What CNC Grinder to buy? 5000+ carbide parts/month

Targetcaller · Aug 12, 2020

Big company came to us with a P.O. for around 5000+ 6 inch diameter parts. They are carbide and need to be +/-.0001 flat and within dims. Looking to take off .004 a side. No "fancy grinding" (radius or forms) at all here just a large number of parts needing to be very flat and mirror finish. Willing to do whatever it takes to get the job done.

Have experience with CNC Edm/Mill/Lathe/ect. Very new to CNC Grinding. What are some grinders that you all would recommend for this type of a job? Good company? Good models?

Thanks,

-Targetcaller

Mike1974 · Aug 12, 2020

What exactly are you grinding on them? I see the flatness spec so I ass-u-me the faces? I think +/-.0001" flatness over a 6" diameter (again, assuming here) is going to be pretty damn tough. I would think you are into lapping territory there, but that's just a guess...

Maybe a double disc grinder, but no idea of tolerances they can hold?

DDoug · Aug 12, 2020

I have seen Blanchard grinders put in service for tighter than normal tolerances
(radio quartz crystals for one) and equipped with diamond wheels.

Could be a job for a lapper.

Where's Uncle Bob ?

Targetcaller · Aug 12, 2020

Grinding faces for thickness is all @Mike

CarbideBob · Aug 12, 2020

Stahli
DM-705 a nice and very fast machine but not sure it will do 6 inch.
Pricey and wait until you go to buy wheels for it. Pretty much king of the hill.

PR Hoffman double sided lappers. There are other makes.

6 inch at .0001 flat is certainly very hard to do on a Blanchard but possible. Head alignment and chuck cleanliness run to run critical. I would not try it but could see it being done
You would want two machines one setup to rough and the other setup to polish or a lapper for that.
Holding a six inch carbide round in on a Blanchard not easy as the parts like to spin in place.

Lappers are slow on carbide and this is one big part.
You say polished but no spec.
Blanchard with a 1000-1600 grit wheel will give a finish that measures just about zero but still has a look to it. Orbital machines as above leave a random finish which looks better to the eye.
Be aware of cosmetics. Have had this argument when the print calls out 3RMS or better.

This will not be cheap or easy.
Bob

1953chevB · Aug 12, 2020

need to look at a print, but flatness is usual done on faces, not diameters, diameters are usually cylindricity, light bands with an optical.
if it is just a round slug ,the faces don't need to be square a centerless grinder can do that. I have never machined centers on a carbide slugs
not my cub of tea for carbide parts.
maybe some one can chime on that, the other option be to grind between centers, but I don't know if it is practical to machine centers on carbide.
maybe edm centers if the customer allows it.
but the wheels require diamond , to grind carbide, look in to a supplier that can do that before you buy a machine
or better yet talk to a mfg of machine and try to grind some samples and see if it can cut the mustard.
edit define mirror finish , light bands or just look pretty , never done mirror finish on carbide just steel parts.

CarbideBob · Aug 12, 2020

Whoa,
1953 has shown that I maybe talking out of my ass.
Ass-u-med that it was top and bottom or 6 inch flat face.
OD? That makes me stupid.
Bob

newtonsapple · Aug 12, 2020

If it is just the flat faces of a round disc, there are shops that specialize in this work. The fact that there are shops that specialize in this should clue you into the nature of this work.

Sub it out to someone like this and see if you can make the numbers work A1 Lapping: home

1953chevB · Aug 12, 2020

CarbideBob said:
Whoa,
1953 has shown that I maybe talking out of my ass.
Ass-u-med that it was top and bottom or 6 inch flat face.
OD? That makes me stupid.
Bob

Hi Bob
not my intention at all sir the OP said this
Quote "Big company came to us with a P.O. for around 5000+ 6 inch diameter parts. "
that why it's not cool to not see a print.
my apologies if I offended you sir, your the carbide specialist.
I done a lot of aircraft parts in a grind shop, surface and OD ginding, rotary grinding holding .0001-.0002 tolerance, but
anything form 4-125 micro, a mirror finish means to look pretty, less than 4 micro, means can be super finish(2-4 micro ), or lapping.

-cg · Aug 12, 2020

Targetcaller said:
Big company came to us with a P.O. for around 5000+ 6 inch diameter parts. They are carbide and need to be +/-.0001 flat and within dims. Looking to take off .004 a side. No "fancy grinding" (radius or forms) at all here just a large number of parts needing to be very flat and mirror finish. Willing to do whatever it takes to get the job done.

Multi-station Disco, coarse and fine grind (and maybe polish depending on requirements) integrated in same machine. 6" is older so maybe easier to find used. Fixturing can be as simple as tape frame on vacuum chuck. Other brands would include Okamoto, what used to be Strasbaugh, etc.

