Description
SHAC SFNU / SFA Ball Screw Nuts
Precision-matched SHAC ball screw nuts for dependable CNC and automation motion
The SHAC SFNU / SFA Ball Screw Nut range combines eight right-hand models engineered for exact pairing with selected SCR and SSR rolled ball screws. Two recirculation designs, hardened internal components and integrated sealing provide a strong foundation for smooth, low-friction and repeatable linear movement in demanding machine axes.
Select by the complete nut model and matching ball screw code—not diameter and lead alone. This product includes one selected ball screw nut; the compatible ball screw is ordered separately.
Recommended purchase:
Whenever possible, order the ball screw nut together with its matching SHAC ball screw and choose installation by Vallder before dispatch. The same nominal size does not guarantee compatible raceway geometry, ball diameter, axial clearance or preload. A separately purchased nut for an existing or unidentified ball screw therefore cannot be guaranteed to fit or achieve the required backlash and preload unless the exact manufacturer, model and configuration are confirmed. A correctly matched and mounted SHAC pair is the safest and simplest choice for reliable operation.
SFNU Internal-Circulation Nuts — Drawing and Technical Data
This drawing and table cover SFNUR1605-4, SFNUR1610-3, SFNUR2005-4, SFNUR2505-4 and SFNUR2510-4. Each model is matched with the corresponding SCR ball screw listed in the table.
| Model no. | Product SKU | Matching Ball Screw | Ball Screw Specifications | Load Data | Dimensions (mm) | |||||||||||||
| Ball Screw Model | Ball Screw SKU | d | Lead | Da | dr | Ca (kgf) | Co (kgf) | D | A | B | L | W | H | X | Q | n | ||
| SFNUR1605-4 | 1258001 | SCR1605 | 1259001 | 16 | 5 | 3.175 | 13.82 | 1381 | 3055 | 28 | 48 | 10 | 45 | 38 | 40 | 6-Φ5.5 | M6×1 | 4×1 |
| SFNUR1610-3 | 1258002 | SCR1610 | 1259002 | 16 | 10 | 3.175 | 13.82 | 1104 | 2404 | 28 | 48 | 10 | 57 | 38 | 40 | 6-Φ5.5 | M6×1 | 3×1 |
| SFNUR2005-4 | 1258003 | SCR2005 | 1259003 | 20 | 5 | 3.175 | 17.82 | 1552 | 3879 | 36 | 58 | 10 | 51 | 47 | 44 | 6-Φ6.6 | M6×1 | 4×1 |
| SFNUR2505-4 | 1258004 | SCR2505 | 1259004 | 25 | 5 | 3.175 | 22.82 | 1726 | 4909 | 40 | 62 | 10 | 51 | 51 | 48 | 6-Φ6.6 | M6×1 | 4×1 |
| SFNUR2510-4 | 1258005 | SCR2510 | 1259005 | 25 | 10 | 4.762 | 21.74 | 2957 | 7302 | 40 | 62 | 12 | 80 | 51 | 48 | 6-Φ6.6 | M6×1 | 4×1 |
| All product data (pictures, dimensions, tables, drawings) are provided as received from the supplier; we exclude liability for their accuracy or completeness. | ||||||||||||||||||
Ball Screw & Stepper Motor Calculator
Use the calculator to match ball screw lead and speed with stepper motor torque, current, voltage and step resolution for your CNC axis.
SFA End-Plug Circulation Nuts — Drawing and Technical Data
This drawing and table cover SFAR1616-2.8, SFAR2010-3.8 and SFAR2020-2.8. Check the pairing carefully: SFAR1616-2.8 and SFAR2010-3.8 use SSR ball screws, while SFAR2020-2.8 uses SCR2020.
| Model no. | Product SKU | Matching Ball Screw | Ball Screw Specifications | Load Data | Dimensions | ||||||||||||||
| Ball Screw Model | Ball Screw SKU | d | Lead | Da | dr | Ca (kgf) | Co (kgf) | D | A | E | B | L | W | H | X | Q | n | ||
| SFAR1616-2.8 | 1258011 | SSR1616 | 1259011 | 14.8 | 16 | 2.778 | 12.83 | 858 | 1891 | 28 | 48 | 5 | 10 | 59 | 38 | 40 | 6-Φ5.5 | M6×1 | 2.8×1 |
| SFAR2010-3.8 | 1258012 | SSR2010 | 1259012 | 20 | 10 | 3.175 | 17.82 | 1586 | 4039 | 36 | 58 | 7 | 10 | 52 | 47 | 44 | 6-Φ6.6 | M6×1 | 3.8×1 |
| SFAR2020-2.8 | 1258013 | SCR2020 | 1259013 | 20 | 20 | 3.175 | 17.50 | 1189 | 2926 | 36 | 58 | 7 | 10 | 72 | 47 | 44 | 6-Φ6.6 | M6×1 | 2.8×1 |
| All product data (pictures, dimensions, tables, drawings) are provided as received from the supplier; we exclude liability for their accuracy or completeness. | |||||||||||||||||||
More SHAC models available:
The models shown on this page represent only a carefully selected part of the complete SHAC ball screw and nut range chosen by Vallder for common CNC and automation requirements. Vallder can also source other SHAC models and configurations from the full product range shown in the catalogue above. If the model you need is not listed, send us the exact SHAC code for an availability check and quotation.
