Product Overview
A DFU ball screw is a flanged double nut ball screw: one main nut and one auxiliary nut, with preload set between the two. It is selected when a single-nut ball screw cannot deliver enough axial rigidity, backlash control or repeat positioning stability under medium or heavy loads.
DLY is a ball screw manufacturer with its own factory. We supply standard double nut ball screws from stock and build custom lengths and end machining to your drawing.
Technical Advantages
Structure. The two nuts are preloaded with a spacer (shim) between them, which reduces axial clearance in repeated linear motion. The flange gives machine builders a stable mounting surface. Rolling ball contact keeps friction and driving torque low.
Materials and heat treatment.
· Screw shaft: S55C, induction hardened.
· Nut: 20CrMo, carburized, hardness HRC 58–62.
· Steel balls: G10 grade, sourced from outside suppliers.
Quenching and tempering is the process our engineers regard as DLY's strongest.
Accuracy. Most DLY screws ship as cold-rolled C7 or C10, about 98% of shipments. Ground C5 is available on request. Accuracy follows GB/T 17587.
Engineer notes
· Machine tool and module applications must use preload.
· Hardness must be within the valid range.
Specifications
This table lists DFU ball screw specifications for common models. The DFU series diameter range is 12–80 mm (12 / 16 / 20 / 25 / 32 / 40 / 50 / 63 / 80), and the lead range is 5–50 mm (5 / 10 / 16 / 20 / 25 / 32 / 40 / 50). For other combinations, send your size and DLY will confirm availability.
Model | Nominal Diameter | Lead |
DFU1605 | 16 mm | 5 mm |
DFU1610 | 16 mm | 10 mm |
DFU2005 | 20 mm | 5 mm |
DFU2010 | 20 mm | 10 mm |
DFU2505 | 25 mm | 5 mm |
DFU2510 | 25 mm | 10 mm |
DFU3205 | 32 mm | 5 mm |
DFU3210 | 32 mm | 10 mm |
Model code, using DFU1605 as the example
· DFU: double nut, flanged
· 16: nominal screw diameter, 16 mm
· 05: lead, 5 mm
A suffix such as -3/2 or -4/2 gives turns × circuits. For example, -3/2 means 3 turns across 2 circuits.
Selection and Replacement Guide
Selection steps
1. Define the machine type, stroke length, load, speed and positioning or accuracy requirement. DLY engineers can confirm the choice from a model number, drawing, sample photo or these application details.
2. Choose the diameter and lead. A wrong lead is one of the most common selection errors.
3. Choose the support arrangement: fixed–fixed, fixed–supported or fixed–free. A wrong support method is the other common error.
Decide between single nut and double nut:
| SFU (single nut) | DFU (double nut) | |
| Rigidity | Standard | Higher |
| Backlash control | Basic | Better |
| Load | General applications | Medium and heavy loads |
| Preload adjustment | Limited | Better suited to preload control |
| Unit cost | Lower | Higher |
| Typical use | General CNC and light-duty machines | Higher-rigidity linear motion systems |
Replacing an existing screw. Check three items against the old part: outer diameter, length and mounting hole position. Send the old model number, drawing, the old part or photos of it, and the equipment type and working condition.
Custom and OEM
Standard customization. Custom length and end machining, typically 5–15 days depending on quantity.
- Support ends: BK/BF, FK/FF, EK/EF.
- Machining: keyway, flat milling, internal thread, hex end, step shaft, thread, bearing seat and retaining ring groove.
- Stainless steel screws can be made to order.
Non-standard. Non-standard lead or non-standard nut: MOQ 100 pcs, 20–30 days, cost quoted from your drawing.
OEM. Laser-engraved logo, custom packaging, color and label.
Information needed. A 2D or 3D drawing, or model plus length plus end form, or the old part as a sample or with its dimensions.
Applications
DFU for high-precision positioning. Positioning axes on CNC machines where a single nut does not give enough stiffness. Choose the model from the table above by load, stroke length and positioning requirement.
DFU for heavy-load transmission. Automated production lines, handling robots, packaging machinery and printing machinery running medium or heavy loads. Choose the model by the same three inputs.
Why DLY
Fast supply. Standard products are in stock, typically 7–30 days depending on order quantity, with MOQ 1 piece and free samples.
Direct replacement. Installation dimensions match the original model, and DLY helps confirm fit before you order.
