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Is it safe to use old large surface grinder wheels? 24"

rickseeman

Cast Iron
Joined
Oct 7, 2014
We has several large (up to 24") surface grinder wheels that are over 15 years old. Somebody insinuated that they shouldn't be used because the resin gets old and looses it's bond. I've never heard this before. What do you think? Thanks.
 
You mention me one thing in machining that is not dangerous please
How much danger you want to endure is up to you
I would ring them a
Not all grinding stones are resin bond btw
Many are vitrified by backing at high temperatures up to 1200Dgr C

Peter
 
Norton recommends using up almost any wheel within a 2 year period from the date of manufacture. Here's a clip from their website:

"It has always been Saint-Gobain’s recommendation that Resinoid Bonded grinding wheels be used up within 2 years from the date of manufacture. This recommendation assumes that Resinoid Bonded grinding wheels have been stored under ideal storage conditions. It may be true under ideal storage conditions Resinoid Bonded grinding wheels can survive without any degradation in strength for well over two years. However, it is always wise to suspect any wheels over two years old and have them reinspected or re-speed tested to determine if there has been any degradation in strength. If the wheels are stored under less than ideal conditions, they may have a much shorter shelf life depending upon the severity of storage conditions.

These same comments also apply to rubber and shellac bonded grinding wheels. As for vitrified grinding wheels, the shelf life is less influence by humidity and adverse storage conditions as compared to resinoid, rubber or shellac, but even vitrified grinding wheels do not have an infinite shelf life."

They recommend sending in almost any wheel over 2 years old for speed and bonding testing. The downside is that shipping both ways, and disposal of any defective wheels is the responsibility of the customer. In most cases this process isn't economically feasible. The cost of shipping and disposal for most smaller sizes is close to the price of a new wheel.

I have dozens of vitrified wheels, some of which are going on 10 years old. I ring them before each use, and have yet to have a problem with any of them.

Here's a link to the information on the Norton website:
Shelf Life of Grinding Wheels | Norton Abrasives
 
1st - Is it resin bonded?

If YES - smash and bin it

If NO - do the ring test as per eKretz ……..and still stand clear when you first switch on.
 
1st - Is it resin bonded?

If YES - smash and bin it

If NO - do the ring test as per eKretz ……..and still stand clear when you first switch on.

We used lots of 20" resin bonded wheels in the past on large swinging arm type grinding machines. They were used for fettling castings. It was my job to change new wheels for old and then smash the old wheels. As far as I am aware you should always break any wheels you dispose of to prevent idiots re-using them. It was impossible. Lots of wheels you can break by simply dropping them down flat from chest height onto the floor. These just bounced, I tried hitting them with a sledge hammer - no joy there either. I ended up throwing them unbroken into the skip.

Vitrified wheels are another story and I'd be very careful about using pretty old ones. Any time I switched a grinding machine on I always stood out of line with the wheel as a matter of course.

Regards Tyrone.
 
Do they have 'born on' dates? I often suspect as lot of stuff I buy has been on a shelf for many years. Belts and seals are a good example.....been baking up a 130 degree rafter for a decade then sold over the counter as 'new'.
 
I worked for a co. that built a grinding wheel exploder / tester for Norton It was pretty cool 2 2" thick rings i believe the inner was not mounted down they had fun getting the direct drive 18000 rpm motors to to like the forces when things let loose .
 
First, know what you have. resin bonded wheels do deteriorate. Vitrified wheels are , as their name indicates, made of glass, with abrasive grains mixed in. Their shelf life is comparable to your glass windows. Replace them at similar intervals.
 
TDmidget said it best.

I've used plenty of old stock vitrified wheels. The Federal Stock System stumbled on a trove of WW II era vitrified grinding wheels that fitted our large Mattison surface grinder. The boxes were dusty but the wheels inside pristine. Everyone I used rang sweet and true and they were 40 years old at the time.

If they were used and had stale coolant dry in the porosities, there may be chemical voodoo that would attack the vitrious bond but, somehow. I don't see it happening. Remember, grinding wheel safety is one of those low probability/high consequence deals.

My advise would be use new old stock vitrified grinding wheels that rang satisfactorily but trash used vitrified wheels exceeding 5 years since their last use.

In my experience, resin bonded wheels are rarely used in general purpose machine grinding. You generally find them used in glass fiber reinforced cup wheels for angle grinders and abrasive saws, or in more refined applications like thread grinding, super-abrasives, form grinding etc. I"m not aware of shelf life restrictions applying to resin bonded wheels in unused condition of for that matter vitreous bond. I suspect the Norton caution is more liability avoidance/cynicaly self-serving (tell the customer to toss perfectly good wheels so we can sell them more) than advise based on impartial product experience studies.

As always in using grinding wheels, work safe, wear eye protection, replace guards removed for machine servicing, inspect/ring wheels before placing them in service, etc
 








 
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