The subject of the plating of fasteners is one that causes some debate. Many companies refuse to contemplate the use of plated fasteners, while some manufacturers will supply them only at a customer’s insistence and with a waiver that absolves them of any responsibility for losses resulting from a breakage.

Other companies are much happier to supply plated fasteners, however, having taken every precaution to minimise the chances of embrittlement before, during and Read more…

When we look at a bespoke fastener for a race engine, it is often clear that a great deal of thought has gone into its design, and considerable effort into its manufacture. Fasteners for use in race engines typically see much higher stresses than a typical production engine fastener, and they also tend to accumulate stress cycles at a much faster rate than in most other applications. We should not therefore be surprised that a lot of attention is paid to fastener design, especially with Read more…

There is a fondness for using socket-head screws in race engines. They are neat, and one can use a number of them close together, allowing the use of high clamping forces. Taking the example of adjacent 6 mm metric screws, two socket-head types can comfortably be placed 10.5 mm apart, whereas two hexagon-head versions need 11.54 mm, plus tool clearance to allow for a socket or a wrench, between screw centres. Read more…

In the previous article, the subject matter was the work done in the former USSR on fastener fatigue and particularly the positive effect that nut design and material selection can have on the fatigue life of studs and other male fasteners. In this article we will look at attempts by fastener manufacturing companies to achieve the same effects using relatively subtle changes in the fastener geometry. Read more…

Nuts are often given little consideration in design, especially compared to the stud onto which they engage. The reason is quite simple: nuts rarely fail unless they are completely unsuitable for the job. What is less commonly understood though is the fact that the nut design can have a critical effect on the fatigue resistance of the stud onto which it fits and the pre-load in which it is responsible for, in cases where stud failure coincides with the first loaded threads in the nut. Read more…

There have been a number of articles about fasteners that have mentioned friction, and as we have discussed, this has an important effect on the relationship between tightening torque and tension. Although torque-based tensioning of fasteners is not ideal, having a large number of unpredictable variables, we often don’t have much choice other than to use this method.

The torque-tension relationship relies on a number of Read more…

When we talk about friction in regard to race engines, we are normally referring to the power or energy lost due to it, but the phenomenon of friction plays an important role in the function of many components in a race engine. Fasteners are a particular example.

For critical applications, we would ideally like to measure the tension in a fastener directly, but this is rarely possible. Our next best method of gauging the tension in a fastener immediately after tightening is to measure its Read more…

When we look at bespoke engine studs, which are generally designed in such a way that engineering is given far more thought than cost, many of them will have a larger diameter and coarser thread at the ‘metal end’ - the end installed in the casting. Studs for mass production very often carry the same thread at both ends, or have a continuous thread over the whole length of the fastener.

Have you ever wondered why this is so? It is quite often Read more…

In the previous article on fasteners, we looked at a very clever design of threaded fastener that used a composite shank with the threaded portions of the component still produced in high-strength metallic materials. Not only do these fasteners use a polymer-matrix composite shank but, being made of multiple parts, they are, in the broader sense of the definition, a composite component.

A European company has developed a new form of composite fastener that is a pure polymer-matrix Read more…

In a recent article, the subject of using fasteners for composite components was discussed. The number of components for which composites are considered is increasing considerably, and in some race series their use is limited by regulations.

There are many areas in a Formula One engine, for example, where composites are expressly forbidden, but in production-based series, people are free to use composite components much more freely and so they Read more…