There are vendors that have tweaked small Blanchard's to do this sort of thing (hard material grinding of round discs), but it is esoteric. Disco is probably a good place to start (they do the abrasives as well).

1953chevB · Aug 12, 2020

newtonsapple said:
If it is just the flat faces of a round disc, there are shops that specialize in this work. The fact that there are shops that specialize in this should clue you into the nature of this work.

Sub it out to someone like this and see if you can make the numbers work A1 Lapping: home

agreed the OP needs to describe better if its disk Carbide Bob is correct and I agree with him.

DDoug · Aug 12, 2020

So the big question is......What in the heck is the customer doing with
all these 6" round discs ?.... :crazy:

CarbideBob · Aug 12, 2020

1953chevB said:
....
not my intention at all sir the OP said this

It was a good point and I went with a gut that may have been wrong.
Please do not call me sir, it is Bob or Bobby. Sir or Mr xxx was my dad.
I am not a carbide specialist, just been doing it a long time. Plenty out there better than me.
Interesting note my dad's company was Carbide Engineering Specialists Inc. The guys from CESI (or sissy as the customers would like to poke).
I just try to help but I assure you that my shit does stink and I am often wrong.
Bob

Milland · Aug 12, 2020

digger doug said:
So the big question is......What in the heck is the customer doing with
all these 6" round discs ?....

Combat Air Hockey. You think regular hockey players lose teeth? You ain't seen nothing yet...

If it's the faces that both need to be mirror finish and flatness, it sure sounds like a lapping job to me, with at least two machines - a semi-finisher to clean the marks from grinding and get them near size, and a polisher.

I actually bought a couple of ~24" Spitfires that were used that way to grind optics for Air-Air missiles. I want to "CNC-ify" them, but so far they're just sitting there. Need to get my rump in gear...

1953chevB · Aug 12, 2020

CarbideBob said:
It was a good point and I went with a gut that may have been wrong.
Please do not call me sir, it is Bob or Bobby. Sir or Mr xxx was my dad.
I am not a carbide specialist, just been doing it a long time. Plenty out there better than me.
Interesting note my dad's company was Carbide Engineering Specialists Inc. The guys from CESI (or sissy as the customers would like to poke).
Bob

Thank you Bob and will do.
experience is a valuable, I appreciate you comments

Targetcaller · Aug 12, 2020

Thank you for everyone's insight. Its a very hard project and a large quantity. It will definitely be worth the R and D to get this done. I can not show print or specs NDA sort of thing. I will continue to watch this post as all of you grinding wizards help me figure this out!

-Targetcaller

LockNut · Aug 12, 2020

Targetcaller said:
Big company came to us with a P.O. for around 5000+ 6 inch diameter parts. They are carbide and need to be +/-.0001 flat and within dims. Looking to take off .004 a side. No "fancy grinding" (radius or forms) at all here just a large number of parts needing to be very flat and mirror finish. Willing to do whatever it takes to get the job done.

Have experience with CNC Edm/Mill/Lathe/ect. Very new to CNC Grinding. What are some grinders that you all would recommend for this type of a job? Good company? Good models?

Thanks,

-Targetcaller

Some people can't read. That being said, that is 250 parts per day. Not going to happen without specialty machines and/or multiple machines and/or multiple shifts. New machines are in your future. I would not even look at Blanchard for this. Here is a good article in MMS, https://www.mmsonline.com/articles/grinding-carbide--a-niche-within-a-niche

This really is a niche market and not for the faint of heart.

1953chevB · Aug 12, 2020

LockNut said:
Some people can't read. That being said, that is 250 parts per day. Not going to happen without specialty machines and/or multiple machines and/or multiple shifts. New machines are in your future. I would not even look at Blanchard for this. Here is a good article in MMS, https://www.mmsonline.com/articles/grinding-carbide--a-niche-within-a-niche

This really is a niche market and not for the faint of heart.

6 inch diameter parts and flatness does not compute, that why a picture is worth 1000 words, don't be a shaft

1953chevB · Aug 12, 2020

when a customer would call me try to explain it words to quote a job, first thing out of mouth is send me print then lets discus.
and then I need time to study it, that's how I do business it's not personnel. when people make derogatory remarks it does not help the OP

CarbideBob · Aug 12, 2020

I wonder what this op sells for in this quantity 3-5 bucks a part? Maybe 7-12 with the mirror finish.
If you scrap a customer's part by less than a tenth do you have to buy it? This not a cheap blank.
How long of a run? Can you put the machine cost out 7 years and know it will stay running?
So many sources out there that can do this in steel or powdered metal, carbide, not so many.
Obvious is wafers but that is so way different one sided work.
Bob

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