Loosening Prevention Nut-Fuji Double-Lock Nut

The Fuji Double-Lock Nut is a loosening prevention double-nut product that achieves its function thanks to the eccentricity of its top and bottom nuts.

This product was designed and developed in response to the demand for nuts that don't loosen spontaneously over time. It can be produced from any kind of steel and is available in a wide range of sizes from M10 to M100.

In official JQA vibration testing under identical conditions, compared with a standard nut that loosened in 13 seconds, the Fuji Double-Lock Nut achieved the surprising feat of remaining tight for 8 minutes and 23 seconds.

We also produce and sell the Fuji Triple-Lock Nut (patent pending), which has even better anti-loosening characteristics.

Nuts that are resistant to the effects of vibration and are not prone to spontaneous loosening are widely used for railways, bridges, heavy machinery, etc.

Hard metal nuts became a hot topic when they were first introduced in the media as a new product category in 1995.

Fuji Sesakusho's hard metal nuts have overcome one of the inconvenient aspects of conventional nuts be eliminating the need for several nuts to be used together for certain tasks because of their insufficient length.

The new nuts are mainly used in the installation of vibration damping devices in tall buildings, in the joints of iron reinforcing rods, and for assembly and installation of heavy machinery, etc. They carry out difficult tasks in invisible places splendidly.

Our technology for putting hard metal nuts through 500-long screws was born out of our skilled craftsmen's indefatigable product-making spirit.