Toolholding Solutions

Concentricity and Balance


The critical criteria for selection of tooling for higher speeds are concentricity and balance.


Tools should be selected based on there ability to hold the tool concentric to spindle rotation. This normally results in tools that are friction driven, such as collet chucks, shrink fit holders, power milling chucks, HP Chucks, etc.


The effect that un-balance will have on a cutting operation is relative to the type of cutting forces generated in the cut. The higher the cutting forces the less effect balance will have on the overall operation of the machine tool. Under most circumstances a pre-balanced holder is all that is required to achieve a balanced machining condition.

Selecting the proper tool holder type for higher speed applications:

ER Collet Chuck:

For most drilling and lighter higher speed milling applications. Very good concentricity and very good balance. Safe operational speed as high as 30,000 rpm. Larger sizes have a limit based on centrifugal forces.

Shrink Fit Holders:

For nominal size drilling with higher speed and higher feed milling applications. Excellent concentricity and excellent balance. No moving features, and thin nose diameters, make it exceptional for high speed machining. Safe operating speeds are extremely high due to little impact from centrifugal forces.

Power Milling Chucks:

For precision in moderate and lower speed milling and nominal drilling applications. Very good concentricity and good side load capability. Movable large clamping nut restricts the balance and centrifugal force capability, limiting the speed to 8,000 to 12,000 rpm.

Single Angle Collet System:

For heavy drilling and some milling applications. The system provides good concentricity and good grip force. The nut system does not lend itself for good balance considerations at higher speeds.

Double Angle Collet System:

For smaller drilling application where clearance is necessary. The system is the simplest to use but lacks the characteristics for concentricity and grip force. Not suitable for precision high speed applications.

Weldon End Mill Holders:

For heavy machining using tools with Weldon flats. The side lock design compromises concentricity and is not useable in higher speed applications. The positive drive of the screw is unmatched for force to prevent slippage and pull out in heavy roughing applications.