5 Common Issues Solved by Spindle Grinding

Spindle grinding is a detailed process where the spindle bearings and housing are finely ground to match tight tolerances. This process helps extend the spindle’s life, improves operational accuracy, and resolves common issues, including:

1. Taper Wear & Damage

Over time, spindle tapers will wear down. As they wear down, they lose their ability to hold tools securely and accurately, resulting in poor machining quality, increased chatter, tool damage, and misalignments.

Grinding is often the solution when taper wear occurs. During grinding, any imperfections are machined to allowable tolerances. This process restores the taper’s angle and dimensions, ensuring it can securely and accurately hold tools again.

2. Runout

When runout occurs (when the spindle or tool can’t rotate perfectly true to its axis), the quality of the final product is always at risk. Even slight runout can lead to significant issues, such as uneven tool wear, poor surface finish, and reduced accuracy.

There are two forms of runout: axial (affects the tool’s movement along its axis) and radial (the tool’s rotation around the axis). Grinding can be used to mitigate both forms. When a spindle shows signs of runout, it’s often related to wear or damage to its bearings, which helps align the spindle’s rotational axis with its central axis.

While these bearings could be replaced, grinding can be more cost-effective and minimize downtime. It can also be useful if the original bearings are custom to the machine’s design and are not readily available for purchase. When the bearings are being ground, any geometrical inaccuracies and surface finish imperfections are resolved while preserving any custom features.

3. Bearing Seat Damage

If any issues occur with the bearing seat, they often result in bearing misalignments, increased vibration due to the bearings no longer being held securely, and decreased accuracy since precision is heavily influenced by the stability and alignment of the spindle.

Like the other issues, grinding removes imperfections in the bearing seat to ensure it has the dimensions needed to hold the bearings. Then the bearing seat is finished—if the surface isn’t smooth, it could cause abrasive damage to the bearings.

4. Surface Degradation

The spindle’s surface (particularly where tools are clamped) has to maintain high dimensional and surface integrity, otherwise, it can lead to tools slipping or not being held securely during operation, increased vibration, and tool misalignments.

Spindle grinding helps restore the spindle’s original geometrical specifications, removes damage, scoring, or other irregularities, and smooths out surface imperfections.

5. Vibration & Noise

While some noise is expected during machining, excessive noise (coupled with vibration) is generally not a good sign, often indicating imbalances or surface imperfections. When left unchecked, this can lead to inconsistent cuts, poor finish quality, premature tool wear, and out-of-spec parts.

Rather than replacing the spindle entirely, grinding can be utilized to smooth out these surface imperfections, correct imbalances through a controlled process of material removal, and restore geometric accuracy.

Do You Need Spindle Grinding?

If you’ve noticed tool imbalances, load failures, faulty clamping, or other issues with your spindle, contact Superior Spindle. We specialize in repairing and restoring spindles from all major brands/manufacturers, including Kessler, Mazak, OKK, and Setco. We provide standard (10 to 14 business days) and expedited (1 to 3 business days) to help reduce downtime and ensure quality by following a strict ISO-certified repair process.

Our services include DIN standard taper grinding, vibration analysis, reverse engineering, and more. Our U.S.-based machine shop features equipment capable of holding tolerances to one micron, and we provide thorough inspections with our ABTech Microform test stand to ensure that repaired and restored spindles meet or exceed OEM performance specifications.

Contact us today to request a quote. To ensure a more efficient process, please fill out our Incoming Spindle Alert Form.