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Three Reasons to Wear a Coat

It’s the middle of winter. A chill breeze blows the snow across a well-lit parking lot toward the Dart Machinery shop.  A man dressed in thick winter clothes plods his way across the snow toward one of the entry-ways.  In his right hand he holds a durable looking, professional grade aluminum snow shovel.  On his way across the lot he passes a snow drift of impressive size, but he does not give pause.  His shovel has never known the menial toil of moving snow, nor will it ever.  He has come to Dart because his shovel exists for the glory of the race-track… err… race-hill… wait, what!?  The man is a snow shovel racer, as he explains once he enters the shop (Yeah, we were confused too).  As it turns out snow shovel racing is an officially sanctioned activity, with organizers and sponsors and whatnot.  Who would’ve guessed?

After some bemused discussion about the exact nature of his sport with several Dart employees, he explains that he is looking for the coatings department and that he found his way here on the recommendation of some friends, who are members of a prominent funny car team.  They had the idea that the same Teflon blend coating that they use in their 300mph engines could really help his snow shovel racing career take off.  He doesn’t plan on going quite that fast, but he does plan to break 40mph, which seems pretty respectable for a shovel.  In the end, he and his low friction shovel (Now sporting a Dart sticker) had a great racing season, finishing first in his class.

You might be asking yourself at this point, how does any of this snow shovel nonsense pertain to performance vehicles that actually have engines?  The answer isn’t overly complicated.  Physics is physics: whether it’s a snow shovel or an engine, the forces at work are basically the same.  Every engine builder worth their salt knows that coatings can be used to great effect when trying to persuade the forces of physics to co-operate with your plan of making a big piece of metal go really fast by using explosions and lots of moving parts.  What’s not usually as well known is the incredible versatility that coatings have in dealing with a huge range of problems.

The number of uses for various coatings in performance applications is mind-boggling and nearly limitless, but in order to keep the possibilities cost effective and manageable it’s useful to think about it in terms of the three most common problems that coatings are used to address.

Coatings can be applied to a wide variety of components to enhance performance as well as longevity.

The big three we’re speaking of here are:

1. Friction

2. Heat

3. Corrosion

These three factors play a huge role in determining the power potential, efficiency and durability of an engine.  So when evaluating how you might solve a problem or create a benefit where one of these elements is involved, a coating may be worth consideration.  There are also cosmetic benefits, of course, because a lot of coatings can be made to look very cool, but for purposes of this article we’ll stick to performance uses.

Friction

Friction reducing coatings are commonly used on engine bearings, piston skirts and other similar applications to reduce wear.  Durability applications probably offer the most bang for your buck with these sort of coatings, often extending the lifespan of pistons or crankshafts well beyond what they would normally reach.  However, there are also a multitude of less common applications for these sorts of coatings that can be used to enhance performance.  Turbocharger units are sometimes coated internally in order to increase power output by reducing resistance to the flow of air, this is a particularly interesting application since people rarely consider the effect friction can have on airflow itself.  Another type of coating, applied to the piston wrist pins, allows for decreased friction in an area where an oil film is not present during normal engine operation.  Areas that are not oiled, but whose operations are affected by friction are prime targets for the flexibility of a coating.  Conversely, some anti-friction coatings make use of their properties in areas where retention of oil is actually undesirable, for example, a coating that sheds oil can be applied to crankshafts in order to reduce windage.  That is not to say that low friction coatings in areas that are oiled regularly should be limited to those areas that need to shed oil.  It has been shown that certain low friction coatings applied to key oil lubricated areas can actually lower oil temperature by a significant margin, allowing for the use of thinner oil.

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