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C. Tate
02-16-2004, 11:38 AM
Here is the story. OD grinding 303 SS annealed condition 1.375 dia 7.5 long. 60 grit silicon carbide wheel designation 39c60-jvk. 14x2x5 wheel running 1750 rpm. The work is 200 rpm (per Norton), plunge at .030 ipm and traverse at 25 ipm. To get the parts to come out it is necessary to rough, dress, finish, dress.We have .010 on OD to grind off so we rough OD to .0005 over and finsh with a traversing pass. Wheel wears so fast you have to dress after every operation even finish pass. Seems to me you could at least grind 2 or three parts per dress. What do you think?


Thanks
C. T.
(tolerance =+0.0000 /-0.0003 inches)

Alan in Oz
02-17-2004, 12:22 AM
I would have thought that a 60 grit wheel would be loading up rather than wearing so rapidly. From my book on cylindrical grinding for your type of wheel and material diameter the work speed rec is about 80 - 100 rpm. Would a 46 grit and slightly harder wheel be better considering your surface speed at about 6,500 fpm which is at the upper end, assuming surface finish is not too critical. Just thoughts.

Alan in Oz
02-17-2004, 05:13 AM
Have just found the bit in the book (1937) that I was looking for earlier, "Relatively fast work revolution with soft wheel causes the wheel to to wear rapidily".
There was person posting under the name of "Anonymous" some time ago on one of these boards that was very knowledgeable on grinding matters, maybe he can provide some ideas if he's around.

C. Tate
02-17-2004, 09:05 AM
I was running at 120 rpm to start and we could not even get the parts to finish without taper because the wheel was braking down so fast. Norton gave me the parameters as far as rpm and traverse rates. I tend to agree about the grain size. This wheel does load but not badly and next time I will go to a 46 grit wheel. What hardness do you think would be appropriate?

Thanks
C. Tate

Alan in Oz
02-17-2004, 09:59 AM
I would have thought an L or maybe M but on looking at my Norton list of avbl wheels here (Aust) I see these are not so common in your diameter, maybe your side is different. However going for a coarser grit it does not need to be as hard, K which I see listed maybe is OK in 46 grit.

C. Tate
02-18-2004, 12:33 PM
Thank you for the help. We will see what happens. I am going to go to the 46 grit wheel k hardness and try it again. Will post results.

CT

Betterhalf
02-18-2004, 03:35 PM
Received a recommendation back from PGW re this;

Pacific Grinding Wheel recommends 80C60-L8-VSK This should net out at about 1 1/2 grades harder but with a more open structure that should help keep it cutting. This should greatly reduce the need for dressing. Pacific grades in this material tend to act softer than Nortons, that's why the grade letter grade jump.

Koloya
12-17-2004, 08:43 PM
1

[This message has been edited by Koloya (edited 12-18-2004).]