Fuji Bearing Lock Nuts

Designed to locate, secure, and pre‑load bearings and shaft components with precision, our Fuji bearing lock nuts and bearing locknuts simplify assembly and reduce total cost of ownership.

Quality, Secure Bearing Locking Nut Solutions

Fuji bearing lock nuts are engineered for high-performance shaft fastening – eliminating the need for machined keyways, tab washers, or multiple components. The one-piece Fuji locknut features a spring‑peened friction ring that applies prevailing torque (via force P and reaction P’) to lock bearings—or gears and pulleys, securely on the shaft.

Available in carbon, high‑carbon, and stainless steel, Fuji lock nuts are stocked in sizes M10 to M150 (IEC holds inventory M10‑M100) with socket tools up to M50 readily available.

See the full Fuji Locknuts Catalogue!

Download our free technical documents and brochures.

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Markets

IEC have a range of mechanical solutions to suit a broad spectrum of markets and applications, from aerospace to skateboards.

Markets

IEC have a range of mechanical solutions to suit a broad spectrum of markets and applications, from aerospace to skateboards.

Markets

From aerospace components to skateboard bearings, IEC delivers precision mechanical solutions for an exceptionally broad range of markets and applications.

Case Studies

We act as partners, making our customers’ engineering challenges ours to solve, removing stress and freeing up time to turn ideas in to innovation.

Product:

Bearings

Application:

Peristaltic pump

Challenge:

Peristaltic pumps use occlusion rollers and positive displacement to feed fluid in industrial and medical applications, regulating flow and eliminating the need for valves. Bearings fitted in occlusion rollers have a cycle of coming on and off load with the potential to skip.

Solution:

It is important to select a bearing with high quality machining of its raceways to allow the bearing to readily accept these changes in state.

Product:

Bearings

Application:

Co-ordinate measuring machines (CMM)

Challenge:

5-axis measurement represents the biggest step-change in measurement capability ever introduced, delivering unprecedented speed and measurement flexibility, whilst avoiding the speed versus accuracy compromises inherent in conventional techniques.

Solution:

Duty of CMMs is generally low hence there is intermittent operation of bearings. Machines do require high reliability so products are tested and developed continuously, meaning technical support from bearing OEMs is critical. Some bearings are supplied with specific profiled outer ring designs.

Product:

Bearings

Application:

High pressure pure air generators

Challenge:

High pressure pure air generators are designed to replace rechargeable gas bottles on modern military aircraft. The system draws in atmospheric air to provide a continuous supply of high-pressure pure air, which results in unlimited mission duration and eliminates the logistics burden associated with gas bottles.

Solution:

For critical applications, reliability and resilience is paramount. IEC supplied components are capable of operating with high degrees of accuracy under extreme load.

Fuji Bearing Locknuts Catalogue

FUJI BEARING LOCKNUTS

The Fuji Fine-U-Nut was developed to simplify the assembly and reduce costs involved in securing ball bearings.

The manufacturer has more than 30 years experience in locknut technology and their factory is ISO 9001 approved.

Construction & Function

The Fuji Bearing Locknut is a one piece item where the locking function is performed by a spring peened into the top of the nut. In use the spring bears on the flank of the shaft thread with force (P) generating reaction force (P’) in the screw threads with a resulting high friction torque (prevailing torque). The nut therefore remains locked in position.

Introduction

Fuji Bearing Locknuts are manufactured in carbon, high carbon and stainless steel and are a stock item at IEC in sizes from M10 to M100.

KEY BENEFITS

Unique slim body design
Secure locking without keyway and tab washer
Improved shaft strength and balance
Simple infinite adjustment
Re-usable up to 100 times
Sizes from M10 to M150
Carbon, high carbon and stainless steel versions
Resists vibration and shock
Equally effective for rotation in either direction even with rapid reversals
One piece construction reduces stock and allows simpler, quicker assembly