Key Features and Applications
- Exact SHAC compatibility:
Every nut is assigned to a specific SCR or SSR rolled ball screw and a separate Vallder SKU. - Two proven recirculation layouts:
Choose SFNU internal circulation or the SFA end-plug system according to the required model and lead. - Hardened working components:
The SHAC catalogue specifies SCM415H nut material at HRC 58–62 and GCr15 balls at HRC 60 or above. - Protected operation:
Dust-proof sealing rings at both ends help protect the recirculation system from ordinary contamination. - Machine-ready flange designs:
SFNU and SFA geometries integrate into CNC carriages, nut housings and linear actuator structures.
Application:
Suitable for CNC routers, milling-machine axes, laser and plasma positioning systems, automated handling equipment, linear stages and industrial machine retrofits. Correct model matching, alignment, lubrication and environmental protection are essential for reliable performance.
Ball Recirculation Design
The two nut families use different return paths to keep the balls circulating continuously between the loaded raceway and the internal return system.
SFA End-Cap / End-Plug Circulation
Working principle:
The balls travel through several loaded turns from one end of the nut to the other. At the end, the end-cap / end-plug collects them and guides them into a return passage built into the nut body, which carries them back to the starting end for the next loaded circuit.
SFNU / SFU-Style Internal Deflector Circulation
Working principle:
Each internal deflector redirects the balls at the end of an individual circuit. The balls leave the loaded raceway, cross over the screw land through the deflector groove and re-enter the adjacent raceway, creating a compact return loop for every circulation circuit.
Choose the nut and ball screw as one exact pair. Find the required nut model in the first column, then order the ball screw shown on the same row. The product SKUs allow both components to be identified without ambiguity.
| Ball Screw Nut | Compatible Ball Screw | Nominal Size | |||
|---|---|---|---|---|---|
| Nut Model | Nut SKU | Nut Type | Ball Screw Model | Ball Screw SKU | |
| SFNUR1605-4 | 1258001 | SFNU (internal) | SCR1605 | 1259001 | 16 × 5 mm |
| SFNUR1610-3 | 1258002 | SFNU (internal) | SCR1610 | 1259002 | 16 × 10 mm |
| SFNUR2005-4 | 1258003 | SFNU (internal) | SCR2005 | 1259003 | 20 × 5 mm |
| SFNUR2505-4 | 1258004 | SFNU (internal) | SCR2505 | 1259004 | 25 × 5 mm |
| SFNUR2510-4 | 1258005 | SFNU (internal) | SCR2510 | 1259005 | 25 × 10 mm |
| SFAR1616-2.8 | 1258011 | SFA (end-plug) | SSR1616 | 1259011 | 16 × 16 mm |
| SFAR2010-3.8 | 1258012 | SFA (end-plug) | SSR2010 | 1259012 | 20 × 10 mm |
| SFAR2020-2.8 | 1258013 | SFA (end-plug) | SCR2020 | 1259013 | 20 × 20 mm |
Product models, compatibility and SKU references are based on the SHAC supplier data and Vallder product range.
Important:
Do not match components by size alone. SFAR1616-2.8 and SFAR2010-3.8 use SSR ball screws, while SFAR2020-2.8 uses SCR2020. When possible, order both components together and have Vallder mount the nut on the matching ball screw before dispatch.
Installation and Handling
- Confirm the complete pairing:
Verify the nut model, matching ball screw, diameter, lead and right-hand direction before assembly. - Use a transfer sleeve:
Keep the sleeve firmly against the ball screw thread while installing or removing the nut. - Protect the ball circuit:
Never move the nut off the threaded raceway without support; the recirculating balls may dislodge. - Maintain accurate alignment:
Align the nut housing and support units to prevent radial, eccentric or partial loading. - Test before powered operation:
Rotate the assembly manually and confirm smooth travel across the usable stroke.
Unsmooth rotation, abnormal noise or rising temperature can indicate incorrect alignment, flange runout or side loading. Ball screw nuts are designed primarily for axial force transmission.
Lubrication and Protection
Correct lubrication reduces friction, wear and operating temperature. Select oil or grease according to speed, load, duty cycle, temperature and contamination level.
- Grease maintenance:
SHAC gives two to three months as a general inspection reference and recommends annual replacement under normal conditions. - Higher-speed operation:
The catalogue generally favours oil above approximately 3–5 m/min, subject to the complete machine design. - Clean relubrication:
Remove old contaminated grease from the accessible ball screw surface before applying fresh lubricant. - Additional protection:
Use bellows, folding covers or spiral tubes in environments with substantial dust, chips, moisture or abrasive debris.
These intervals are general manufacturer guidance. Base the final maintenance schedule on actual operating conditions and inspect the system if noise, vibration, temperature or positioning behaviour changes.
FAQ frequently asked questions
Is the matching ball screw included?
No. This product contains one selected ball screw nut. The compatible SCR or SSR ball screw is ordered separately.
Can I select a nut only by diameter and lead?
No. Always confirm the complete nut model and matching ball screw code because nominally similar sizes may use different raceway geometry.
Do all SFA nuts use SSR ball screws?
No. SFAR1616-2.8 and SFAR2010-3.8 use SSR models, while SFAR2020-2.8 uses the SCR2020 ball screw.
Can the nut be removed from the ball screw?
Yes, but only with a suitable transfer sleeve. Unsupported removal can allow the recirculating balls to leave the nut.
Should I use oil or grease?
Both are supported. The correct choice depends on speed and operating conditions; SHAC generally favours oil above approximately 3–5 m/min.
Is additional dust protection necessary?
Use additional covers where substantial dust, chips, coolant or abrasive debris can reach the ball screw.
