Общий каталог Kemmler 2020 - страница 731

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 tool holder was only half the weight, i.e. 0.5 kg, the permissible counter balancing tolerance is also halved. Aim of counter balancing is to find a compromise between the technically feasible and the economically efficient. Because the radial inter- change 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 different counter balance qualities G relative to the maximum operating speed. Fine-balanced with Pre-balanced with Pre-balanced with balancing bores in the flange balancing bores at the collar balancing flat at the tool body 14 2020 14.36