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Speaking of Precision

Speaking of Precision is a knowledge preservation and thought leadership blog covering the precision machining industry, its materials and services. With over 36 years of hands on experience in steelmaking, manufacturing, quality, and management, Miles Free (Milo) Director of Industry Research and Technology at PMPA helps answer "How?" "With what?" and occasionally "Really?"

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Grinding Advice You Probably Didn’t Know

Posted August 19, 2014 10:30 AM by Milo
Pathfinder Tags: finger cots gloves grinding tips

Our post on No Gloves When Working on Grinders has prompted a number of responses.

Here are some additional reasons why you should not even need gloves when working on grinders and grinding machines.

Issue: "There are sharp edges or burrs that will cut me if I hold the part. The grinding will be to remove the burrs."

Response: Use a file to knock down the burrs so that you can safely hold the part for grinding. Or use leather finger cots to grip the part for grinding.

We permitted these for use on belt grinders for holding small parts.

Issue: "The part gets too hot to hold."

Response: Then you are grinding wrong. Here is a list of some of the things that can go wrong by letting the heat of grinding get out of control:

  • Remove the temper from Steel. Especially on tools, loss of temper means loss of tool hardness and edge life. A drop from Rc63 to about Rc48 for a couple of tenths (0.0002-0.0005) can contribute to side wear and edge failure.
  • Crazing or checking on Carbide can be caused by burning during grinding.
  • Work Hardening. Overly shiny surfaces are usually the clue that work hardening has occurred.
  • Creation of untempered martensite.

Untempered martensite can be formed in high carbon and alloy steels by getting high surface temperature from grinding- red heat- then quenching in water.

  • Untempered martensite is very brittle and reduces toughness.
  • Keeping the work cool continuously while grinding is an important aspect of preventing damage to work, the wheel, and injury from occurring to the worker. Hogging off material and infrequently quenching is a great way to destroy a tool by grinding
  • Water needs to be plentiful to absorb the heat from grinding, and frequently used to reduce heat buildup in the work.
  • Take multiple small passes and cool in between in a large bath of water while grinding to minimize heat build up.

Of course, wearing the required PPE, making sure the grinding wheel is properly dressed, all guards are in place and properly adjusted are also key to safe grinding in our shops.

Bottom line: If the work is too hot for your fingers, it may be approaching the danger zone regarding loss of mechanical properties and function in end use.

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#1

Re: Grinding Advice You Probably Didn’t Know

08/19/2014 11:55 AM

I'm probably going to regret asking.

What about holding the workpiece with another tool... Vise-Grip, for example?

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#2
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Re: Grinding Advice You Probably Didn’t Know

08/19/2014 4:30 PM

I've done the same thing with no regrets.

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#3

Re: Grinding Advice You Probably Didn’t Know

08/19/2014 4:36 PM

Here is something I did with dire results. I was tuning up my chain saw so I figured I would clean the crud off the chain by holding it against a wire wheel. The wire wheel grabbed the chain and whipped it round and round taking flesh along with it. That was around 2 years ago and I have never touched that chain again. I now know there are better ways to clean a chain and a wire wheel is not one of them. Thinking back, gloves might have protected my hands better.

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#8
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Re: Grinding Advice You Probably Didn’t Know

08/20/2014 2:35 PM

The gloves may have protected your hands. But more likely not and maybe caused more harm. Some of the worst cuts I've seen are where a saw blade has caught the fabric of a glove. It then sucks your hand in.

Grinding steel it's hard to feel the heat generated by grinding with gloves on.

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#4

Re: Grinding Advice You Probably Didn’t Know

08/20/2014 5:01 AM

When dressing lathe tools I always hold the tool in bare hands, that way you never let it get too hot.

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#5

Re: Grinding Advice You Probably Didn’t Know

08/20/2014 5:23 AM

I wonder what the requirements are for injury insurance to pay out when NOT using gloves for what an insurance company may consider as dangerous work?

It may be seen as the fault of the worker if an accident happens with no gloves if the regulations require them, maybe formulated so simply as "safety equipment", so that insurance can be removed if they were not worn in the even of an accident!!

You are at the mercy of such companies....a close look at the small print is needed in each and every case....

I would rather risk an accident WITH gloves, rather than none....I think that would be erring on the side that insurance cover would not be invalidated.....

What do the rest of you Guys think of this in a "real world situation"?

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#6
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Re: Grinding Advice You Probably Didn’t Know

08/20/2014 9:05 AM

The real world, where we all exist. With or without gloves, that is the question. Every jurisdiction has it's rules. We are governed by OHSA(Occupational Health and Safety Act) which clearly states the "glove, jewelry, loose clothing and long hair" shall not be used or worn when operating "rotating" equipment. If someone has an accident as a result of any of these, guess who gets fined. You can make arguments all you want but the law is the law. Best anyone can offer is the proper type of gloves that reduce the risk of entanglement while still offering some protection from other risks.

Personally, I prefer not to use gloves when grinding or any other power tool/equipment use. Yes I get a few nicks and scrapes, but I like to be able to feel the workpiece.

I have seen a few finger amputations(wrenching them out of their sockets) involving gloves and rotating equipment and they are not pretty. I make that point with all my employees and they seem to take heed. Haven't had an accident involving rotating equipment and gloves for the last 20 years. ♫♫♫

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#7
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Re: Grinding Advice You Probably Didn’t Know

08/20/2014 10:26 AM

The stuff we work with is quite small so gloves are just a hindrance. I guess it's just a case of horses for courses.

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#10
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Re: Grinding Advice You Probably Didn’t Know

09/28/2014 12:06 AM

Yes, grinding gloves are reknown finger retreaval devices; lose a finger? Check your glove

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#9

Re: Grinding Advice You Probably Didn’t Know

08/26/2014 2:39 PM

Here at the plant we have a Scotch-Brite (tm) wheel used for deburring cut parts, and when working with it, I prefer the gloves, because I simply do not like the 'road rash' on my knuckles when a piece slips and I end up with my hand against the wheel. The guards aren't a problem, and the parts are typically that T-slot aluminum, so there are so many edges around tiny holes, that wheel-deburring is simply faster and easier than pulling out a tiny file to knock off all the little burrs on the piece.

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#11

Re: Grinding Advice You Probably Didn’t Know

09/28/2014 2:49 AM

I guess that knowing how to use gloves in such situations is part of the deal if you want to use them.

I have never lost a glove (or a finger!) while grinding or burnishing, not that I do either often nowadays, but years ago it was almost daily. I was taught, about 40 years ago, to use gloves, seemingly "properly" it would appear, though what properly is I have no idea anymore, I just "do it!"...

Leaving this blog now....byee.....

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