Harder material sparking bigger?

John in CA · Jan 11, 2010

This is just a curiosity thing for me, it doesn't bear on the result of any particular job, but it seems like I can take a .0005" surface grinder cut on, say, A2 62-65 RC, and the cut will throw a pattern of sparks as big as if I had taken a cut twice as heavy in the same material, annealed. Could just be my imagination, but have any of you noticed this? If so, can anyone tell me why?

cash · Jan 13, 2010

For tool steel this is the case. We grind both annealed and hardened and see the exact thing. I guess I have never thought of the reason why this happens.

I would have to speculate that it has to do with the hardness of the material. Harder material you actually break the material away from the steel as you grind, thus the sparks from more heat and the material breaking away.

On annealed material the grinding wheel may do more pushing of the material so you do not get real defined sparks, plus not as much heat.

This is the best I can think of.

Jeffrey Badger, aka the grinding doc, who is featured in CTE magazine may have a more scientific explination if you would ask.

http://www.cuttingtoolengineering.com/sc_search_new.php?scPK=28

John in CA · Jan 13, 2010

Thanks Cash, that seems like a very reasonable hypothesis.

machine1medic · Jan 16, 2010

Take a brand new say Gerber knife and a peice of "Hickory",
see how much you can slice off in one pass.
Now a peice of "yellow pine", ....... Observe.

Each individual grain of the wheel, is subjected to much more
pushing force to peal away the 62 RC.
so the much greater friction, and consequently heat build-up.

What I would like to know, is .........
What is happening out at the end of a spark-trail, from grinding
some alloys, when the spark BURSTS.

m1m

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Harder material sparking bigger?

John in CA

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cash

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John in CA

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machine1medic

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