Long specifications and customization. Screws up to 9 m long and 80 mm in diameter, backed by physical custom cases.
Verifiable quality. Every shipment is backed by first-article and patrol inspection and an outgoing inspection report that includes a dimension table.
· Inspection items: lead error, stroke variation, thread OD and raceway, runout and coaxiality, straightness, hardness, preload and idle torque, axial clearance, appearance and dimensions.
· Instruments: lead measuring instruments, CMM, hardness testers, profile projectors, contour and vision measuring systems, metallographic microscope.
· Test bench reports for life, noise and temperature rise.
· ISO 9001 certified.
Products Description
Zhejiang DLY Automation Manufacturing Co., Ltd. is a manufacturer, not a trading company. It was founded in 2005 with registered capital of RMB 50 million, and has 20+ years of manufacturing experience. It holds import and export rights and has exported since 2012. It is a National High-Tech Enterprise.
· Address: No.12, Baixian Road, Shuige Industrial Zone, Lishui, Zhejiang, China
· Plant: 30,000㎡+
Team: 200+ employees: 20 R&D, 25 quality inspection, 10 sales and export, 130 production
· Monthly capacity: ball screws 40,000 m, nuts 40,000 pcs; linear guides 60,000 m, blocks 40,000 pcs; linear shafts 20,000 m
· Equipment: cold rolling machines, CNC thread grinding centers, turn-mill machining centers, heat treatment equipment
· Management systems: ERP since 2011 and MES since 2020
· Patents: 60+, including 14 invention patents, among them a precision double nut ball screw assembly
· In-house processes: most key processes are done in-house: cutting, straightening, rough turning and turn-mill machining, screw heat treatment, cold rolling, thread grinding, OD and shaft-end grinding, nut raceway and internal thread grinding, ball selection and assembly, preload adjustment, cleaning, greasing and rust protection, inspection and packing. Nut heat treatment and surface treatment are outsourced, and some parts, including the steel balls, are purchased.
· ISO 9001:2015: certified since 2009. The current certificate is valid to 2027-09-25 and issued by Beijing Zhongjing Kehuan Quality Certification Co., Ltd. The scope covers ball screw assemblies, rolling linear guide assemblies and cylindrical linear guides, including production and related services.
Packaging, Logistics and After-Sales
Packaging. Units leave the factory greased and rust-protected. Screw ends are protected with sleeves, the surface is wrapped and the nut is fixed in place. Long or heavy screws ship in wooden cases with internal supports, 6250 × 300 × 300 mm; shorter items go in cartons. Each unit carries a batch number, laser marking and a packing label for traceability.
Shipping. FOB Ningbo or Shanghai. Sea LCL is the common choice; air and express are also available.
Payment. T/T, 30% deposit and 70% before shipment, in USD or RMB.
Warranty. 12 months.
After-sales. Keep the product, packaging and labels, and send photos or videos, the order number and a description of the problem. DLY engineers help assess whether selection, installation alignment, lubrication, overload or contamination is the cause, and continue to support model confirmation afterwards.
DFU Ball Screw FAQ
Q: Can a DFU ball screw replace my existing ball screw?
A: Compare the three items and send the details listed under Selection and Replacement Guide. DLY confirms before you order.
Q: Should I choose C7 or C5?
A: C7 is used for power transmission and C5 for positioning. C5 is ground and supplied on request, so state your positioning requirement when you inquire.
Q: How should I install and lubricate a DFU ball screw?
A: Do not strike the screw or nut with a hammer, because impact can damage the raceway or the preload. Check mounting surface accuracy, screw and guide alignment, coupling coaxiality, bearing support installation and nut mounting direction. Keep the screw lubricated in use, and clean and re-lubricate it if it is exposed to dust or metal powder.
Q: How should long screws be stored and transported?
A: Support them on wooden boards and ship them in wooden cases to reduce bending, collision and surface damage.
Q: How do I get an inspection report or certificates?
A: An inspection certificate can be packed with the shipment. Product photos, packing photos or a short inspection video are available on request, as are material grade and material certificates. For further certificate details during supplier qualification, contact DLY.
Q: What do I need to provide for a custom order?
A: Model, diameter, lead, length, end machining drawing and quantity. See the Custom and OEM section for the accepted forms of information.
Request A Quote
Send the model or drawing, DLY confirms key specifications and custom details, then quotes price and lead time, followed by production, inspection, packing and shipping.
Send Inquiry
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