PROOF LOAD & MAXIMUM TIGHTENING TORQUE

Part No		SS (Low Carbon Steel)		SC (High Carbon Steel)		SUS (Stainless Steel)
Part No	Prevailing Torque (Nm)	Proof Load (N)	Max Tightening Torque (Nm)	Proof Load (N)	Max Tightening Torque (Nm)	Proof Load (N)	Max Tightening Torque (Nm)
FU00	1.4	9500	13.3	12860	17.6	7710	8.9
FU01	2.2	11080	18.9	15000	24.8	9000	12.7
FU02	3.1	17810	36.7	24120	48.6	14470	24.3
FU03	3.7	20180	46.9	27330	62.2	16400	31.0
FU04	4.7	29020	77.8	39300	103.7	23580	50.9
FU05	9.8	41160	139.4	55740	185.3	33440	91.7
FU06	12.7	49400	199.4	66890	265.5	40130	130.6
FU07	16.2	66500	309.4	90050	413.3	54030	201.5
FU08	19.6	87080	458.4	117920	613.9	70750	296.9
FU09	23.5	109720	645.6	148580	865.9	89150	416.6
FU10	29.4	134580	877.2	182250	1177.5	109350	565.2
FU11	35.3	145140	1041.1	196540	1397.3	117920	670.8
FU12	41.2	158330	1238.1	214410	1662.1	128640	797.6
FU13	50.0	188680	1595.2	255500	2142.5	153300	1026.5
FU14	54.9	203190	1847.0	275160	2481.8	165090	1187.4
FU15	66.6	237500	2310.9	321620	3105.9	192970	1484.9
FU16	70.6	295560	3049.8	400230	4104.9	240140	1953.2
FU17	76.4	336460	3679.8	455620	4956.0	273370	2353.5
FU18	83.3	356250	4123.1	482430	5554.0	289450	2636.2
FU19	88.2	401110	4889.4	543180	6590.0	325900	3122.3
FU20	96.0	448610	5748.4	607500	7750.5	364500	3668.1

SOCKET TOOLS FOR BEARING LOCKNUTS

Sizes available up to M50.

Quotations/dimensions for larger sockets can be supplied on request.

Order Ref	Nut	D	L	h1	h2	s
FU00	M10x0.75	23	36	4.4	24	9.52 (3.8″)
FU01	M12x1.0	27	37	4.6	25
FU02	M15x1.0	31	38	5.7	26
FU03	M17x1.0	34	39	5.8	27
FU04	M20x1.0	38.5	40	6.9	28
FU05	M25x1.5	45.5	46.5	8.1	30.5	12.7 (1/2″)
FU06	M30x1.5	53	50	8.1	34
FU07	M35x1.5	60.5	53.5	9.2	37.5
FU08	M40x1.5	67	57	10.2	41
FU09	M45x1.5	74.5	60.5	11.2	44.5
FU10	M50x1.5	80	64	12.2	48

Socket tool material FU00 to FU06 – Japanese steel grade SCM435H FU07 to FU20 – Japanese steel grade SCM440H

AXIAL IMPACT VIBRATION TEST

Test Conditions Machine – NAS high speed screw loosening tester

Sample size	M20 x 1.0
Frequency	21Hz
Excitation stroke	11mm
Impact stroke	10mm
Vibrating acceleration of excitation table	10G
Test time	60 minutes
Direction of impact	Bolt axis direction
Clamping torque	53.9N.m (550kgf.cm)

Test Results

Sample Nut

Excitation Time (Minutes) 10 20 30 40 50 60

Test Results

Standard bearing nut with tongued washer

Looseness

Δ – x damaged washer (11 minutes) 20^o

Nut came off

FUJI Locknut

No effect

Fuji Locknuts Rotational Life Test

Test Conditions

Sample size		M55 x 2.0
Speed of revolution		2,300rpm
Testing cycles		One cycle (forward rotation, stop, reverse rotation, stop): 10 seconds
Stopping time		One forward rotation: 0.30 seconds. For reverse rotation: 0.27 seconds

Internal force applied to the nut during stopping
Sample Nut	Inertial Force : N.m (kgf.cm)
Sample Nut	For forward rotation	For reverse rotation
Standard Bearing Nut	0.14 (1.42)	0.15 (1.57)
FUJI Locknut	0.15 (1.52)	0.17 (1.69)

RESULTS
Sample Nut	Sample No	Result on endurance text
Standard Bearing Nut & Washer	1	Washer damaged & nut came off at approx. 110,000 cycles
	2	Washer damaged & nut came off at approx. 330,000 cycles
FUJI Locknut	3	No change after 500,000 cycles
	4

An interesting point to note is the difference in failure times between the two lock washers caused by inconsistent assembly. This is avoided by using the FUJI Locknut.

External view of testing machine

External view of damaged & detached washers (sample No 2)

