the correct shim size. Feeler gauges feature thin metal leaves that measure minute spaces as small as 0.001" in. to help you narrow in on precise sizing needs.
Benefits
Using slotted shims provides several notable advantages, including:
- Alignment Precision: Slotted shims offer a practical solution for achieving precise alignment in machinery and assemblies without the need for custom modifications.
- Time and Labor Savings: Since the u-shaped slot quickly slides around installed fasteners, these shims reduce the time and labor required for customizing a precise alignment.
- Prevent Damage: Ensuring proper alignment with precision shims like these can prevent costly damage to valuable equipment.
- Adjustable Alignment: Slotted shims provide consistent alignment, allowing for easy adjustments and modifications when needed.
- Easy Leveling: Slotted shims simplify the leveling process and provide a hassle-free way to balance components, as long as the shim properly supports the weight of the application.
How to Measure Slotted Shims
Slotted metal shims measurements include their thickness, overall width, slot width, overall length, and the slot length (or depth). Some shims feature a tab at the top that physically adds length, but this addition is not factored into the technical measurements.
When it come to the slot dimensions, it is important to note that the width indicates the distance between the small, internal u-shape, not the tapered opening. Also, the slot length applies to the entire length, not just the u-shape.
Difference Between Slotted Shims and Arbor Shims
The most obvious difference between these two types of shims is their shape -
arbor shims look like washers, while slotted shims have a rectangular body and a u-shaped slot down the middle. However, there are a few other key differences:
- Materials: Both types of shims are available in stainless steel, but arbor shims are also available in carbon steel and plastic.
- Precision: Arbor shims are machined to specific tolerances for precision alignment.
- Ease of Use: Slotted shims can be installed without disassembling the host component - this would be required to use arbor shims.
Each type of shim offers its own advantages, and you should evaluate the needs of your application before choosing the right one.
Types of Shims
Other than slotted and arbor, there are two other types of metal shims that may be helpful in your machinery applications:
- Variable Shims: Named for their ability to shorten or lengthen (depending on the type) the shaft of a mating bolt
- Shim Rings: Used to tightly hold bearings or with retaining rings to take up play between components