Каталог ZCC-CT оснастка - страница 379

Balancing limits In accordance with DIN ISO 1940 the balance grade is denoted with G as well as the units gmm/kg or μm respectively and is relative to the number of revolutions. At a speed of 15,000 rev./min and a weight of 1 kg, G 6.3 corresponds with a permissible center deviation between rotational axis and center of gravity axis of the spindle of 4 μm. At twice the speed of 30,000 rev./min it would be 2 μm. If the toolholder was only half the weight, i.e. 0.5 kg, the permissible counter balancing tolerance is also halved. Aim of counter balancing is to nd a compromise between the technically feasible and the economically e cient. Because the radial interchange accuracy for a brand-new HSK holder can be 2 to 3 μm and for an ISO taper shank holder can be 5 to 10 μm, it means an initial quality limit of G 2.5 or G 6.3 respectively at 10,000 rev./min. The following diagram shows the quality grades to DIN ISO 1940-1, i.e. the permissible rest imbalance in relation to the balance body mass for di erent counter balance qualities G relative to the maximum operating speed. Fine-balanced with Pre-balanced with Pre-balanced with balancing bores in the ange balancing bores at the collar balancing at at the tool body i j.30