Innovations for high precision rotary tables and rotary axes

Schaeffler offers a highly specialised modular system that allows customers to select exactly the right components for their rotary tables and rotary axes – which includes high speed, high performance and high precision designs. Schaeffler also presented new products for this modular system at EMO 2017: rotary table bearings with increased performance and extremely smooth running torque motors.

Virtually no other type of electric drive exists in which the motor and supporting bearing have so much influence on each other as in driven, high precision rotary tables and rotary axes. This is due to the very compact dimensions involved, the three heat sources (rotor, stator and bearing) are very close together, which means the heat transfer and heat dissipation must be very specifically configured to ensure optimum functionality. The rigidity of the bearing support and the machining forces also directly influence the air gap between the stator and the rotor. Because of these close functional dependencies between the motor and bearing, the components must always be developed as a customer-specific system.

Three standard torque motor series from Schaeffler’s subsidiary INA Drives & Mechatronics (IDAM) and three series of rotary table and rotary axis bearings from Schaeffler can be combined as desired, enabling the user to apply exactly the right solution for every machining process – whether it’s combined soft turning and milling, plane milling, gear grinding, grinding and hard turning, spindle applications, positioning tables, or swivel-type axes for ultra-precise machining. This optimum combination of components is adjusted by Schaeffler’s engineers to match each individual customer’s cutting process to deliver the required precision and dynamics.

Torque motor series RIB, RKI, and SRV

Torque motors in the RIB series are suitable for extremely dynamic movements and precise positioning. Ideal applications for these motors include rotary tables, axes for rotary vibration tables, and milling heads for highly dynamic and powerful milling, positioning, clocking and swiveling.

The RKI-series of motors, which differ from the standard RI series mainly due to their innovative rotor design, produce significantly greater power outputs with 30% more force, increased torque and higher speeds. These motors offer a very favourable combination of a high power yield, very good uniform running characteristics, and low power loss. Ideal applications include rotary tables with optional turning operation and rotary tables for combined milling, turning, hard turning, or grinding.

The new SRV series of torque motors stand out due to their extremely smooth running characteristics and allow high quality surfaces with outstanding form and dimensional accuracy to be achieved without optical defects. SRV motors are therefore ideal for use in ultra-precise milling, grinding, and gear cutting machines, particularly as drives for rotary tables and rotary axes with very high speeds and tool or workpiece spindles (up to 14,000 rpm).

Rotary table bearing series YRTC, YRTS, and ZKLDF

Schaeffler has an extraordinarily large range of rotary table bearings for each application’s preferred machining process, axis type, size, cutting force, and speed range. The two YRTC series of axial-radial cylindrical roller bearings – which are now available in X-life quality and a YRTS (S = Speed) version – and the ZKLDF series of axial angular contact ball bearings, represent the broadest range of products for rotary tables and rotary axes on the market. Furthermore, these bearings are also geometrically interchangeable, which can be a major advantage during the development phase.

Another major advantage is the integrated measuring system, which can be selected as an option for all rotary table bearings. The new YRC bearings are particularly suitable for use in plane milling machines and in positioning and swivel-type axes that are subjected to high loads. YRTS axial-radial bearings are the perfect solution for ultra-precise milling, grinding, and gear grinding machines, particularly as drives for rotary tables and rotary axes with very high speeds. The application of choice for ZKLDF axial angular contact ball bearings are bearing supports that have a long operating duration in rotary tables with a main spindle function (e.g. for combined milling and turning operations), bearing supports in milling, grinding, and honing heads, and in measuring and testing equipment.