Making cast iron piston rings

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josodl1953

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I wonder if anyone could tell me more about the kind of cast iron that is generally used. There is grey cast iron with graphite in flakes and nodular cast iron , also known as Meehanite, with spherical graphite. Now it seems to me that one should use material with the highest possible yield strength. I used GGG 60 nodular cast iron for my Edwards, I do not know the U.S. equivalent but this was the strongest CI I could purchase. The Edwards drawings specify machining the rings in a cold pre- stressed condition, without heat treating. I had to make quite a lot of rings to get the required amount so maybe I should adopt the heat method but the question remains: does the tensile/yield strength matter?

zuigerveer orig.jpg


Jos
 

WOB

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According to this site, it seems nodular iron would be the obvious choice : Difference of gray cast iron and ductile cast iron
Tensile strength is important when spreading the ring over the piston crown before it drops into the groove. If a ring survives that, I don't think it matters what it is made of in our little engines. I think your will find that heat treating will improve your production yield.
 

peter smith

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1 have just finished the Kinner 5 cylinder radial the pistons are just over 1" dia there are 3 rings on each piston, I used the turn to size part off then break them in the vice with a piece of tool steel, gap them then heat them to cherry red while holding them open to give them tension. I fitted all 15 with this method using fine grain cast iron without any breakages.
 

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