Plating solid lubricants on highly stressed parts

[WindyParticipant @windy30762]

My high performance flash steam engine has a cam and curved follower that is being lifted 10,000 to 15,000 times per minute (two stroke).

Because of weight restrictions to fit a high-pressure pump to spray lubricant would be difficult.

The follower is Stellite tipped like the old Triumph cam followers and the cam an air hardening steel.

At the moment the follower tends to get scuffed after a run and have to slightly reprofile it with very fine wet and dry abrasive paper.

I have used moly and also graphite pastes on them but wonder if there any ways to bond it to the surface similar to the ceramic coatings on some full size pistons.

Or any other type of wear resisting coating that might be worth trying.

I have asked various oil companies in the past but their products have not cured the problem.

If the hairpin valve spring pressure or steam pressure goes up the problem gets worse if lower the rpm is limited and speed reduced.

As it is experimental I am open to any suggestions that might be of use and get me that extra few mph.

This Forum has been a Godsend for the knowledge it’s members have and the lighthearted comments at times.

Paul

[WindyParticipant @windy30762]

Cams and followers

[Michael GilliganParticipant @michaelgilligan61133]

Years ago, I used a Two Sroke Oil called Bardahl [or some such]

This was remarkably effective, and coated all the engine internals with a pale Brown layer.

… No idea what was in it, or if it is still available.

MichaelG.

[Keith LongParticipant @keithlong89920]

Hi Paul

Have you looked at "diamond like carbon" as a surface finish?

I suggest you try a google search with the above or it's abbreviation "dlc". It's usually a pretty high end process (with associated costs) but it is available as a service. Renishaw and Morgan Crucible were a couple of firms offering it I believe.

It does get used on engine components of cars used in motorsport and not just confined to the F1 guys.

The other possibility is to see if you can track down one of the universities that is doing research and development in this field. You might well find that your application appeals to them as a test bed and the costs would probably be much lower (how are your negotiating skills?).

Keith

[Ady1Participant @ady1]

What about an insert? A pad?

Made of carbide or suchlike, where the stellite is

 

Mass production people wouldn't do things like that, too expensive and fiddly

Your project however, is a one off job

edit:

You would have to grind it to shape, like a jeweller would with a stone

Then "run it in" after fitting

Carbide inserts already have a hole in them

Edited By Ady1 on 19/01/2013 12:52:07

[Clive FosterParticipant @clivefoster55965]

Oerlikon Balzers do a wide range of vacuum applied coatings for high stress situations. Website is **LINK** for the UK division. Helpful even for the one off customer but not cheap. Around £400 to get all the innards of my Norton Commander gearbox done. The Triumph based 5 speeder being somewhat overloaded by 90 odd rotary horses and even Castrol R was only able to keep things spinning for 90,000 or so miles before gear damage started to appear. Post coating the gear change is much, much easier so I figure the claims for reduced friction are very valid.

Clive

[WindyParticipant @windy30762]

Thank you all for such quick replies I can't see the wood for the trees.

The University is a very useful suggestion as two retired academics (mathematics) that I drink with have been very helpful in the past to a suck it and see person like me.

Clives as well plus the other ideas by members.

A lot of food for thought.

Paul

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hello Paul ,

(1) Change the cam / follower geometry so that less scuffing occurs .

(2) Use a rolling contact follower .

(3) Fit a ring oiler – weighs almost nothing .

(4) Use of Stellite and special steels may be counterproductive – Stellite is very hard but it is also very abrasive if not micro lapped .

(5) Its not a scientific rule in engineering but if if harder and harder components don't work try the opposite – say Aluminium Bronze for the followers on existing hard steel cams as a first try .

(6) Turcite would work but I don't know how you would get the work done .

Regards ,

Michael Williams .

[Hi Speed ScrapParticipant @hispeedscrap]

Hi windy, dont know where you are located, but you could try this company here .

They manufacture friction modified oils, some of which have very unusual characteristics

such as surface adhesion etc. ( I have no association with this company, other than I built

their blending plant years ago) Will PM you with a contact there.

With the speeds you are running at, lobe/follower contact pressures will be extremely high

at impact, without seeing the scuffing marks or the cam/follower profiles, it is difficult to pass

my opinion on your problem.

My only suggestion is to closely examine cam and follower with a good microscope to try

and establish what is happening, ie surface cracks, localised hot spots, or contamination,

causing the scuffing.

There are some very knowledgable members here who know a lot more about this subject

than me and may also offer suggestions

my 2c.

Dave

[Mark P.Participant @markp]

We used to use a dry film lube on the fan blade root on RB211 engines which had to be baked on,but for the life of me I can't remember what it was called.I doubt that you would be able to source ant for home use.Sorry I can't be any more help.

Mark P.

[Ian S CParticipant @iansc]

Don't know if its any use in your situation Paul, but Andy Ross in his book "Making Stirling Engines" found a solution for scuffed aluminium pistons. "The pistons were coated with a baked onTeflon resin paint called "Xylan". " Ian S C

[WindyParticipant @windy30762]

I have just found an article on the various uses of Molybdenum disulfide as a coating to reduce friction on gun barrels and bearings and mentions about being applied by burnishing.