BEARING LOCKNUT DIMENSION TABLE

SC Series	SS Series	SUS Series	Designation of Thread D1	D3		D4		g		T	S		h	H		Perpend-icularity of Bearing Surface
FU00SC	FU00SS	FU00SUS	M10x0.75	18	0-0.5	13.5	0-0.5	14.4	0-0.5	1.8	3	+0.2	4	5.2	+0.3	0.05
FU01SC	FU01SS	FU01SUS	M12x1.0	22		17		18.4		1.8	3		4	5.4	+0.3
FU02SC	FU02SS	FU02SUS	M15x1.0	25		21		21.4		1.8	4		5	6.5	+0.5
FU03SC	FU03SS	FU03SUS	M17x1.0	28		24		24.2		1.9	4		5	6.4
FU04SC	FU04SS	FU04SUS	M20x1.0	32		26		28.4		1.8	4		6	7.7
FU05SC	FU05SS	FU05SUS	M25x1.5	38		32		34		2.0	5		7	9.1
FU06SC	FU06SS	FU06SUS	M30x1.5	45		38		41		2.0	5		7	9.1	+0.8
FU07SC	FU07SS	FU07SUS	M35x1.5	52		44		48		2.0	5		8	10.2
FU08SC	FO08SS	FU08SUS	M40x1.5	58		50		53		2.5	6		9	11.2
FU09SC	FU09SS	FU09SUS	M45x1.5	65		56		60		2.5	6		10	12.5	+1.0
FU10SC	FU10SS	FU10SUS	M50x1.5	70		61		65		2.5	6		11	13.5
FU11SC	FU11SS	FU11SUS	M55x2.0	75		67		69		3.0	7		11	13.5		0.07
FU12SC	FU12SS	FU12SUS	M60X2.0	80		73		74		3.0	7		11	13.5
FU13SC	FU13SS	FU13SUS	M65x2.0	85		79		79		3.0	7		12	15.0	+1.5
FU14SC	FU14SS	FU14SUS	M70x2.0	92		85		85		3.5	8		12	15.0
FU15SC	FU15SS	FU15SUS	M75x2.0	98		90		91		3.5	8		13	15.8
FU16SC	FU16SS	FU16SUS	M80x2.0	105		95		98		3.5	8		15	18.6
FU17SC	FU17SS	FU17SUS	M85x2.0	110		102	0-0.75	103		3.5	8	+0.3	16	19.2
FU18SC	FU18SS	FU18SUS	M90x2.0	120		108		112		4.0	10		16	20.3
FU19SC	FU19SS	FU19SUS	M95x2.0	125		113		117		4.0	10		17	21.3
FU20SC	FU20SS	FU20SUS	M100x2.0	130		120		122		4.0	10		18	22.3
FU21SC	–	–	M105x2.0	140		126		130		4.0	12		18	22.3
FU22SC	–	–	M110x2.0	145		133		135		5.0	12		19	23.3
FU23SC	–	–	M115x2.0	150		137		140		5.0	12		19	23.3
FU24SC	–	–	M120x2.0	155		138		145		5.0	12		20	24.3
FU25SC	–	–	M125x2.0	160		148		150		5.0	12		21	25.4		0.10
FU26SC	–	–	M130x2.0	165		149		155		5.0	12		21	25.4	+1.5
FU27SC	–	–	M135x2.0	175		160		163		6.0	14		22	26.6
FU28SC	–	–	M140x2.9	180		160		168		6.0	14		22	26.6
FU29SC	–	–	M145x2.0	190		171		178		6.0	14		24	28.6
FU30SC	–	–	M150x2.0	195		171		183		6.0	14		24	28.3

NUT THREAD ACCURACY * Dimensions may be subject to change without notice due to our policy of product improvements. ISO6H (JIS Class 2) Unit : mm

Fuji BEARING LOCKNUT MATERIALS

Friction ring – 301 stainless steel

Material	JIS	ISO	BS
SS Low Carbon Steel	SS400 (or equivalent)	1.0044	43B
SC High Carbon Steel	S45C (or equivalent)	1.0503/1.1191/1.1201	070M46/080M46/080A47
SUS Stainless Steel	SUS304 (or equivalent)	1.4301	304S31

NOTES ON USE

Fine-U-Nuts are used for fastening critical components. When using Fine-U-Nut, strict compliance with the following is required:

A lead in chamfer equivalent to one thread pitch is required. The screw thread should be to ISO 965. (Tolerance Class 6g)

Lubricate the shaft before assembly or removal of the nut. With shafts of low hardness use a high performance lubricant.

To maximise effectiveness ensure there are at least two full threads beyond the friction ring.

The squareness specified for the mating face is achieved with a tightening torque equivalent to x2 the prevailing torque – see our literature.

Do NOT use a high rotational speed impact wrench.

Do NOT use the nuts on shafts with keyways.

Do NOT screw in the nut from the friction ring side.

Stop using the nut when excessive deformation or other fault is found in the friction ring and the clamp.

For severe or unusual applications please ask for our advice on 01202 339559.

Get your bearings

Utilise our customised Bearing Selector tool here.

Fuji Bearing Lock Nuts

Quality, Secure Bearing Locking Nut Solutions

Download our free technical documents and brochures.

Markets

Markets

Markets

Case Studies

Product:

Application:

Challenge:

Solution:

Product:

Application:

Challenge:

Solution:

Product:

Application:

Challenge:

Solution:

Fuji Bearing Locknuts Catalogue

FUJI BEARING LOCKNUTS

KEY BENEFITS

PROOF LOAD & MAXIMUM TIGHTENING TORQUE

SOCKET TOOLS FOR BEARING LOCKNUTS

AXIAL IMPACT VIBRATION TEST

Fuji Locknuts Rotational Life Test

BEARING LOCKNUT DIMENSION TABLE

Fuji BEARING LOCKNUT MATERIALS

NOTES ON USE

Get your bearings

Utilise our customised Bearing Selector tool here.

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