The SCI ball screw uses an internally recirculating, cylindrical single nut without a mounting flange. Its round nut body can be integrated into a separately designed nut housing, making SCI suitable for mechanisms where a conventional flanged nut does not match the available installation structure.
DLY SCI models cover nominal screw diameters from 16 mm to 80 mm, with 4 mm, 5 mm and 10 mm lead options. The standard configuration is a C7 rolled ball screw. C5 ground accuracy can be confirmed for applications with higher positioning requirements.
Cylindrical Nut Without a Flange
The defining feature of the SCI series is its round, non-flanged nut body. Unlike an SFI or SFU nut, SCI does not use a front flange with mounting holes. The machine structure must therefore provide a suitable nut housing or retaining arrangement based on the nut outside diameter and length.
The internal return path keeps the ball circulation components within the cylindrical nut body. This avoids the external return tube found on some other ball screw nut structures and maintains a regular round outer profile.
Round cylindrical nut without flange mounting holes.
The ball return path is contained inside the nut body.
Some models have more than one nut outside diameter.
SCI Ball Screw Specifications
| Model | Diameter d (mm) |
Lead l (mm) |
Nut OD D (mm) |
Nut Length L (mm) |
Circuits N |
Dynamic Load Ca (kgf) |
Static Load Coa (kgf) |
Stiffness K (kgf/μm) |
|---|---|---|---|---|---|---|---|---|
| SCI1604-4 | 16 | 4 | 30 | 40 | 4 | 640 | 1,340 | 16 |
| SCI1605-4 | 16 | 5 | 28 / 30 | 45 | 4 | 780 | 1,790 | 20 |
| SCI2005-4 | 20 | 5 | 34 | 45 | 4 | 1,130 | 2,380 | 25 |
| SCI2005-4 | 20 | 5 | 36 | 45 | 4 | 1,130 | 2,480 | 25 |
| SCI2505-4 | 25 | 5 | 40 | 45 | 4 | 1,280 | 3,110 | 35 |
| SCI2510-4/2 | 25 | 10 | 40 | 54 | 4 | 760 | 1,950 | 31 |
| SCI2510-4 | 25 | 10 | 40 | 85 | 4 | 1,944 | 3,877 | 33 |
| SCI3205-4 | 32 | 5 | 46 | 45 | 4 | 1,450 | 4,150 | 40 |
| SCI3205-4 | 32 | 5 | 50 | 45 | 4 | 1,860 | 4,750 | 40 |
| SCI3210-4 | 32 | 10 | 50 | 85 | 4 | 3,390 | 7,170 | 40 |
| SCI4005-4 | 40 | 5 | 63 | 45 | 4 | 1,610 | 5,330 | 49 |
| SCI4010-4 | 40 | 10 | 62 / 63 | 85 | 4 | 3,910 | 9,520 | 50 |
| SCI5005-4 | 50 | 5 | 72 / 75 | 45 | 4 | 1,730 | 6,763 | 60 |
| SCI5010-4 | 50 | 10 | 72 / 75 | 85 | 4 | 4,450 | 12,500 | 65 |
| SCI6310-4 | 63 | 10 | 85 / 90 | 85 | 4 | 5,070 | 16,600 | 80 |
| SCI8010-4 | 80 | 10 | 105 | 85 | 4 | 5,620 | 21,300 | 90 |
Dimensions are in millimetres. Ca and Coa are stated in kgf; stiffness K is stated in kgf/μm. Where more than one nut outside diameter is shown, confirm the required variant before ordering.
Understanding SCI Model Numbers
The first four digits normally identify the nominal screw diameter and lead. For example, SCI1605 represents a 16 mm screw diameter and a 5 mm lead. The suffix identifies the ball circuit configuration.
Nut outside diameter is not always determined by the model number alone. SCI1605-4, for example, is listed with both 28 mm and 30 mm nut outside diameters. SCI2005-4, SCI3205-4, SCI4010-4, SCI5010-4 and SCI6310-4 also have dimensional variants. The nut drawing must therefore be checked when matching an existing housing.
SCI Compared with a Flanged Nut
SCI is selected when the machine uses a cylindrical nut housing instead of fixing the nut through a flange. If the assembly requires a front flange with mounting holes, the SFI ball screw is the more relevant series to compare.
A matching screw diameter and lead do not make SCI and SFI nuts directly interchangeable. The nut body, installation method and mounting dimensions must all correspond to the machine structure.
Accuracy and Materials
- Standard accuracy: C7 rolled ball screw.
- Optional accuracy: C5 ground ball screw, subject to model confirmation.
- Screw shaft material: S55C.
- Ball nut material: 20CrMo.
- Nut structure: Internally recirculating cylindrical single nut.
- Thread direction: Right-hand thread is standard.
SCI Model Confirmation
Confirm the complete model, screw diameter, lead, nut outside diameter, nut length and housing dimensions before selection. Load rating, stiffness, operating speed, stroke and required service life should also be considered when checking whether a model is suitable.
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