Threadless Polyamide Nut Proves No Loose Link

Indian inventors Veena Agarwal and Rajendra Pal Agarwal have developed a polyamide-based bolt and nut combination in which the bolt is threaded, whereas the nut is threadless. The V Nut brings with it numerous advantages over traditional Nyloc (Nylon insert) lock nuts. Both nut types consist of a steel nut encircling a polyamide (PA) insert.

“According to David Fussell, president of VenturSource Consulting (Flagler Beach, FL), who has worldwide manufacturing and marketing for V Nut, “As no machined threads are made in the V Nut, it significantly reduces the cost of production and the production rate of the injection-molded nuts also increases.”

The V Nut’s polyamide insert is threadless, yet delivers much higher tightening torque. Image courtesy of VenturSource Consulting.

Further, a V Nut of a particular internal diameter can be used for all bolts of that size for fine as well as coarse threads. “This means that the usage of V Nuts will amount to great reduction in the inventory costs in comparison to conventional or Nyloc nuts.

Varying the height of the V Nut increases the tightening and loosening torque required. This property can be used to design nuts to cater to specific torque requirements. For a given size, in general if a plain steel nut requires a tightening torque of less than 1 Nm, the corresponding Nyloc nut requires about 4.5 Nm, while a V Nut of 8 mm height requires about 17 Nm. A V Nut with height of 12 mm requires about 25 Nm of tightening torque.

In conventional Nyloc nut and bolt arrangements, the length of the nut has no real effect on the torque. In this sense, the V Nut allows for potential weight reduction as the height can be configured to deliver the desired torque. This is especially important in the aerospace sector.

In addition, for V Nuts, the tightening and opening up torques required for fine threaded bolts are about 125% of the similar required values for the coarse threaded bolts.

Further, if the V Nut is tightened and untightened ten times, it still retains around 200% of the tightening torque requirement compared to that of a Nyloc nut tightened for the first time.

Mechanical fasteners play a vital role in daily life. They are used in a variety of applications, right from holding together a piece of furniture, to hi-tech automobiles. Mechanical fasteners are broadly divided into permanent and non-permanent fasteners. Threaded bolts and nuts are one such type of nonpermanent mechanical fasteners.

Generally plain nut and bolt assembly require minimal little torque to tighten. This also means that the plain nut will easily loosen with the application of external load or by small vibrations.

In conventional Nyloc nuts, a small washer made of a polyamide material is used within the threaded nut. These nuts require significantly more torque to tighten and accordingly more torque to loosen than a plain nut. The V Nut requires even more tightening torque, thereby further decreasing the likelihood of loosening.

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