Is there a way that I can burnish the Molybdenum disulfide on to my cam follower or cam?

It does mention about using an ultra high vacuum chamber. 

Or is it a specialised process behond a home workshop?

Paul

Edited By Windy on 13/02/2013 19:32:49

[I.M. OUTAHEREParticipant @i-m-outahere]

Hardchrome possibly ? not as hard as carbide but low co efficint of friction , i have plated rocker arms from bikes to repair them and had no probs but they dont spin a cam at 10,000 rpm plus !

[SpringbokParticipant @springbok]

Hi Paul
You could try the RR Tech colledge (Bristol) the apprentices are building a car to beat the world record. I am sure they maybe able to help you. If you wish to take it further I can try and get contact details. our BSMEE now retired chairman is heavily involved as he has a high precision engineering business.

Regards
Bob

[gerry maddenParticipant @gerrymadden53711]

Hi Paul,

The traditional anti-scuffing treatment for cams is to add a chemical called ZDDP to the oil with a concentration of about 1%. This compound is an extremely effective anti-scuffing additive so may help if your problem is really "scuffing" – which is now also called 'micropitting' – as opposed to just tearing itself to bits .

Some engine oils for the older car already contain some ZDDP. It has been removed from 'current' engine oils as its harmful to cats (not the furry type.) You can also buy it under in small bottles for home mixing – google 'ZDDPlus'.

Solid coatings are an absolute jungle.

Gerry.

[magpieParticipant @magpie]

Many years ago i was involved in "drag racing" where the top fuel (nitro) engines were putting out upwards of 2000 bhp, I did'nt know a single racer that would run without WYNN'S friction proofing in the oil. When building the engine we used to brush the stuff on to all moving parts, then add to the oil as well. The reps used to do a very impressive demo and if that did not convince you they would let you drain all the oil from their car then take you for a 50 mile run. But as with many things that has no doubt changed !

Cheers Derek.

[WindyParticipant @windy30762]

I use a EP oil in the steam engine with moly paste on the cam but its not perfect.

I found this article about oil additives.

At a recent trade show we were at an aftermarket oil additive company was there with a machine that demonstrated how their additive reduced friction. It was a motor with rotating solid steel disc secured to the motor shaft and a torque meter with a flat piece ofsteel mounted on the torque arm. They put every type of oil on the market, one by one,on the machine & pressed hard on the torque meter and at about 20-40 lb-ft torque the torque arm would stall the motor….that is until they cleaned it off and tried their(chlorinated) aftermarket oil additive on the bearing & ran the test. People were amazed as the meter peaked out at 140 lb-ft. torque and still didn't stall the motor. We knew what was happening but many unsuspecting consumers were impressed up and standing in line to buy the additive. The next day we showed up with some Head& Shoulders Shampoo disguised in an oil bottle & had the aftermarket oil additive people try it on their test machine. The operator was amazed as the motor just barely stalled at140 lb-ft. The operator says that's pretty good stuff, what is it? We said “Head &Shoulders Brand Shampoo. He was quite embarrassed to say the least. Head & Shoulders Brand Shampoo has high levels of high potency ZINC in it that attaches itself to ferrous metals. Coke soft drink can do the same thing. ZINC reduces friction and provides antiwear protection and is present in most motor oils at a much reduced level. Now, would you put Head & Shoulders Brand Shampoo in your engine?Additionally, the test machine was measuring Extreme Pressure. Motor oils do not have Extreme Pressure (EP) additives blended in like gear lubes do nor do they need extreme pressure additives. A gear lube would not stall the motor as easily because gear lubes have high levels of Extreme Pressure additives blended in. As a side note, I know of two auto-parts stores within a half-mile of each other. One is a well-known family owned high quality performance type store. The owners of this store use the products they sell and also design and build racing and performance cars and havea full machine shop. They will not sell any type or brand of aftermarket oil additive.

[Sub MandrelParticipant @submandrel]

Twenty years ago I used to swear by Slick 50.

Neil

[AndyfParticipant @andyf]

Posted by Stub Mandrel on 14/02/2013 21:29:43:

Twenty years ago I used to swear by Slick 50.

Neil

So did my Dad, until he went bald and didn't need it any more

Andy

[gerry maddenParticipant @gerrymadden53711]

ZDDP stands for zinc dithiophosphate. This is an 'active' EP additive. 'Moly' teflon and other solid material additives are not 'active' EPs and simply dont work in high Herztian pressure contacts. There is some truth in your article but also a few contentious points.

Gerry

[Michael MallesonParticipant @michaelmalleson22793]

Have you tried motor cycle chain oil, or chain saw chain oil ? They are both formulated to stick to the chain and resist being thrown off. Mike.

[gerry maddenParticipant @gerrymadden53711]

ooops in my sleep i forgot one of the 'D' s …..dialkyl. dithio…. Oh and i had a look at my Head and Shoulders this morning. It does have lots of chemicals in it, (quite worrying really!) but no phosphorus compounds that I could see. This is a vital part of the 'EP' effect.

Gerry

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