DLY and HIWIN Ball Screw Model Codes: How to Compare Specifications

Ball screw model codes such as SFU1605, SFU2005 and DFU2510 appear to be simple combinations of letters and numbers. However, a complete ball screw designation may also contain information about the nut structure, ball circuits, flange machining, accuracy grade, axial clearance, preload and screw length.

The difficulty arises when comparing products from different manufacturers. DLY and HIWIN ball screw codes may describe similar basic specifications, but their series letters are not automatically interchangeable. Two nuts with the same nominal diameter and lead can still differ in overall length, flange dimensions, mounting holes, ball circulation structure and load rating.

When selecting or replacing a ball screw, the model code should therefore be used as a starting point. Final compatibility must be confirmed from drawings and operating specifications.

Ball Screw Model Code Structure

A ball screw model number usually combines a nut series code with numerical and optional technical codes. The exact order and meaning vary between manufacturers, but the following information is commonly included:

Example of the information contained in a complete ball screw designation

Code section	Typical meaning	What should be confirmed
Series letters	Nut structure or product family	Single or double nut, flange form, nut body and circulation design
First number group	Nominal screw diameter in millimetres	Nominal diameter, root diameter and shaft-end dimensions
Second number group	Lead in millimetres per revolution	Required linear speed, motor speed and positioning resolution
Circuit code	Number of loaded ball circuits or turns	Manufacturer-specific circuit definition and load rating
Accuracy code	Lead accuracy grade	Rolled or ground production method and required travel accuracy
Clearance or preload code	Axial clearance or internal preload level	Allowable backlash, rigidity, torque and thermal conditions
Length code	Screw shaft length or overall assembly length	Threaded length, usable stroke and end-machining positions

Meaning of SFU2005

SFU2005 is one of the most frequently searched ball screw model numbers. In the DLY model system, it can be read at a basic level as:

SFU - flanged single-nut series

20 - 20 mm nominal screw diameter

05 - 5 mm lead per screw revolution

A 5 mm lead means that the nut theoretically travels 5 mm for each complete revolution of the screw. At 1,000 r/min, the theoretical linear speed is:

1,000 × 5 ÷ 60 = 83.3 mm/s

The short code SFU2005 does not define the complete assembly. Ball circuit configuration, nut dimensions, accuracy, axial clearance, shaft length and end machining still need to be specified. Detailed dimensions for the DLY version can be checked on the SFU ball screw product page.

Common DLY Series Codes

The letters at the beginning of a DLY model indicate the nut family. They should be read as series identifiers rather than as a complete technical specification.

DLY series	General nut form	Main identification point
SFU	Single flanged nut	Common industrial flange-style ball nut
DFU	Double flanged nut	Two nut sections used for preload adjustment
DFI	Double-nut configuration	Different nut and flange geometry from DFU
SFA / SFE / SFY	Single-nut series with different body designs	Nut length, flange and circulation structure must be checked separately
SFNU / SFS	Alternative nut configurations	Selected according to mounting space and application requirements
SFK	Compact flanged nut	Suitable where nut installation space is limited

The series name identifies the general design family, but the dimensional drawing remains the controlling document. For example, a double-nut ball screw may be supplied in DFU or DFI form, depending on the required nut geometry and assembly arrangement.

DLY and HIWIN Code Comparison

HIWIN ball screw model code example for specification comparison

A manufacturer-specific model code should be decoded according to its corresponding catalogue

DLY and HIWIN both use model codes to describe ball screw products, but the letters and suffixes are defined within each manufacturer's own catalogue. A DLY series code should not be converted into a HIWIN series code solely by matching the letters or a general description such as "single nut" or "double nut."

The following items can normally be compared directly after their units and definitions have been confirmed:

Nominal screw diameter
Lead per revolution
Screw shaft length and usable stroke
Direction of helix
Specified accuracy grade
Axial clearance or preload requirement

Other characteristics require a dimensional drawing or technical catalogue and should not be assumed from the model code alone.

Comparison item	Can the code confirm it?	Required verification
Diameter and lead	Usually	Confirm the numerical coding rules and units
Nut outside diameter and length	No	Compare complete dimensional drawings
Flange dimensions	No	Check flange diameter, thickness, hole circle and orientation
Ball circulation structure	Manufacturer-specific	Check the series description and sectional drawing
Dynamic and static load ratings	No	Compare catalogue ratings and calculation conditions
Preload and axial clearance	Partly	Confirm the actual clearance or preload value, not only the suffix
Interchangeability	No	Verify dimensions, ratings, accuracy and installation conditions together

Replacement Example

Suppose an existing machine uses a 20 mm diameter, 5 mm lead flanged ball screw. A model containing "2005" from another manufacturer may provide the same basic diameter and lead, but this does not prove that the replacement nut will fit the original housing.

Before confirming the replacement, compare:

Screw diameter and lead
Nut body diameter and overall length
Flange diameter, thickness and mounting-hole pattern
Ball circuit configuration
Dynamic and static load ratings
Accuracy grade and lead deviation
Axial clearance or preload
Screw length, threaded length and usable stroke
Fixed-end and supported-end machining
Required support units and coupling dimensions

If the nut dimensions are different but the machine design allows modification, the replacement may still be technically possible. It should then be treated as an engineering replacement rather than a direct drop-in interchange.

Accuracy Code Differences

Accuracy codes require particular attention because the same letter-and-number format may not represent identical tolerances in every catalogue. The applicable standard, permitted travel deviation, useful travel length and inspection conditions should be checked.

DLY commonly supplies C7 rolled ball screws and C5 ground ball screws. The required grade should be selected according to actual positioning accuracy, repeatability, stroke and machine structure. A higher accuracy grade will not compensate for excessive axial clearance, flexible supports, thermal expansion or poor installation alignment.

Information for Model Matching

When the original model code cannot be fully identified, provide as much of the following information as possible:

Complete original model number and manufacturer
Clear photographs of the screw, nut and flange
Original catalogue page or dimensional drawing
Screw diameter, lead and total length
Nut and flange measurements
Shaft-end drawing or measured end dimensions
Required accuracy, clearance or preload
Axial load, speed, stroke and installation direction

A physical sample can also help identify an older or discontinued ball screw, but measurements should be combined with the machine's operating requirements. Copying dimensions alone may reproduce a component that no longer meets the required load, speed or accuracy.

FAQ

What does 2005 mean in a ball screw model?

In commonly used ball screw codes, 20 indicates a 20 mm nominal screw diameter and 05 indicates a 5 mm lead. The manufacturer's catalogue should still be checked to confirm its coding rules.

Are all SFU2005 ball screws interchangeable?

No. The diameter and lead may be the same, but nut length, flange holes, ball circuits, clearance, load rating and end machining can differ between manufacturers.

Can a DLY model directly replace a HIWIN ball screw?

Replacement may be possible after the dimensional drawing, load ratings, accuracy, clearance, preload and shaft ends have been verified. The series code alone is not sufficient to confirm direct interchangeability.

Is the ball screw nut code enough for quotation?

It may be enough for an initial check, but a complete quotation normally also requires the screw length, end machining, accuracy, clearance or preload and required quantity.

Conclusion

A ball screw model code summarizes important product information, but it is not a universal interchange standard. Numbers such as 1605, 2005 and 2510 usually help identify nominal diameter and lead, while series letters and suffixes remain manufacturer-specific.

When comparing DLY and HIWIN ball screws, first decode the basic specification and then verify the nut drawing, load rating, accuracy, preload, shaft length and end machining. Only after these items agree should the replacement be considered dimensionally and technically compatible.