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Annealing auto plug washers?

S

Steve Sampson

Well Known Member
With conventional aircraft plugs it is normal to anneal the washers before reinstalling.

With my P-mags I have auto plugs. What is normal procedure with these? They don't look as though they are made of copper. I don't plan to reuse them many times, but a 35 hour check appears to be appropriate.

thanks
 
If you can get new ones, that works, if not, I think Aircraft spruce sells 14mm copper gaskets.
 
Copper...

That brings up a good point, would there be an upside or downside to going to a 14mm copper washer here? The one the comes on an auto plug is normally crushed on the first install...I think you could re-use it, if you retorque it, but would it just be better to replace these with copper??
 
Heat the copper plug washer till its red hot and then let it cool naturally. This will soften the copper and allow a proper seat/ seal when refitting plugs. I also use a bit of thread lube when reinstalling.
 
annealing

My IA aways anneals the copper spark plug washers by heating red hot with a torch and then dropping them in cold water. I have aways followed this practice on my C182's plugs.

On my RV7a, I have dual PMAGs and use the recommended auto spark plugs. When I take them out, I replace them with new plugs. The last set I ran 135 hours on before replacing. I will probably replace them every 100 hours in the future. After all, they are only $2 per plug times 8 plugs is $16 total.

Just my opinion.
 
To anneal washers they should be heated and allowed to cool slowly. Quenching them in cold water will make them brittle, not soft.
 
Mel is correct....

...natural cooling keeps them soft, quenching makes them hard. Google it and you'll see what my A&P explained, as did Mel. Nothing wrong with reusing good washers but then some folks feel differently about economy and confuse it with unsafe practices. Not alway the case. Why waste when tried and true methods give economical results? Little things add up, but then maybe your portfolio is still looking terrific.....! :rolleyes:
 
Annealing Copper

Mel said:
To anneal washers they should be heated and allowed to cool slowly. Quenching them in cold water will make them brittle, not soft.
Click to expand...

Mel,
I have to ask you why quenching them in water is bad?. I learned this method (water quenching) 30 years ago from a Triumph motorcycle repair manual. It does not make them brittle in my experience. What is the disadvantage of water quenching?
I have found it advantageous to anneal all copper washers or head gaskets (motorcycles) prior to use. These parts get work hardened at the edges, during their manufacture.
Charlie Kuss
 
The purpose of annealing the washers is to soften them so that they will "crush" and seal. If you quench them in cold water the material will become more brittle and may not seal properly.
Take 2 pieces of steel. Heat them both. Allow one to cool slowly and quench the other one. Put them both in a vise and bend them. You will find that the annealed one, the one that cooled slowly, will bend much further than the quenched one before breaking.
 
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It doesn't matter

chaskuss said:
Mel,
I have to ask you why quenching them in water is bad?. I learned this method (water quenching) 30 years ago from a Triumph motorcycle repair manual. It does not make them brittle in my experience. What is the disadvantage of water quenching?
I have found it advantageous to anneal all copper washers or head gaskets (motorcycles) prior to use. These parts get work hardened at the edges, during their manufacture.
Charlie Kuss
Click to expand...

Actually it doesn't matter if you let them air cool or quench them in water.
They will still be soft. If you don't believe me..try it. I have.

You can test the "softness" by twisting them like you where trying to bend a penny.

I quench them in water because the scale boils off and they become nice and pretty. And you can install them sooner:D

Mark
 
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Maybe this topic needs another qualifier in that you may not "feel" the difference in the small copper washer, but it is basic metallurgy in that the structure of the material is very different given different cooling speeds. This is what annealing in this application is about. Creating a "loose" structure. You need to look at the material samples under a microscope to truly appreciate the effect of heat application, its rise rate, and cool rate on different metals. Most of them generally act the same and copper is not an exception. It is just a little more forgiving in process.
 
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Quenching Copper

Mel said:
The purpose of annealing the washers is to soften them so that they will "crush" and seal. If you quench them in cold water the material will become more brittle and may not seal properly.
Take 2 pieces of steel. Heat them both. Allow one to cool slowly and quench the other one. Put them both in a vise and bend them. You will find that the annealed one, the one that cooled slowly, will bend much further than the quenched one before breaking.
Click to expand...

Mel,
OK, I see the issue now. Copper does not have the same properties as steel or aluminum. For steel and aluminum, you are correct, you should not quench them. However, you can quench copper. It's actually the recommended procedure. You don't have to believe me. Try it for yourself.
Charlie Kuss
 
Quenching Copper

Mark Burns said:
Actually it doesn't matter if you let them air cool or quench them in water.
They will still be soft. If you don't believe me..try it. I have.

You can test the "softness" by by twisting them like you where trying to bend a penny.

I quench them in water because the scale boils off and they become nice and pretty. And you can install them sooner:D

Mark
Click to expand...

Mark,
Thanks for the explanation. I suspected that was the case, as obviously letting the washers cool in ambient air has worked for Mel. I'm not a metallurgy engineer, but generally, I find that the repair manuals will state the preferred method. I tried to Google this, but could not find an answer from a "definitive" expert.
I replied to Mel prior to reading your comments.
Can anyone direct me to a definitive answer? I'm not trying to start a "pissing contest". Now I'm simply curious as to what the engineers say.
Charlie Kuss
 
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Quenching copper in cold water certainly makes it softer than air cooling if you've worked this material extensively.

People can try it if they don't believe it as another poster said. Copper does not behave like most other metals in this regard.
 
The object is to soften the copper. So how about this? Test the methods: take 2 used gaskets, heat each to red hot, quench one and let the other cool slowly. Mark with a Sharpie so you can keep track of them. Put them in a vise against each other, offset rather than perfectly aligned, squeeze them down and see which one indents the other.
 
chaskuss said:
........... could not find an answer from a "definitive" expert.
I replied to Mel prior to reading your comments.
Can anyone direct me to a definitive answer? I'm not trying to start a "pissing contest". Now I'm simply curious as to what the engineers say.
Charlie Kuss
Click to expand...

Charlie, this info from the world of Bonsai(!) might help. Steve.

PS Not sure who is a definitive expert.

PPS This was great thrread drift away from the first question in post #1!
 
I been quenching

for 30 years and it always seemed to be softer than if i didn't have any water...or there wasn't a handy tree for cover..:)

Frank
 
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