Balanceable toolholders for high speed.

The purpose of balancing a toolholder is to improve the distribution of the masses of its body so that it rotates without creating centrifugal forces above a prescribed limit.
The use of Toprun balanceable toolholders provides the following advantages:
- considerable extension of machining center spindle life;
- considerable extension of tool life;
- improved accuracy and surface finish;
- drastic reduction of vibration and noise level of the machining center.
For high speed machining with Toprun toolholders, the two counterweights in the graduated groove (patented) have to be positioned following the indications provided by the electronic balancing unit; a quick and easy balancing of the toolholder fitted with tie-rod and tool according to the ISO 1940/1 standard. For machining up to 8,000 rpm it is sufficient to position the counterweights at 0° and at 180°.


The balancing operation has the aim of reducing the original toolholder unbalance “U” within the maximum admissible level “G”. The manufacturers of high speed milling machines usually prescribe a balancing level “G 1” or “G 2.5” for the toolholders to be used on their machines according to the ISO 1940/1 standard. From the value of the maximum admissible unbalance level “G” and the spindle RPM, the value “e” can be calculated, corresponding to the balancing defect (expressed in g•mm/kg) or the toolholder runout (expressed in µm).
The patented Toprun balancing system allows a quick, easy, accurate and inexpensive achievement of high balancing standards of the toolholder, within 0.5 g•mm/kg, without any need to remove or add material. Specifically, the original unbalance “U” of the tool and toolholder is neutralized by the resulting centrifugal force “C” produced by the two balancing counterweights “T1” and “T2” of the counterweights. The advantage of this system is that the operator just needs to position the counterweights without having to make any calculations.

D'ANDREA S.p.A. Via Garbagnate, 71 - 20020 Lainate (Mi) Italy - Tel +39 02 9375321 Fax +39 02 93753240 -
P.IVA IT12213140150  Capitale Sociale € 2.100.000 i.v.  Reg.Imp. Milano n. 12213140150