Shim Installation Guide: Shimming Best Practices for Precision & Vibration Control
Struggling with machine vibration, misalignment, or instability? The secret often lies in proper shimming.
This practical shim installation guide walks you through industry-proven shimming best practices to ensure your industrial equipment runs smoothly, accurately, and reliably.
Safety First: Handle Shims Safely
Before any shimming work begins, prioritize safety:
- Always use the safety pull tab (if present) to handle shims—never touch sharp edges directly.
- Ensure the pull tab is flush with or recessed below the baseplate after installation to avoid snagging hazards.
- Never place your fingers under a raised machine foot—use lifting tools or supports.
- Clean the underside of the machine foot thoroughly with a stiff brush to remove rust, paint, oil, or debris before inserting shims.
√ Pro Tip: Dirty or uneven surfaces compromise shim effectiveness and lead to premature failure.
Choose the Right Shim Material
Material selection directly impacts performance in harsh industrial environments:
- Stainless steel shims are ideal for high-load, corrosive, or high-temperature applications.
- Slotted or pre-cut shims allow easy insertion around anchor bolts without disassembly.
- High-performance polymer shims (e.g., PTFE, PEEK, or fiberglass-reinforced composites) offer corrosion resistance and electrical insulation.
- Never reuse damaged shims—discard any that are bent, corroded, cracked, or deformed.
- If cutting custom shims from sheet material, deburr all edges to prevent injury and ensure flat contact.
How to Choose the Correct Shim Size & Thickness
Selecting the right shim isn’t guesswork—it’s engineering:
- Assess the load zone around each anchor bolt.
- Consider machine weight, horsepower, and dynamic forces.
- Match shim dimensions to the foot size and bolt slot clearance.
- Use a micrometer to verify actual shim thickness—don’t rely on nominal values.
Shim Stacking Guidelines:
- Limit total shims under one foot to no more than 4 pieces.
- Apply the “sandwich method”: place thinner shims between thicker ones to protect them from buckling or shifting.
- Avoid excessive stacking—it reduces stability and increases compliance.
Search Intent Note: Users often search “how many shims can I stack?” or “shim thickness tolerance”—this section answers those directly.
Shim Installation & Alignment Techniques
Precision installation ensures long-term reliability:
- Slide the shim set fully under the machine foot until it contacts the anchor bolt.
- Pull back slightly (1–2 mm) to avoid pinching or tearing the shim during bolt tightening.
- Torque the anchor bolts to manufacturer specifications using a calibrated wrench—uneven torque causes distortion.
Special Cases: Angled or Irregular Feet
- For stepped, curved, or uneven machine feet, use step shimming:
- Place a primary shim pack under the main contact area.
- Add a secondary offset shim on top to fill the gap at the raised edge.
- Keep the total number of shims in the stepped section ≤4, and trim any overhang flush with the foot.
Why It Matters: Proper shimming minimizes vibration, prevents bearing wear, and maintains laser alignment accuracy over time.
Final Checklist: Shimming Best Practices Summary
| Do’s | Don’ts |
|---|---|
| √ Use clean, flat, undamaged shims | ✘ Reuse bent or corroded shims |
| √ Limit stacks to 4 shims per foot | ✘ Stack thin shims on top (they buckle!) |
| √ Deburr custom-cut edges | ✘ Force shims into tight spaces |
| √ Torque bolts evenly & to spec | ✘ Ignore surface cleanliness |
| √ Trim excess material flush | ✘ Leave pull tabs protruding |
Why Proper Shimming Matters
Correct shim installation isn’t just about leveling—it’s critical for:
- Reducing vibration and extending bearing life
- Maintaining precision alignment in pumps, motors, and turbines
- Preventing foundation fatigue and bolt loosening
- Complying with ISO 8820 and ANSI/API machinery standards
Ready to improve machine reliability? Follow these shimming best practices, and turn a simple shim into your most powerful tool for precision and performance.