After careful and in-depth analysis of the specific market segment of machine tools, FARO has decided to design and manufacture a new bearing characterized by very high rotation speed with regard to the extremely big sizes (diameter of 1990 mm). Thanks to the performed studies, FARO staff has identified the best materials and treatments for single components.
For what concerns the bearing washers, the research of steel has led to choose a 42CrMo4, according to the codification of the reference EN 10083-3 regulation. A material that features characteristics of high hardenability, good heat resistance, excellent forging and good machinability.
The importance of the raw material and design
Bearing features have been enhanced by the special induction heat treatment, then improved by a specific quite articulated machining cycle due to the large size, which has anyway allowed achieving the expected results.
For the production of the cage the most suitable material, after proper thorough analyses, turned out to be Ergal 7075. An aluminium alloy that has the peculiarity of having excellent mechanical resistance along with a very low specific weight.
The cage is further characterized by a very specific design, optimized to minimize the contact areas between the cage itself and the shaft, and those between the cage and rolling elements.
Certified reliability and performances for a high-quality bearing
In this sector, FARO manufactures also super-precision bearings that can support both radial and axial loads and clearance free overturning moments. They are particularly suitable for supporting systems with high operating accuracy, as for example rotary tables.
For these bearings, FARO has decided to certify some technical specifications at the testing bench. The testing bench has been fully designed and realized by FARO engineers, then customized and able to offer an additional service to customers. In fact, besides the usual origin, dimensional and geometrical certifications, FARO certifies the minimum torque moment to rotate the bearing.
After fixing the bearing on the measuring plate, simulating the actual assembly, the operator can choose through the Plc panel the test torque, that is to say the value of start torque, the maximum one, the increment and decrement rate. The system determines the inner ring rotation through a stepping motor with reducer, keeping the work torque controlled. On the outer ring is positioned a load cell which, collecting data up to 5,000 times per second, reads the torque value.
Such data are registered on file and can eventually be visualized also on video and synthesized in a graphic report. In that way, it is possible to assess the stability of the bearing working torque and assure is vibrations and/or noises free. The collected data are enclosed to the testing certificate, provided for each bearing.
