The "U-NUT" brand trusted around the world.
"U-NUT" for peace of mind and safety, "FINE U-NUT" for bearings, and "TWIN FU-NUT" for precision lock nuts.
Loosening prevention nuts that support safety and security across various industries. With over 60 years since its inception, we offer a diverse lineup tailored to meet various needs.
"U-NUT" is a locking nut that is active in various industries, including motorcycles, four-wheel vehicles, industrial machinery, construction, and steel structures such as railways and bridges. "FINE U-NUT" is a locking nut for bearings that is used primarily in rotating shafts of machine tools and industrial machinery, such as ball screws and spindles. Additionally, "TWIN FU-NUT" is adopted in machine tools that require high thread accuracy as a precision lock nut and in cases where further measures against loosening are necessary. We offer a rich lineup including the locking nut "U-NUT" that ensures reliable fastening, the bearing locking nut "FINE U-NUT" that eliminates the need for traditional keyway machining and tooth washer installation for shafts, and the precision lock nut "TWIN FU-NUT" which further enhances the loosening prevention performance of FINE U-NUT with two friction rings. We can also manufacture special shapes in consultation with customers. *For more details, please refer to the PDF materials or feel free to contact us. *3D CAD data is also available for download.
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basic information
Exhibition Participation Information 【MEX Kanazawa 2026】 Dates: May 14 (Thursday) to May 16 (Saturday), 2026, 10:00 AM to 5:00 PM (until 4:00 PM on the last day) Venue: Ishikawa Prefectural Industrial Exhibition Hall (Halls 1, 3, and 4), 193 Minami Fukubata-cho, Kanazawa City, Ishikawa Prefecture, 920-0361 Booth Number: 4-048 【Metal Ring Anti-Loosening Function】 ■ Structure: The "U-NUT," "FINE U-NUT," and "TWIN FU-NUT" consist of the nut body and a friction ring (special spring), with the friction ring integrated into the top surface of the nut through a riveting process. ■ Function: The force generated by the elasticity of the friction ring, along with the force that pushes against the male thread flank surface, creates a pre-torque (friction torque) that acts to provide an anti-loosening effect.
Price information
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Delivery Time
※The delivery time may vary depending on the quantity, so please feel free to contact us.
Applications/Examples of results
【Delivery Examples (Excerpt)】 ＜U-NUT＞ ■ Motorcycle rear suspension and others ■ Bridge collapse prevention device ■ Marine engine ■ Railways ＜FINE U-NUT＞ ■ Machine tools ■ Semiconductor automatic sealing device ■ Ball screws ■ Food machinery ＜TWIN FU-NUT＞ ■ Automatic segiri processing machine ■ Sugarcane harvester *For more details, please refer to the PDF materials or feel free to contact us.
catalog（2）
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CAD data（64）
| Model number | overview | File |
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| FUN_SUS | sldpr data |
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| FUN_SS | sldpr data |
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| FUN_SC | sldpr data |
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| FUN_SUS | IGS data |
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| FUN_SS | IGS data |
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| FUN_SC | IGS data |
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| CU_SUS | sldprt data |
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| CU_SS_Molten Zinc Coating | IGS data |
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| U_SC | IGS data |
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| U_SC | sldprt data |
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| BLU_SUS | IGS data |
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| BLU_SUS | sldprt data |
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| GU_SS | IGS data |
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| GU_SS | sldprt data |
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| SU_SUS | IGS data |
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| SU_SUS | sldprt data |
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| TFU_SC | sldprt data |
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| TFU_SC | IGS data |
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| WU_SC | sldprt data |
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| WU_SC | IGS data |
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| WU_SS | sldprt data |
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| WU_SS | IGS data |
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| WU_SUS | sldprt data |
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| U_SS | IGS data |
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| U_SS | sldprt data |
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| U_SUS | IGS data |
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| U_SUS | sldprt data |
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| U_3 types_SC | sldprt data |
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| U_3 types_SC | IGS data |
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| U_3 types_SS | sldprt data |
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| U_3 types_SS | IGS data |
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| U_3 types_SUS | sldprt data |
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| U_3 types_SUS | IGS data |
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| FLANGE_SUS | IGS data |
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| UNC_SC | sldprt data |
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| UNC_SC | IGS data |
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| UNC_SS | sldprt data |
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| UNC_SS | IGS data |
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| WU_SUS | IGS data |
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| WELD_SS | sldprt data |
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| WELD_SS | IGS data |
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| CAP_SS | sldprt data |
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| CAP_SS | IGS data |
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| CAP_SUS | sldprt data |
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| CAP_SUS | IGS data |
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| FLANGE_SC | sldprt data |
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| FLANGE_SC | IGS data |
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| FLANGE_SUS | sldprt data |
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| Small U_SC | sldprt data |
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| Small U_SC | IGS data |
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| Small U_SS | sldprt data |
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| Small U_SS | IGS data |
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| Small U_SUS | sldprt data |
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| CU_SS_Molten Zinc Coating | sldprt data |
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| CU_SUS | IGS data |
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| FLANGE_SS | sldprt data |
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| FLANGE_SS | IGS data |
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| UNC_SUS | sldprt data |
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| UNC_SUS | IGS data |
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| Seat cushion with attachment_SS | sldprt data |
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| Seat cushion with payment_SS | IGS data |
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| Seat with metal base_SUS | sldprt data |
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| Seat with metal base_SUS | IGS data |
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| Small U_SUS | IGS data |
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News about this product（1）
Company information
Since our establishment in 1962, Fuji Precision has focused exclusively on the research and development of locking nuts, growing into a comprehensive manufacturer of locking nuts. The 'U-Nut' brand was the first in the industry to introduce the "metal ring locking function" to bolts and nuts, which were traditionally considered prone to loosening. This groundbreaking product received a significant response upon its release and has now grown to capture a 50% share of the domestic market, becoming synonymous with locking nuts. Although bolts and nuts may be considered small parts, they play a crucial role in connecting functions and technologies. They can be described as cross-point technology that combines cutting-edge technologies and opens up new technological fields. Fuji Precision regards this theme as an eternal proposition and has been committed to product development that anticipates the needs of the times, while pursuing high quality and high added value in our products. Our future goal is to become the world's number one comprehensive manufacturer of locking nuts. We will continue to strive to create products that meet your trust and contribute to the industrial sector and society.
