Balancing

Especially in High-speed manufacturing there are high requirements                   
concerning the grade of balance of a toolholder.                   
KFH owns a modern digital dynamic balancing machine                   
for fine-balancing.

Unbalance

Two factors determine the unbalance of a toolholder                   
in the machine-spindle                   
                   
1. Unbalance out of un-symetric shape of the toolholder                   
                   
2. Unbalance out of not coaxial position in the spindle                   
    ( within microns )       

Unbalance occurs especially at:

- toolholders DIN 69871                    
   (Unbalance because of not symetric grooves in collar)                    
                   
- Endmillholder Weldon                    
  (Unbalance because of the clamping screw)

Limits of balancing

The reproducability of a result of balancing depends very much upon,                   
how precise the toolholder can be fitted in the spindle.                   
                   
At a common run-out of 2 microns between toolholder and spindle,                    
it is not possible to reach for example for an endmill holder                   
DIN 69871 SK40 Dia 16 x 63 a grade of balance of G2,5 at 18.000 rpm.                   
Even with a 100% free of unbalance toolholder (with total symetric shape)                   
there occurs only a grade of balance of G 4,0 (mm/s)                   
                   
Therefore it is technicaly as well as economicaly not useful to balance                   
a tool holder to G2,5.           

We recommend fine balancing beginning with 10.000 to 12.000 rpm

In the version DIN 69871 AD/B SK40 we have on stock prebalanced toolholders to G6,3 at 10.000 rpm.