Ball Screw SFNU1605

Tianjin OuNaiDa Transmissions Technology Co., Ltd. is one of the leading manufacturers and suppliers of Ball Screw SFNU1605 in China. If you're going to buy high quality Ball Screw SFNU1605, welcome to get more information from our factory. Also, custom service is available.

Dust-Proof Ball Screws - SFNU Series for Contaminated Environments

Woodworking, stone cutting, plasma tables, foundry equipment, cement plant machinery. The axis works fine for a few months, then the running torque creeps up, the positioning gets inconsistent, and eventually the nut is scrap.

Open the nut and you find the cause: wood dust, stone slurry, or grinding swarf has worked its way into the ball circuit, mixed with the grease, and turned it into lapping compound.

The SFNU series is the standard SFU geometry with a sealing arrangement designed to keep that out. Same shaft diameters, same leads, same mounting dimensions in most sizes - so it drops into an existing design where a standard screw is failing prematurely.

SFNU Series Dimensions

Dimensions in mm. Larger sizes available on request. Left-hand thread available on selected models.

Comparing With the Standard SFU Equivalent

If you are considering a swap, the dimensional differences are small but not always zero. Two examples from the tables:

SFNU1204 vs SFU1204 - the nut outer diameter is 24 mm on both, but the SFU version is listed as 22/24 depending on variant, and the flange is 40 mm on the SFNU against 42 mm on the SFU. Nut length goes from 35 mm to 40 mm.

SFNU1605 vs SFU1605 - identical 28 mm nut and 48 mm flange, nut length 40 mm against 42/50 mm. Effectively interchangeable in most housings.

The point: check the nut length and flange diameter against your housing before assuming a direct substitution. The load ratings and ball diameters are the same, so the performance calculation does not change.

What the Sealing Actually Does

The sealing arrangement is a wiper at each end of the nut that scrapes contamination off the screw thread before it can enter the ball circuit. It works well against the particulate that kills screws in dusty environments - and it has two consequences worth planning for.

Drag torque is higher. The wipers contact the thread, so there is friction that a standard nut does not have. On small screws with low motor torque this is worth checking rather than assuming.

Seals are a wearing part. They are doing a mechanical job against abrasive material, and they will degrade. In a genuinely harsh environment, plan on inspecting them and treat them as consumable rather than permanent.

Sealing is not a substitute for a cover where one is practical. The best result in a stone-cutting or woodworking machine is usually a bellows or telescopic cover plus a sealed nut, not one instead of the other.

Where It Pays For Itself

• CNC routers and woodworking machinery - fine dust penetrates everything
• Stone and tile cutting - abrasive slurry
• Plasma and laser cutting tables - metal spatter and fine dust
• Foundry and casting equipment - sand
• Cement, ceramics, and mineral processing
• Textile machinery - lint accumulation
• Outdoor and semi-exposed installations

Where a standard SFU is the better buy: clean assembly rooms, enclosed machine tools with effective way covers, laboratory and medical equipment, and any application where the extra drag torque matters more than contamination resistance.

Lubrication

A sealed nut retains grease better than an open one, which is an advantage - but it also means contamination that does get inside stays inside. Relubrication intervals matter more here, not less. See our guidance on lubrication intervals and grease selection for the detail.

Support and Matching

SFNU screws use the same BK/BF, FK/FF and EK/EF support units as standard screws, with shaft ends machined to your drawing. In dusty environments the AK/AF sealed support unit types are worth considering alongside the sealed nut - the support bearings face the same contamination.

What to Send Us

1. Shaft diameter and lead, or the model you are replacing
2. Stroke and total shaft length
3. The contaminant - wood dust, stone slurry, metal swarf, sand
4. Whether a cover or bellows is fitted
5. Load, speed, and axis orientation
6. Existing housing dimensions if this is a retrofit
7. Quantity

If you are replacing a screw that failed early, tell us how long it lasted and what the failure looked like. That usually tells us more about the right specification than the original part number does.

Manufacturing

Tianjin OuNaiDa has produced precision transmission components since 2008 - 20 years of manufacturing and 15 years of export experience across 300+ overseas distributors, to CE and ISO 9001:2015 standards.

We supply the complete axis: ball screws, support units, couplings, and linear guideways, with matched shaft-end machining.

OEM and ODM accepted. Samples available. Technical support 24 hours.

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