In today’s world the possibilities for producing complex castings are much more sophisticated than ever. Whereas in the old days we only needed to worry about making patterns out of wood or steel/cast iron, now we can look at how to integrate as many functions as possible in as effective a solution as possible on a mass scale. So we no longer use only the traditional method of pattern making, but rapid prototyping techniques as well.
In general, an engine block casting consists of a number Read more…
An issue often not immediately considered when discussing an engine component such as a cylinder head or engine block, or any cast or forged part of them, is the way the machined features are positioned into the rough part. These features need to be positioned - or ‘targeted’ - correctly onto the casting, in order to get to a fully functioning component as the end product. So what are the important points during this initial machining, which will create the basis for all other machining features? It seems simple, but in reality this 
For ‘normal people’ stress is something to be avoided; not so however for engine developers. It is something we have learned to live with, and even use to our advantage. So, what about residual stress then?
Engine developers have always been regarded as ’strange’ people. The reason for this is unclear, although the fact that we tend not to come across as ’straightforward thinking’ people in the eyes of others may have something to do with it. But then finding non-straightforward solutions to problems is part of the engine developer’s job.
In response to my earlier articles on cylinder head cooling, two comments were posted on the website by readers. Both are written more or less from the perspective of current cylinder head material and its limitations, providing enough food for thought on alternative concepts. The major driver is to achieve sufficient cooling for the several components in the cylinder head, preferably in combination with a simple and lightweight design. 
In this article I want to emphasise the non-material side of the cylinder head, focussing on cooling. Whereas in previous articles I have provided some insight into cylinder head structure and coolant flow, this time I will look at cooling mechanisms in the cylinder head.
It’s an obvious thing to say, perhaps, but while an engine has to contain lots of moving components in order to function properly, it also contains many parts that are not intended to move at all. For example, cylinder heads and crankcases are not intended to move, but they are still in motion. In this article, ‘motion’ means that by introducing loads to the structure of these components, continuous deformation will take place, depending on the magnitude of that loading. 
In my past three articles on heads-blocks, I took a closer look at cylinder head loading. The main focus has been on the thermal loads of the cylinder head and which parameters of its design are of most influence in preventing it from cracking due to the thermal loading - so-called ‘thermo-mechanical fatigue’.
This is a follow-up to my earlier articles on cylinder head loading. Earlier, I described what is known as one of the most critical failure modes, Thermo Mechanical Fatigue, or TMF. In those articles the three main load cases were mentioned - assembly loads, (peak) firing pressure load and thermal load. For thermal load, further insight was given into the design of the cylinder head cooling jacket. The conclusion was that the jacket is mainly derived from the rest of the structural design, for example cylinder head bolt locations, inlet and exhaust ports and valve guides and seats. 
In my previous Heads-Blocks article I described the advantage of Compacted Graphite Iron (CGI) on one of the most severe cylinder head failure modes, Thermo Mechanical Fatigue (TMF). The main area of interest then concerned differences in material properties. Of course, material is not the only contributor to TMF robustness of cylinder head design, so in this article I will give an insight into another parameter influencing TMF, coolant jacket design. 
