Description

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DLY high load ball screws are configured for machinery requiring greater axial load capacity, rigidity and service life than a small-diameter standard ball screw can provide. Available configurations include large-diameter SFU single-nut ball screws and DFI double-nut ball screws, with nominal diameters up to 100 mm and multiple ball-circuit options.

Rolled C7 ball screws are available for general industrial transmission, while ground C5 versions can be manufactured for applications requiring tighter lead accuracy. Screw length, end machining, preload, support units and installation dimensions can be supplied according to the equipment drawing.

High Load Ball Screw Configuration

A high load ball screw is selected by its actual dynamic load rating, static load rating, rigidity, screw diameter, lead and number of ball circuits. It is not a separate accuracy grade. Increasing the screw diameter, ball size or effective number of load-carrying circuits generally increases axial load capacity, but the final specification must still be checked against the working load, speed, stroke, mounting arrangement and required service life.

DLY provides both single-nut and double-nut solutions. Large-diameter SFU models are suitable when high load capacity and a relatively compact nut are required. DFI double-nut models provide a longer nut assembly and higher rigidity, making them suitable for applications requiring preload or reduced axial clearance.

Available High Load Ball Screw Series

Series	Nut Structure	Available Diameters	Typical Selection
SFU	Standard flanged single nut	12–100 mm	General heavy-duty transmission with a compact nut structure
DFI	Flanged double nut	16–80 mm	Higher rigidity, preload and reduced axial clearance

Other DLY ball screw series can also be evaluated when the application has special requirements for nut profile, installation space or lead.

Representative High Load Models

The following models show the load range available from DLY. Values are taken from the corresponding SFU and DFI specification tables.

Model	Diameter (mm)	Lead (mm)	Circuits	Dynamic Load Ca (kgf)	Static Load Coa (kgf)	Rigidity K (kgf/μm)
SFU3210-4	32	10	4	3,390	7,170	45
SFU4010-4	40	10	4	3,910	9,520	55
SFU5010-4	50	10	4	4,450	12,500	65
SFU6310-4	63	10	4	5,070	16,600	80
SFU8010-6	80	10	6	7,810	31,800	106
SFU10020-4	100	20	4	9,420	39,183	134
DFI4010-4	40	10	4	3,910	9,520	107
DFI5010-4	50	10	4	4,450	12,500	125
DFI6310-4	63	10	4	5,070	16,600	140
DFI8010-6	80	10	6	7,810	31,800	180

Ca and Coa are axial load ratings expressed in kgf. They are not recommended operating loads. Actual service life and safety margin must be calculated from the equipment's working conditions.

Product Features

High Axial Load Capacity

Large screw diameters, suitable ball sizes and multiple circulation circuits provide higher dynamic and static axial load ratings.

Single- and Double-Nut Options

SFU single nuts provide a compact solution, while DFI double nuts are available for higher rigidity and preload requirements.

C7 and C5 Accuracy

Rolled C7 is the standard option for industrial transmission. Ground C5 can be manufactured for more demanding positioning systems.

Custom End Machining

Bearing seats, threads, shoulders, keyways and coupling ends can be machined according to the approved drawing.

Supply Specifications

Available series	SFU single nut and DFI double nut
Nominal diameter	SFU: 12–100 mm; DFI: 16–80 mm
Common lead	4, 5, 6, 10 and 20 mm, depending on series and diameter
Accuracy	Rolled C7 standard; ground C5 optional
Screw shaft material	S55C
Nut material	20CrMo
Thread direction	Right-hand standard; left-hand available by customization
End machining	Machined according to drawing
Support units	BK/BF, FK/FF and EK/EF series
MOQ	1 piece for regular specifications; customized designs require technical confirmation

Applications

High load ball screws are commonly selected for CNC machine axes, industrial presses, injection-molding equipment, heavy linear modules, automated handling systems, cutting machinery and other equipment requiring efficient conversion of rotary motion into controlled axial movement.

For vertical axes or equipment carrying suspended loads, a brake, counterbalance or separate safety mechanism should be included in the machine design. A ball screw should not be used as the only load-holding safety component.

FAQ

Q: Should I choose an SFU or DFI ball screw for a high-load axis?

A: Choose SFU when a compact standard flanged nut is suitable. Choose DFI when the application requires a double-nut structure, greater rigidity, preload or reduced axial clearance.

Q: Does a larger ball screw always provide a longer service life?

A: A larger model normally provides higher load ratings, but service life also depends on actual axial load, speed, alignment, lubrication, contamination, mounting rigidity and operating cycle. Selection should be based on a load-life calculation.

Q: Can DLY supply a complete machined ball screw assembly?

A: Yes. DLY can provide the screw shaft, ball nut, end machining and matching BK/BF, FK/FF or EK/EF support units. Couplings can also be supplied when the motor shaft dimensions are confirmed.

Q: Can the high load ball screw be supplied in C5 accuracy?

A: Yes. Rolled C7 is the regular industrial option, while a ground C5 ball screw can be manufactured after the accuracy, length, preload and end-machining requirements are confirmed.