Balancing Tools Made Easy

Unbalances in your tool quickly become a problem in several ways: They cause the tool to run out of round, put strain on the spindle and the machine, impair machining performance, and ultimately compromise the overall process reliability.

The term “unbalance” describes the ubiquitous phenomenon in rotating bodies whereby their mass is not distributed symmetrically about the body’s axis of rotation. There are essentially three types of unbalance:

• Static unbalance: Here, the center of gravity of the rotating body lies outside the axis of rotation. This can already be measured when the body is at rest.
• Couple unbalance: The center of gravity lies on the axis of rotation; the unbalance becomes measurable only when the object is in rotational motion.
• Dynamic unbalance: The term “dynamic unbalance” encompasses the other two forms of unbalance, in any combination of static unbalance and couple unbalance. This is the norm for technical rotors.

Each specific form of unbalance can be corrected by adjusting the rotating body in an appropriate manner.

During rotation, an unbalance becomes more noticeable the greater the unbalance is (linear increase) and the faster the rotational movement is (quadratic increase). The faster the rotational movement, the more important balancing becomes, and the more important it is to reduce the residual unbalance as much as possible. Balancing should therefore be systematically incorporated into the work process.

During high-speed machining of workpieces with rotating tool systems, even the slightest inaccuracy or defect in precision can, under certain circumstances, become apparent very quickly and very clearly. An unbalance in the tool can cause vibrations and will certainly result in erratic operation.

Both of these factors impair the tool’s machining accuracy and always increase the risk of defects and damage to the workpiece: surface finish deteriorates, and scrap may result. However, since your processes heavily depend on producing correctly machined end results, tools that are not precisely balanced make more extensive quality controls necessary. Rework may also be required, and in any case, process reliability cannot be guaranteed.

As a rule of thumb, therefore: It’s better to balance tools early and often than to end up paying the costs later. In general, a tool should be rebalanced whenever it is used at a different speed—because even this change can cause significant differences in how smoothly it runs.

Regular balancing increases productivity and the quality of your work.

The balancing system then uses this measurement data to calculate the required correction for the imbalance. With an advanced balancing machine, the necessary adjustments can be implemented immediately; fine balancing continues until no residual unbalance is measurable or all values fall within an acceptable tolerance range.

In this way, the process of balancing does not even take especially long, and the unevenly distributed mass can be quickly corrected.

A high-precision and largely automatic balancing system is also useful because it provides the option of repeated, quick and efficient rebalancing of tools with every changeover. This prevents quality losses caused by changes in requirements, speed, or materials, without compromising work speed.