In previous articles on the subject of crankshaft materials and hardening, we have made reference to the benefits of having residual compressive stress at the surface of the component. With the nitride hardening treatment used extensively on crankshafts, we not only make the crankshaft more wear resistant, but the change to the composition of the surface also imparts compressive residual stress. There are other methods of achieving this other than by nitriding the crankshaft, and we shall begin to look at these after examining a simple case to show the benefits of residual compressive stress. Read more…

We should all be very familiar with the primary functions of a crankshaft, namely as part of the mechanism which converts reciprocating motion into rotary motion, and to transmit torque to the outside world, where it might drive a gearbox, a generator or other piece of equipment. What a great many crankshaft designs also do is to provide lubrication channels which allow the passage of oil to the big end bearings, and possibly thereafter to the small end of the connecting rod.

Many years ago, crankshafts were designed with external oil gallery circuits made of thin metal tubes fastened Read more…

In the design of crankshafts we have to incorporate counterweighting for various reasons, either for reduction of bearing loads, or to reduce or eliminate primary couples.

Often this is achieved through careful design of the crankshaft and the counterweights are incorporated into the crankshaft. What we aim to do in providing a counterweight is to achieve a certain moment relative to the crankshaft axis. Depending on the configuration of the crankshaft these may or may not be directly opposite Read more…

In the previous article, we looked at the hardening and tempering of crankshafts. This month we shall look at the final and probably most important stage of heat-treatment, namely that of surface treatments, especially nitride hardening, more commonly known as ‘nitriding’. Nitriding is essentially a surface treatment, and its effect extends to a finite distance below the surface of the component.

Before we start, we should note that nitriding Read more…

In the previous article, we looked at the first stages of heat-treatment in the manufacture of crankshafts. Certainly in Formula One, the most popular heat treatment that will be mentioned will be nitriding. Nitriding, as most of you will know, is a surface treatment which, if specified correctly, should have no effect on the bulk of the material, often referred to as the core.

When we specify the material for the crankshaft, we need to be careful not only to specify the composition of the material, but also the level of mechanical properties Read more…

The article last month covered the subject of materials used for Formula One crankshafts. This feature looks at the subject of heat treatments currently used in Formula One.

As we saw last month, the materials in current Formula One use are mainly nitriding steels. By nitriding steels, we mean those with a composition containing elements which are strong nitride-formers, chief among these being chromium, aluminium, molybdenum and vanadium.

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As was mentioned in the previous RET Monitor article on crankshafts, it is our belief that nitriding steels are the most commonly, if not exclusively used materials. This month we take a closer look at nitriding steels for crankshaft manufacture, expand a little more on the importance of the ‘cleanliness’ of these types of steel and touch briefly on the benefits of nitriding.

The bar-stock used to make an Formula One crankshaft is not necessarily much different from that used

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The crankshaft is perhaps one of the most critical components in the modern Formula One engine; its design is full of compromises and its manufacture is complicated and time-consuming.The ongoing fight to reduce friction leads the designer to ever smaller bearings, but for each engine there is a point at which friction begins to increase again as crankshaft flexibility causes edge loading on bearings. There are a couple of options for bearings, namely the almost ubiquitous plain journal bearing, and the less common roller bearing. Both plain and roller main bearings have been used in Formula One in recent years, although some manufacturers did not find the expected gains with the roller bearing when they tested it. Read more…