Ball Screws with tube circulation – robust & versatile
For applications that combine high loads with great flexibility, Ball Screws with external tube circulation are the right solution for you. They feature an external return channel whose number and position can be adapted to specific requirements. This allows them to cover a wide range from light to heavy loads and provides a robust solution for universal use.
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Accuracy C5–C1
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DN value 100,000
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Universal application
How does tube circulation work?
Ball Screws with external tube circulation guide the balls back through one or more external tubes mounted on the outside of the nut. This design allows high flexibility in defining nominal diameter, lead, and the number of load-carrying ball circuits.
The number of return tubes can be adapted to the load requirements—from simple positioning tasks to highly loaded feed axes. In addition, this design enables the use of larger balls, resulting in higher load capacities.
Your benefits at a glance
Modular
Depending on the required load capacity, one or more return tubes can be arranged. The configuration (e.g., 1.5×2 or 2.5×3 circuits) can be precisely adapted to the application.
Easy to maintain
The return tube is mounted externally on the nut and is clearly visible. Contamination or damage can be easily detected, and the tube can be replaced if necessary.
Versatile
Unlike internal deflection systems, tube circulation can also be combined with large leads—covering applications from light to heavy loads.
Typical applications
The feed axes of large milling machines must transmit both high cutting forces and fast rapid traverse movements. Thanks to its robust return system, tube circulation offers high reliability even in the presence of chips and coolant.
When handling workpieces weighing several hundred kilograms, high load capacities are essential. The double nut with tube circulation (FDZG) provides high rigidity thanks to its external return system, while also offering good accessibility for maintenance.
Woodworking applications generate large volumes of chips. The external return tube of tube circulation is less prone to clogging from wood chips than integrated deflection systems, which increases operational reliability.
In linear drives that must generate high thrust forces, large-ball versions of tube circulation are often used. They provide the necessary load reserve for peak loads and ensure a long service life.
For positioning tables in heavy machinery and rolling mill applications, high rigidity and precise guidance are essential. Tube circulation with multiple return tubes (e.g., 2.5×3) is the typical choice in these cases.
Type overview
FEZG – Single flange nut with tube circulation (external return tube)
The FEZG series is a single flange nut with an external return tube. It's suitable for medium to high load requirements and is available in a wide range of sizes.
Nominal-Ø (mm)
Lead (mm)
Dynamic load rating (kN)
Static load rating (kN)
Rigidity K (N/µm)
Nominal-Ø (mm)
Lead (mm)
Dynamic load rating (kN)
Static load rating (kN)
Rigidity K (N/µm)
FDZG – Double flange nut with tube circulation (external return tube)
The FDZG series is a preloaded double flange nut with an external return tube. It's the preferred choice when high system rigidity and backlash-free positioning are required under high load conditions.
Nominal-Ø (mm)
Lead (mm)
Dynamic load rating (kN)
Static load rating (kN)
Rigidity K (N/µm)
Nominal-Ø (mm)
Lead (mm)
Dynamic load rating (kN)
Static load rating (kN)
Rigidity K (N/µm)
FEVG – Single flange nut with tube circulation (internal return tube)
The FEVG series is a single flange nut with an internal return tube. It offers a more compact design than the FEZG while providing similar load ratings.
Nominal-Ø (mm)
Lead (mm)
Dynamic load rating (kN)
Static load rating (kN)
Rigidity K (N/µm)
Nominal-Ø (mm)
Lead (mm)
Dynamic load rating (kN)
Static load rating (kN)
Rigidity K (N/µm)
Nominal-Ø (mm)
Lead (mm)
Dynamic load rating (kN)
Static load rating (kN)
Rigidity K (N/µm)
Nominal-Ø (mm)
Lead (mm)
Dynamic load rating (kN)
Static load rating (kN)
Rigidity K (N/µm)
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.