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Centerless grinding of carburized parts

Centerless grinding of carburized parts

Centerless grinding of carburized parts

(OP)
Hi all,
I've been given the task of figuring out how to centerless grind some of our parts in-house.  It's a sleeve roughly 4" in length, .7500/.75005 12Ra finished OD, with a .4995/.5005 finished ID. They are made from 9310, with a case depth of .035/.045 and hardness of 59/61Rc, core hardness of 32/44Rc.  They also have to be nital etched afterward.  I'm having a difficult time finding any information on the internet or in literature.  I have a limited number of setup pieces, so any advice on speeds and feeds would be helpful.
Thanks in advance!

RE: Centerless grinding of carburized parts

Do you currently have centerless grinding equipment in-house, and an experienced operator?  You shouldn't need more than a handful of parts for your operator or machinist to get it figured out.   

RE: Centerless grinding of carburized parts

(OP)
We have two Royal Master TG-12X4 centerless grinders. Calling our operators experienced would be a stretch.   

RE: Centerless grinding of carburized parts

How much material do you have to remove?  Your best bet would be to start with the grinding wheel manufacturers for a baseline point to start.  Half a tenth can be a pretty tall order for inexperienced operators.  If the machines are in good shape, they'll hold it, but it definitely takes the right setup.   

RE: Centerless grinding of carburized parts

uPnORT

Is your diameter a typo?
.75000-.75005
is .7500-.7505 which is grinding tolerance

because even seasoned machinist grinders are are going to have a tough time with this job.

this is grind & lap tolerance.

grind with a soft wheel j or k 80 grit
first part of the machine must temper etch inspect
to make sure it not over tempered or reharden.

RE: Centerless grinding of carburized parts

(OP)
Yep, typo, sorry.  The tolerance is .7500/.7505.  I've been told we that we have an I wheel for the machine, but I haven't been able to find it yet.  There is .002/.003 grinding stock.

RE: Centerless grinding of carburized parts

Unless you have a lot of parts you might want to look at doing these parts between centers on a cylindrical grinder
== set up etc is less of an issue with cylindircal grinding and you should be able to sneek up on you size -- it should also solve the issue that you don;t mention which is relationship of to bore to the OD.

A.R. "Andy" Nelson
Engineering Consultant
anelson@arnengineering.com

RE: Centerless grinding of carburized parts

(OP)
We have to maintain runout of .001 between the ID and OD.

RE: Centerless grinding of carburized parts

.002-.003 stock is light. the parts must be straight & round w/i .001 before grinding.

also the bore must be concentric prior to grind otherwise
it will be out of tolerance.

there should be .007 min stock total.

Saberblue has a point.
it will be easier to grind between centers, however
the parts must run true to centers before grind.
it is possible to true up the centers to the od & bore prior to grind,

it is also possible to grind centerless, but the operator must be seasoned. or a bunch of scrap is possible.

 

RE: Centerless grinding of carburized parts

UpNort,
   You may want to call a bearing manufacturer.  I know that they use centerless grinders to grind carburized parts all the time to tolerances in the millionths of an inch.  They may have some guidelines for you.  Just a thought.

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