UKF Spindles – Bearing Expertise Meets Spindle Technology
UKF – Berlin-based precision engineering expertise since 1932
Universal-Kugellager-Fabrik GmbH was founded in 1932 in Berlin-Charlottenburg by Max Staub and Paul Brühl. The starting point was a newly developed split ball bearing that could replace seven different types of angular contact ball bearings. A compact innovation with a major impact.
From there, UKF continued to evolve steadily, moving from individual bearings to bearing assemblies and ultimately to complete spindles. Today, the company remains headquartered in Berlin, is part of the DKF Group, and supplies customers in the machine tool, aerospace, and measurement technology industries. Customers include Airbus, Bosch, Continental, Volkswagen, Siemens, Zeiss, and the German Aerospace Center (DLR). UKF is certified to DIN ISO 9001 and handles both development and manufacturing in-house. The expertise gained from bearing manufacturing forms the foundation of its spindle design.
In-house-developed bearings as a technical advantage
Manufacturers who build spindles based on their own bearing technology have complete control over the central functional element of every spindle unit. UKF relies on self-developed angular contact ball bearings with a contact angle of 21 degrees. This design enables high axial load capacity combined with high limiting speeds. High-precision bearings with a radial runout error of less than 1 µm for smaller bore diameters are standard.
The product portfolio includes belt-driven milling, turning, and grinding spindles, as well as motorized spindles for milling, turning, and grinding applications, and geared spindles. Tool holders ranging from SK 25 to SK 50 and HSK A 40 to HSK 100 are supported. The range is complemented by custom-designed special-purpose spindles.
Structure and Design Features
Every UKF spindle is systematically designed around its own bearing technology. Key components include UKF spindle bearings with a 21-degree contact angle, the rotor and stator in motor spindles, cooling and lubrication systems, hydraulic or electric tool clamping systems—including HAINBUCH clamping systems—as well as the respective tool interface in SK or HSK configurations.
Key features include the UKF steep-taper face-contact system and the split spindle shaft. The face-contact system prevents the tool from seizing at high speeds due to shaft expansion. Spacer discs on the spindle shaft enable a dual-contact system without requiring modifications to standard tool holders.
The split spindle shaft allows a worn HSK mounting section to be replaced directly in the machine without having to remove the entire spindle. This significantly reduces downtime.
Requirements in practical use
UKF spindles are designed for demanding applications, whether it involves high cutting forces during milling and turning, tight tolerances in the grinding process, or high speeds when drilling small holes. Typical wear points include the spindle bearings, the tool holder, and—in the case of motor spindles—the stator and rotor.
Collision damage to the split shaft can be repaired cost-effectively due to its design, but requires professional inspection and realignment. Deviations in concentricity, increased vibrations, or rising temperatures should be checked promptly, especially during grinding operations, as any bearing play is directly transmitted to the workpiece surface.
Kern Spindle Service for UKF Spindle Repairs
KERN Spindle Service provides professional repairs for UKF spindle units, whether they are motor spindles, grinding spindles, or gear spindles. Our services include bearing diagnosis and replacement, inspection and reconditioning of the tool holder, verification of shaft geometry—including runout measurement—and a final test run.
Experience has shown that a repair by KERN is 20 to 30% more cost-effective than purchasing a new spindle. The turnaround time is 6 to 8 business days. We provide a 24-month warranty on every repair.
Do you need assistance with your UKF spindle?