Rivnuts™, What are they and how are they used?
by Andre F. Du Plessis
The name Rivnut™ was originated by B.F.Goodrich and was sold to Rivnut Engineering who holds the trademark for that name. Today, Rivnuts™ are used all over the world for various purposes and are manufactured in various shapes and sizes. In Cape Town and vacinity they are sold by Rivco Products (CC) in Parow Industrial (Parow East) area. Rivnuts™ come in extremely handy in the construction of an aircraft control panel, as the use will allow instrument panels to be bolted/screwed to a back frame from the front. Another use would be on a metal aircraft to affix inspection covers. One can literally think of a nut that is “riveted” to a frame or backplate hence the name Rivnut.™ (See Photo 1a, Photo 1b, and Photo 1c for examples of an aircraft control panel frame with the Rivnuts™ installed.)
What does it look like?
The Rivnut™ is a one-piece internally threaded and counter bored tubular aluminium or steel rivet that can be pulled up or headed while working entirely from one side, forming a bulge or head on the blind side. This upset is large enough to resist being pulled through metal or plastic even, under conditions of eccentric load. (See Photo 2 for a drawing of the Rivnut™ being pulled.) It overcomes the difficulty of installing brackets, handles or other attachments to tubular pieces. They come in standard or countersunk manufacture. (See Photo 3 for the difference between the two.) Obviously, the standard unit has a bigger “head” and is stronger, but the disadvantage being that the plate or bracket bolted to the tubular piece does not lie flat against the surface, where as, with the countersunk Rivnut™ the fit is absolutely flat.
How are Rivnuts™ installed?
The Rivnut™ is threaded onto a pull-up stud of a hand-heading tool. (See Photo 4a, Photo 4b, Photo 4c, and Photo 5 for the hand tool and various mandrels) The Rivnut™ on the header tool mandrel is then inserted in the drilled hole of the object and crimped in a very similar way to a pop rivet. When the tool is operated the Mandrel stud retracts pulling the threaded portion of Rivnut™ shank toward blind side of work, forming a bulge around the unthreaded shank area. By doing this, the Rivnut™ is clinched securely in place. Unthreading the tool mandrel leaves the internal Rivnut™ threads intact, unharmed. Installed Rivnuts™ also serve as blind nut plates for simple screw attachments.
Tips for installation
Care must be taken that not too much force is exerted onto the tool and therefor the mandrel pull-up stud, as the threads of the Rivnut™ may be damaged or sheared. The hole in the object into which the Rivnut™ will be inserted must be of the exact diameter and not too big. Do not debur the hole after drilling. The rough edges will help to secure the Rivnut™ and prevent it from “working its way loose”, as it will create an interference fit between the two surfaces. Countersink the hole for the countersunk Rivnut™, but take care not to sink too deep as it will weaken the installation.
Happy “Rivnuting”!!!!
Joe Butvin gave us this info: Just an update. The Rivnut Engineered Products company was sold to Bollhoff and International Fastening and Assembly technology company in August 2000. Bollhoff now owns the Rivnut Trademark and operates the Bollhoff Rivnut division in Kendallville IN. USA. FYI, Joe.
