6 Best alignment shims for industrial machinery Pros Use

Precision alignment is the foundation of any long-term industrial installation. When a motor and pump shaft are out of tolerance, the resulting vibration will shred seals, cook bearings, and compromise the structural integrity of the base. Selecting the right shim isn’t just about filling a gap; it’s about choosing a material that maintains its thickness under heavy, constant mechanical load. Reliable alignment eliminates the common stresses that lead to premature equipment failure in the field.

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Precision Brand Slotted Shims: The Industry Standard

Precision Brand shims are the go-to for veteran millwrights because of their unwavering consistency. These stainless steel shims offer precise thickness control, ensuring that every bolt receives the exact lift needed to bring a machine back into factory tolerance.

The slotted design allows for quick installation around existing anchor bolts without the need to fully remove hardware. This saves significant labor time during critical maintenance windows.

If the equipment is high-speed or prone to heavy thermal expansion, these 300-series stainless steel shims are the safest bet. They resist corrosion and deformation, keeping the alignment locked in regardless of the humidity or heat levels in the shop.

Accu-Trak Pre-Cut Shims: For Speed and Accuracy

Speed matters when a production line is down and every hour of downtime hits the bottom line. Accu-Trak shims are designed for high-efficiency environments where speed must be balanced with absolute accuracy.

These shims feature clearly marked sizes, which eliminates the guesswork that leads to “fiddling” during an alignment job. When moving through a large multi-motor sequence, having these pre-organized makes a massive difference in staying on schedule.

Because they are precision stamped, there are no burrs to throw off the elevation. Always double-check the bolt size to ensure the slot clearance is correct before beginning the installation.

Vibralign T-Shims: Best for Tough-to-Reach Spots

T-Shims are engineered specifically for those cramped, awkward positions where a standard shim is impossible to slide into place. The unique “T” shape allows for easier manipulation in tight motor bases or confined mechanical rooms.

These are particularly effective when the bolt pattern is obstructed by piping, electrical conduits, or narrow frame rails. Instead of struggling with a square edge, the T-handle geometry provides the grip necessary to seat the shim perfectly under the foot.

They are rugged enough to handle the torque of heavy-duty industrial fastening. If the alignment task involves tight clearances, skip the standard shims and reach for the T-style.

Lawton Shims Assortment Kits: Ultimate Versatility

When the precise gap requirement is unknown until the machine is opened, an assortment kit is a mandatory part of the tool chest. Lawton kits provide a complete range of thicknesses, allowing for granular adjustments during the alignment process.

Keeping a full kit on hand prevents the frustration of stopping a job to source a specific shim size. These kits typically offer a professional-grade selection that handles everything from fine tuning to major base adjustments.

Invest in a durable, locking organizer case to keep these sorted. If the shims become disorganized or damaged, the time lost hunting for the right thickness will quickly negate the cost savings of the kit.

Sim-Shims Color-Coded Plastic: Non-Conductive Jobs

Plastic shims serve a very specific niche where galvanic corrosion or electrical conductivity is a legitimate risk. In environments where motors must be electrically isolated, color-coded plastic shims prevent the metal-on-metal contact that facilitates current flow.

Beyond the electrical benefits, these shims are extremely lightweight and simple to trim to size with a pair of snips. They are perfect for lighter-duty machinery or specific non-conductive mounting requirements.

However, be cautious about using plastic in extremely high-heat zones or under massive compressive loads. While modern plastics are durable, they do not possess the same infinite life cycle as hardened stainless steel.

The B.A. U-Shim: Heavy-Duty Motor Base Alignment

The B.A. U-Shim is the heavyweight champion for massive motor bases where support area is critical. These shims provide a wide surface area that distributes the load evenly across the machine foot.

By using a wider U-shim, the base remains stable and avoids the point-loading that can lead to bent bolts or cracked concrete pads. They are specifically crafted to withstand the high vibration and torque found in large-scale industrial pumps and compressors.

Always ensure the base of the motor is clean and free of scale before placing a heavy-duty shim. Debris trapped under the shim will negate all precision efforts and lead to a “soft foot” condition immediately after startup.

Stainless Steel vs. Plastic Shims: What to Use

Selecting between steel and plastic is a fundamental choice based on the machine’s operating environment. Stainless steel is the gold standard for high-vibration, high-heat, and heavy-load applications.

• Stainless Steel: Use for permanent installations, high-heat areas, and heavy industrial motors.
• Plastic: Use for non-conductive needs, temporary alignments, or where chemical exposure might degrade metal.

Never mix materials under a single motor foot. Stacking plastic and metal leads to uneven settling over time, which will quickly throw the shaft alignment out of spec.

How to Measure Correctly for Your Alignment Job

Accurate measurement starts with a clean surface and a high-quality feeler gauge. If the surface of the base is rusted or uneven, a shim will never seat correctly, and the alignment will drift within hours of operation.

Clean the motor foot and the base pad with a wire brush or scraper before taking the initial reading. Use the feeler gauge to determine the exact clearance at each bolt location, recording each value with precision.

Avoid the temptation to guess or “eye-ball” the gap. Even a few thousandths of an inch can cause massive bearing wear over the long term.

Preventing Soft Foot: A Guide to Proper Shimming

“Soft foot” occurs when one of the motor feet doesn’t make solid contact with the base, leading to frame distortion when the bolts are tightened. This is the silent killer of precise alignment.

To identify soft foot, loosen the hold-down bolts and check for gaps under each corner using a feeler gauge. If a gap is present, shim that specific foot until the machine sits flat before tightening the bolts.

Always tighten the bolts in a cross-pattern to ensure even pressure. If the alignment changes after tightening, the frame is likely flexing, and more shimming at the weak point is required.

Reading Shim Markings: Size Thickness and More

Most professional shims are laser-etched with their thickness in thousandths of an inch. Understanding these markings at a glance is essential for maintaining workflow speed and accuracy.

If a shim lacks clear markings, it is a liability; discard it to prevent accidental mix-ups. Always verify the stamped thickness with a micrometer if there is any doubt about the shim’s integrity or origin.

Consistency in documentation is key. Keep a log of the shim stack used for each motor, as this will drastically reduce the time required for future maintenance and routine checks.

Proper shimming is an art form that directly impacts the lifespan of industrial assets. By choosing the right material for the load and ensuring each shim is seated cleanly, you protect the equipment from the mechanical fatigue that leads to expensive downtime. Always prioritize precision over convenience, and your machinery will reward you with years of reliable, vibration-free performance.