Rotating Ball Nut for long screws
With very long screws, conventional screw-driven systems reach their limits because the critical speed becomes the limiting factor. With Rotating Ball Nuts from the FEIR and FDIR series, the screw remains stationary while the nut rotates. This allows you to achieve extremely high feed speeds even with very long screws, while also benefiting from a simplified machine design.
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Accuracy classes C5 – C3
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DN value up to 70,000
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Easy installation
How does the Rotating Ball Nut work?
With very long screws (e.g. over 5 m), the permissible critical speed becomes a challenge — the screw begins to vibrate or whip. The rotating ball nut solves this problem: the screw remains stationary while the nut is driven in rotation by a separate drive system (timing belt, pinion, or direct drive). The nut converts its own rotational motion into linear movement and travels along the stationary screw.
Your benefits at a glance
Flexible
Multiple nut units can be installed on the same lead screw, each driven by separate motors.
High-Speed Transmission
In conventional drive systems, the critical speed of a long screw limits maximum velocity. By using the rotational motion of the nut, high-speed transmission can be achieved.
Simple Design
Since the lead screw does not rotate and no support bearing is required, the end design of the screw shaft is significantly simplified.
Typical applications
For very long travel distances (5–20 m), the critical speed of the screw limits maximum velocity. With a rotating ball nut, the screw remains stationary—there's no speed limitation caused by screw whipping. This enables high rapid traverse speeds and short cycle times.
In automated conveying systems, heavy loads often need to be positioned quickly over long distances. The rotating ball nut enables high speeds with a stationary screw, without requiring complex bearing support at both ends of the screw.
Multiple rotating ball nuts can be positioned independently on a single stationary screw, each with its own drive. This is ideal for assembly lines with multiple workpiece carriers or for systems that move several grippers simultaneously.
Laser cutting systems require high traverse speeds combined with high precision. The rotating ball nut reduces the moving mass inertia, enabling highly dynamic motion with smooth, stable operation.
In packaging lines, short cycle times are critical. The rotating ball nut enables linear speeds of up to 110 m/min with reduced noise levels—ideal for time-optimized production environments.
Type overview
FEIR – Rotating Single Nut
The FEIR series is a rotating single ball nut. It's designed for applications with a rotating nut and a stationary screw. The nut is driven in rotation by an external drive (e.g. timing belt).
Nominal-Ø (mm)
Lead (mm)
Dynamic load rating (kN)
Static load rating (kN)
Nominal-Ø (mm)
Lead (mm)
Dynamic load rating (kN)
Static load rating (kN)
FDIR – Rotating Double Nut
The FDIR series is a rotating double ball nut with preload. Two nuts are preloaded against each other, completely eliminating axial backlash. It's designed for the highest precision requirements in rotating-nut systems.
Nominal-Ø (mm)
Lead (mm)
Dynamic load rating (kN)
Static load rating (kN)
Nominal-Ø (mm)
Lead (mm)
Dynamic load rating (kN)
Static load rating (kN)
Design and maintenance guidelines
Design and maintenance guidelines
Materials
Our Ball Screws are manufactured from high-quality case-hardening materials. The screw shafts are made of quenched and tempered steel (according to DIN 17006: 50CrMo4 or Cf53), while the nuts are made of bearing steel (GCr15, GCr15SiMn, or 20CrMo). A precise heat treatment process ensures a consistently high hardness of the raceways of 60 ± 2 HRC.
For special requirements, e.g. in the food or medical technology sectors, stainless steel versions are also available on request.
Installation and design guidelines
To ensure optimal performance and a long service life, please observe the following points during design and installation:
- Screw end: Design the screw end so that at least one end features a full thread. The outer diameter of this end must be at least 0.2 mm smaller than the root diameter of the thread to allow mounting of the nut.
- Alignment: The screw axis must be aligned precisely parallel to the guide rails.
- Mounting position: During assembly, the nut should be positioned as close as possible to the bearing. For long-term storage, we recommend hanging the screw vertically to prevent bending due to its own weight.
- Ambient temperature: The permissible operating range is –20 °C to +80 °C.
Lubrication
Proper lubrication is critical for the performance and service life of your Ball Screw.
- Lubricant selection: The choice between oil and grease lubrication depends on speed, ambient temperature, and load. Please ensure that different lubricant types (especially greases) are not mixed.
- Grease quantity: As a guideline, fill approximately one-third of the free internal volume of the nut with grease.
- Oil quantity (guideline values): The table below shows the recommended oil quantities depending on the screw diameter. The relubrication interval is approximately 3 minutes during operation.