Surface Grinding Inconel: Wheel Selection?
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    Default Surface Grinding Inconel: Wheel Selection?

    I've got a repeat job to surface grind some Inconel 718 parts, taking .005-.020" off each. We're grinding because there are hundreds of holes intersecting the surface at odd angles and minimizing burrs is very important. Surface finish and flatness aren't super important; .001" over a 6" square and 32uin or better are both fine.

    Currently we're grinding with the general wheel already on the grinder, white aluminum oxide 8" OD x 1" wide, I believe a 46I or O. The cut doesn't throw sparks and the wheel turns dark after a few passes. It doesn't seem to enjoy taking much more than .0015" off at a time with ~.1" WOC.

    Is there a more optimal wheel choice for inconel? I was thinking something more friable (softer) with a coarser grit, but have very little experience selecting grinding wheels.

    Thanks in advance.

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    I don't grind much Inconel, but I just use a general purpose pink wheel. Parts come out nice, but I do need to redress the wheel quite often.

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    You might be better with an abrasive belt type machine.

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    Thanks for the suggestions y'all. The general purpose worked while this was a prototype, but now that these are happening in quantity I was hoping to get a better fit wheel.

    Plastikdreams, that's an interesting idea, though these parts are pretty tall, 14". I'm not familiar with abrasive belt type machines, do they usually accept work of that size?

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    All depends on how much you are looking to spend really. We belt off a lot of castings, but like anything belts don't last long. Not knowing the size and shape kinda limits suggestions. A grinder may be your best bet, I don't know.

    Might want to look into a more open wheel, even contact Norton, I'm sure they can help.

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    I have ground 718 inconel.

    You will want a wheel of the softer side, so lets say like a 46 grit H or so.

    Run plenty of coolant.

    If you are running the parts before aging they sometimes like to move around. After Aging they are much nicer to grind.

    Not sure if long or short parts you are running. I have ground up to 72" long shear blades out of this stuff.

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    I think I have ground Inconel but cant remember a darn thing about it or what wheel was best. Seems like it ground like stellite, with black sparks, but that was a log time ago... I see around the net some advise CBN wheels but they are expensive and not that easy to quick dress. I would try to stick with AO wheels..perhaps a very open one..very wet..and Cash said H and he knows his stuff...
    Think you might call Radiac and ask their grinding guy..

    Think you would be best served with placing your diamond on a fixture/clamped to an angle plate or what so to be only half a wheel turn (or less) to dress, and dress often.

    I might double clamp my diamond .025 above part finish size so knowing that to take .025 or .0255 off from the fresh dressed wheel would make size to save the time to measure....perhaps you have an overhead dresser..good if you do.

    Are you down grinding to rough to +.003, then going cross increments for finish pass ..That can be a time saver...With a longer off at the ends if getting hot..down on the grind side only if still getting hot..
    Having a spotter on the chuck set to just under high size ..another time saver.. if having a green grinder hand have him put a tab of masking tape on the spotter for . .003 warning of getting close.
    You might center lap the holes for a fast de-burr at +.003.

    About 14 tall x 6" is a tall part so I would place a tall bump block-in on the go side touching near the top edge only so no chance of tipping the part worry. double clamped rod from an angle plate is good so you can squeegee the chuck ahead of the part for a fast next part..

    QT:[grinding because there are hundreds of holes intersecting the surface at.. and it is a bugger to mill.

    Very often the surface finish is/may be better than needed and so it doesn't hurt to have perhaps a 36 grit wheel in the shop just for back-up when you run into a tough job.
    Im not saying that wheel is what you need for this job..just good to have one.

    Q: How much time agerage just for this top grinding per part?
    Last edited by michiganbuck; 10-11-2019 at 08:43 AM.

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    Quote Originally Posted by michiganbuck View Post
    I think I have ground Inconel but cant remember a darn thing about it or what wheel was best. Seems like it ground like stellite, with black sparks, but that was a log time ago... I see around the net some advise CBN wheels but they are expensive and not that easy to quick dress. I would try to stick with AO wheels..perhaps a very open one..very wet..and Cash said H and he knows his stuff...
    Think you might call Radiac and ask their grinding guy..

    Think you would be best served with placing your diamond on a fixture/clamped to an angle plate or what so to be only half a wheel turn (or less) to dress, and dress often.

    I might double clamp my diamond .025 above part finish size so knowing that to take .025 or .0255 off from the fresh dressed wheel would make size to save the time to measure....perhaps you have an overhead dresser..good if you do.

    Are you down grinding to rough to +.003, then going cross increments for finish pass ..That can be a time saver...With a longer off at the ends if getting hot..down on the grind side only if still getting hot..
    Having a spotter on the chuck set to just under high size ..another time saver.. if having a green grinder hand have him put a tab of masking tape on the spotter for . .003 warning of getting close.
    You might center lap the holes for a fast de-burr at +.003.

    About 14 tall x 6" is a tall part so I would place a tall bump block-in on the go side touching near the top edge only so no chance of tipping the part worry. double clamped rod from an angle plate is good so you can squeegee the chuck ahead of the part for a fast next part..

    QT:[grinding because there are hundreds of holes intersecting the surface at.. and it is a bugger to mill.

    Very often the surface finish is/may be better than needed and so it doesn't hurt to have perhaps a 36 grit wheel in the shop just for back-up when you run into a tough job.
    Im not saying that wheel is what you need for this job..just good to have one.

    Q: How much time agerage just for this top grinding per part?
    Inconel in the aged state is only around 40 rc or so. I am thinking CBN would not be a good option? Unless it would be a special grade CBN designed for this rc range?

    Inconel is just one of those materials when surface grinding is tough. When we Blanchard grind it the best performance grinding is when we just pound the crap out of it, no dressing and the parts get hot as hell, but then they are moving/bowing on us. So we need to leave X amount of stock to then continually dress the segments to get everything flat again.

    Honestly, if the parts can be held in a vise, mill them.

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    Quote Originally Posted by cash View Post
    Inconel in the aged state is only around 40 rc or so. I am thinking CBN would not be a good option? Unless it would be a special grade CBN designed for this rc range?

    Inconel is just one of those materials when surface grinding is tough. When we Blanchard grind it the best performance grinding is when we just pound the crap out of it, no dressing and the parts get hot as hell, but then they are moving/bowing on us. So we need to leave X amount of stock to then continually dress the segments to get everything flat again.

    Honestly, if the parts can be held in a vise, mill them.
    To cut and finish from as fast we use a combination of abrasive saws, water jets, vmcs with carbide burrs, abrasive belting manual, semi automatic, and CNC, grit blasting, and hand finishing with abrasive belts and burrs. Nothing lasts more than a few parts, it's just the nature of the beast.

    I will say, wire edm leaves a very nice surface that's easily polished with a few stones.

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    Try one of the Norton TG wheels talked up by Norton in this cleverly disguised coolant test and let us know how it works.

    Critical Cooling for Gear Grinding Success | Norton Abrasives

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