Spindle Balancing: Your Complete Machine, Equipment & Process Guide

As spindle speeds increase, having a well balanced spindle is becoming more important. What feels like only a few years ago, a spindle that ran 20,000 RPM seemed untouchable. Today, we see spindles that run anywhere from 60,000–150,000 RPM on a regular basis. At speeds this high, even the smallest imbalance can cause excess vibration and lead to a catastrophic spindle failure.

Regardless of RPM, a properly balanced spindle can achieve the following:

• Enhanced machine accuracy and efficiency
• Decreased noise and vibration levels created by machine tools during operation
• Longer tool life due to decreased vibration
• Good surface finish; an unbalanced machine will result in a very uneven finish
• Increased life of related components such as bearings

Balancing should only occur at the time of a rebuild; if re-balancing is necessary following a recent repair, then there are more significant issues at stake.

Spindle imbalance occurs when a spindle’s center of mass is not aligned with its center of rotation. This will cause the energy created from the imbalance to transfer to the tool and work piece. There are many factors that can cause a spindle to lose its balance, either immediately or over a long period of time. Fortunately, spindle imbalance is usually avoidable (see below).

Causes of spindle imbalance include:

• Poor/worn tooling interface causing runout or tool rocking
• Thermal fluctuation
• Improper/inattentive maintenance
• Spindle crashes
• Material build-up
• Incomplete spindle rebuild
• Misalignment from improper installation
• Additional pieces added to the rotating components without rebalancing as an assembly

Signs that a spindle is losing balance include visual “wobble,” audible tool chatter, and noticeably degraded part finish. Balance can be maintained with proper machine maintenance and cleaning protocols.

Typically, balancing equipment will have a vibration sensor placed on the spindle housing. With the spindle running, the balancer can detect both the amount of imbalance as well as the position of maximum imbalance.

At Northland Tool and Electronics we have specialized equipment to balance a variety of spindles, including:

• 2 Balmac Portable Balancers
• 4 Schenck CAB
• 2 GTI I Rotor balancer
• 2 GTI Bal Pro
• 1 Warner Swasey

Spindle balancing should only be performed by the spindle rebuilder or the OEM using the appropriate equipment. Balancing is not a maintenance service.

Spindle balancing is a necessary part of rebuilding, which is why it’s best to contact an experienced professional with the correct equipment and expertise. At Northland Tool and Electronics, we have over 40 years of experience addressing balance and other spindle issues. Give us a call or send us a note today, and we’ll be in contact soon.