26 March 2025

When performing internal grinding, taper issues are among the most frequently encountered problems. Taper occurs when the bore diameter becomes progressively larger or smaller towards one or both ends, sometimes forming an hourglass or barrel-shaped profile.

Here are six effective solutions to troubleshoot and resolve taper issues:

Solution #1: Change Your Oscillation Stroke

If the bore is smaller on one end, the ends may not be exposed to the grinding wheel enough. Conversely, if the bore is larger at the ends, the center may be receiving excessive grinding. Adjusting the oscillation stroke length can resolve this imbalance.

• Increase Stroke Length: Extend the stroke further into one or both ends to ensure uniform exposure.
• Reduce Stroke Length: Minimize the stroke to reduce grinding at the ends and allow more time in the center.

Refer to the following figure for ID grinding oscillation adjustment tips.

Solution #2: Dress a Reverse Taper into the Wheel

Deflection can occur when the grinding wheel applies pressure, causing the wheel to slightly bend. This misalignment can produce taper in the bore.

• Reverse Dressing: Dress a compensating reverse taper into the wheel to counteract deflection.
• Wheel Inspection: Regularly inspect the wheel’s shape to ensure accuracy.

Solution #3: Increase Spark-Outs

Spark-outs allow time for the wheel to oscillate without feeding, relaxing accumulated forces.

• Extend Spark-Out Time: Add an extra 1-2 seconds to reduce taper by eliminating deflection.
• Monitor Results: Adjust the spark-out duration based on bore quality.

Solution #4: Retract and Regrind

For a faster alternative to extended spark-outs:

• Retract the Wheel: Temporarily pull back to release deflection forces.
• Regrind: Perform a brief regrind cycle for taper correction.

Solution #5: Sharpen the Wheel for Aggressiveness

A dull wheel causes excessive deflection. Sharpening the wheel reduces this effect.

• Aggressive Dressing: Use sharper dressing parameters to maintain wheel sharpness.
• Regular Maintenance: Ensure consistent wheel condition for optimal performance.

Solution #6: Make a Taper Adjustment on Your Machine

Some machines offer taper adjustment through work head or spindle swivel settings.

• CNC Adjustments: Use control settings for quick and precise taper adjustments.
• Manual Adjustments: On older machines, perform mechanical adjustments cautiously to avoid misalignment.

Final Thoughts

While machine adjustments can sometimes solve taper issues, addressing root causes using these best practices is preferable. Elitech Machine Tools recommends starting with oscillation adjustments and spark-outs before considering mechanical interventions. By following these solutions, you can minimize taper problems and achieve optimal grinding results.