I was wondering. Has anyone ever electropolished the metal-to-metal, lubricated surfaces in an engine, like the main, rod, and cam bearings, lifters, etc. and what were the results? I know it's been used on intakes and exhausts with good success, but I haven't heard of it being used on engine wear surfaces. Maybe since they have specified clearances and are lubricated, there's not much benefit?
Polishing wouldn't work on the cylinder ring seal because it uses oil and compression to seal. Rings and the cylinder wall need to seat or break in together and polishing would delay that. You can't polish the bearings because they're made up of soft metals and are better off with a dull surface to help oil adheasion anyway. The crank is often polished but I don't think the extra cost of micropolishing would be worth it except for racers. Valve stems come polished from the factory. The only benefit, if it were possible to polish every wear surface in the engine, would be at startup. Exept in extreme cases the wear at startup is minimal, though.
John opined in news: snipped-for-privacy@corp.supernews.com:
What would the benefit amount to, if there WAS one?
Engines already last far past the lifetime of the body if maintained... and most owners get lax in maintenace once the body starts to go anyway....
It wouldn't be noticeable to us street machine guys. :)
There's benefits to electropolishing in some applications. I'm just looking for some help in this particular application. Kind of like thinking out loud and seeing if someone helps you.
Electropolishing uses rectified current (DC) and a blend of chemicals in an electrolyte bath to remove flaws from the surface of a metal part. It's normally used after mechanical polishing has reached it's limit of the finest abrasives available (500 grit +) to yield the highest quality polish available. Since it uses chemicals and not mechanical abrasives, it's equivalent to sanding/polishing on a molecular level. There is no higher degree of polish available than electropolishing. It leaves a microscopically smooth surface that is highly reflective and has a bright surface. It improves seals, lowers friction, and improves heat and light reflection. It's the ultimate "mirror finish".
This is all in the direction of goodness when it comes to less defects in metal surfaces, lower friction, higher RPM, and more horsepower. I just don't know how much is gained when the dimensions of the surface imperfections get much, much smaller than the specified clearances between metal-to-metal wear points and it's bathed in an oil film anyway. You may reach the point of diminished returns and it's not worth the effort. Mark has indicated this is the case.
I forgot to add. Since electropolishing works by setting the metal part in a bath, it's great for areas that are difficult or impossible to reach with tools and fingers, like intakes and exhausts!
Agree here.
I'm not so sure about this. Oil adhesion would be good for startup. I know some oils have tackifiers added to improve this, but after startup when oil flow is established, it seems to me that the less defects in the two metal surfaces the lower the friction and less heat generation. The two metals need to be about the same hardness so the softer one doesn't get etched by the harder one, don't they? Less surface defects means less points for propagation of failures too. But I can also see that when the size of the defect gets very small relative to the clearance between the oil flooded parts, it may not be too beneficial.
Doesn't this kind of disagree with your previous statement? I can see both sides too, I just don't know where the break point is as a finer, and finer polish is obtained.
On Sat, 16 Oct 2004 02:39:55 -0400, John rearranged some electrons to form:
No. The bearing shells are soft. As you said, they are supported by a 0.001" (or so) film of oil.
John opined in news: snipped-for-privacy@corp.supernews.com:
So... you're saying you would use polish intake runners?
How about head intake passages? Hmmmm?
hehehe
Your first sentence isn't totally clear to me, and since the second sentence keys off the first, it isn't either. Hmmmm?
If you are asking, would I use electropolishing to polish intake runners and head intake passages. The answer is yes and no. I would use it to debur, but not polish. Like I said, it's great for those hard to reach places.
"Electropolishing" is a somewhat misleading name for the technology. A more descriptive name is "reverse plating". It actually removes metal, therefore the name "reverse plating". Imagine a metal surface. On a microscopic level it looks like peaks and valleys. If it's right out of the foundry, it'll be rough and the distance between it's peaks and valleys will be large. If it's just been mechanically polished to 2500 grit finish, it'll be smooth and the distance between it's peaks and valleys will be small. No matter the size of the peaks and valleys, electropolishing basically knocks the peaks off. It kind of mows off the top of the peaks first, then mows off a layer from the flat part that was just under the peak, and on and on and on. The longer you leave it in the bath, the more metal it removes.
So, if you start with a rough intake manifold and you leave it in the electropolishing bath a short while, it deburs it to a semi-rough surface that is good for creating turbulence, helping to further atomize fuel, and, hopefully, having a more homogeneous fuel/air mixture when it hits the cylinder.
And for exhaust ports, you'd mechanically polish those to about a 220 - 500 grit finish. Then throw it in the electropolishing bath for a long while. It'll come out with a mirror finish! Smooth as an oiled baby's butt to channel the exhaust out with the minimum of turbulence and backpressure.
Did this clarify the technology for you?
I forgot to add. Deburring an intake with those long tortueous paths (you know, the ones for low end torque) would be ideal for "reverse plating". Of course the ones with the straight, short paths right to the intake port (you know, the ones for high end horsepower) could be deburred this way too.
Have I answered your questions?
Ok John, Tell us the name of your business that does this, or are you just an investor?
Neither, I've used it before in my job, and I was thinking it may have some benefit in my chosen hobby. So, I started a dialog on it to see what happens. That's all, I swear.
I've used it for sanitation reasons, mainly to minimize adherance of stuff to metal. The surface defects get too small for things to grab on to, like pathogens, bacteria, viruses, glue-like substances (pressure sensitive adhesives, sealants, coatings), etc. They clean off much, much easier too.
However if anyone sees a way to get rich using it on our chosen hobby, please e-mail me.
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