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Grinding and cutoff discs for angle grinders

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old mart14/11/2019 19:38:53
802 forum posts
77 photos

One of the volunteers at the museum drew my attention to our stock of discs for angle grinders. There is a date on the metal centre of each disc. This is not a date of manufacture, as the newest ones which were bought only a year ago have 2022 on them. Most of the others have dates of 2017 of older. I had no idea that these items might have a limited life, some of my own were bought in about 2002, when I bought my angle grinder.

Are these dates relevant? Do we have to destroy them even if they are unused?

3404614/11/2019 19:45:59
796 forum posts
6 photos

The reason these discs have an expiry date is due to the resin used in the manufacturing process. The resin is used to bond the abrasive, and over time, this resin will absorb moisture, leading to deterioration in the cutting or grinding disc.

Using a disc outside of its expiry date will lead to disc failure and a high probability of causing severe injury to the operator and anyone nearby. Retailers also have the responsibility not to sell discs that are out of date.

Hope this helps

Bill

JasonB14/11/2019 19:48:38
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Moderator
16573 forum posts
1772 photos
1 articles

Used to be that only trained people could change a disc and part of that training was that you should not use expired discs, would have thought in a place like a museum it would be the same as on a building site. Been a while since I did the course.

not done it yet14/11/2019 21:24:57
3582 forum posts
15 photos

It is likely H&S at work. I expect in-date discs could have been stored in damp conditions.

I don’t use many, so unless they are bought singly mine can go out of date - but they are stored carefully. I would not use a cutting disc (much) beyond its use-by date, but grinding discs are generally not quite as risky. Again, it is my risk - and without third parties in the vicinity.

Checking the date is the first thing we do if discs come up at auction.

old mart14/11/2019 21:42:32
802 forum posts
77 photos

That's why I asked, having never thought about that subject before. I can destroy the entire stock of out of date discs now to prevent an accident and the bad publicity that would ensue.

Nick Clarke 314/11/2019 21:47:47
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423 forum posts
12 photos

Used to work with a retired toolroom grinder, in a place where we sold the disks and he hated the things and always told any customer who bought any about them shattering and embedding themselves in a concrete pillar in his toolroom.

Put a bit of a dampener on counter sales, but he was sincere!

Bill Davies 214/11/2019 22:13:05
120 forum posts
10 photos

It is the resinoid wheels being discussed:

https://www.nortonabrasives.com/en-us/resources/expertise/shelf-life-grinding-wheels

The vitrified bonds seem to have an indefinite life. In my first engineering work, formed wheels Al. oxide wheels were kept for the next time a job came in, which might be years. They certainly don't mind coolant pouring over themselves.

I used to give mounting of grinding wheel training earlier in my life. When I moved on to a new employer, this was not accepted and I had to receive training. Later, working in a college, I was told I needed training (just to remount exisiting wheels on a cylndrical grinder and a surface grinder), but there was no money for this, so the machines became unused. There seemed to be no concern for replacing wheels on the offhand grinders, though. H&S is important, but those overseeing it seem to often have extremely firm views.

not done it yet14/11/2019 22:38:44
3582 forum posts
15 photos
Posted by Bill Davies 2 on 14/11/2019 22:13:05:

It is the resinoid wheels being discussed:

...

I think the thread title specifically refers to angle grinder cutting and grinding discs.

Bill Davies 215/11/2019 00:49:16
120 forum posts
10 photos

It does; grinding and cut-off discs. As I understand it abrasive wheels for angle grinders are made using the same technologies as those on other grinding machines. Since we use a variety of types in our workshops, I thought useful to draw attention to the fact that only certain types suffer from a relatively short lifespace, used or unused.

Bill

mark smith 2015/11/2019 09:43:12
619 forum posts
313 photos

Recently cut up some hss using a thin diamond disc for angle grinder , much better than the resin bonded ones and far less mess. But didnt work well on brass ,they all gummed up with brass particles.

Martin Hamilton 115/11/2019 09:44:01
145 forum posts

Norton state that resinoid discs have a shelf life of 2 years, this may be further reduced if stored in less than ideal conditions.

Vic15/11/2019 10:28:30
2333 forum posts
12 photos

I’ve just had a look at the offerings at Screwfix and whilst some discs clearly have a date marked on them I can’t find anything similar marked on these Norton ones?

**LINK**

I’m assuming each disc must be marked individually.

Martin Hamilton 115/11/2019 11:16:44
145 forum posts

Google Shelf life of Norton grinding wheels, it will take you to Norton's site where they give such info.

old mart15/11/2019 19:49:43
802 forum posts
77 photos

I looked at lots of adverts for angle grinder discs, and not one seller was admitting to the date of expiry.

Douglas Johnston15/11/2019 20:13:42
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642 forum posts
32 photos

This seems to be a well kept secret. I have never seen a reference to this and was totally unaware of the issue until now. I will certainly check out my stock and bin any that are too old. For such a potentially dangerous item there should be a bold warning on the discs themselves along with a reminder on the packaging.

Doug

Vic15/11/2019 22:13:24
2333 forum posts
12 photos

Have any of you tried Diamond discs for metal?

**LINK**

old mart16/11/2019 17:35:24
802 forum posts
77 photos

At the museum today, I destroyed all the grinding and cutoff discs which were out of date, including my own which were the oldest. All that are left are about 8 Dewalt cutoff discs which have 2021 on them. My little 76mm discs for the 12V Parkside angle grinder have a date of 2022. I also have some Parkside 76mm general purpose carbide edged metal discs which also have the 2022 date on them, despite having an indefinite lifespan.

Diamond discs work for metal, but aluminium may clog them, and steel and cast iron will reduce their life as ferrous metals have an affinity for carbon, which means the diamonds dissolve in the iron when they get hot.

Edited By old mart on 16/11/2019 17:38:57

Nicholas Farr17/11/2019 14:46:07
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1998 forum posts
958 photos

Hi, I have several disc that are out of date, some of which were made before dates were put on them. While I'm not suggesting that anyone should disregard these dates, I personally have no qualms about using them in my own garage/workspace, I would not use them though in any employment environment however, as I would not be covered by any insurance if I had an accident while using one, regardless whether the disc caused the accident or not. I have had many discs fail while using them during my employment, even though they have been in date. Normally they'll fail if they happen to snag, but it is always important not to put oneself in the line of fire and to make sure that the guard is always secure and adjusted properly. It is also always important that any disc that you are about to use, whether it's brand new or used, is not warped or split etc. and that the steel piece in the centre hole is intact before you start it up and you should unplug your machine before changing any disc. All appropriate PPE should also be worn/used while working with angle grinders, even if it is only for a moments use.

Regards Nick.

Edited By Nicholas Farr on 17/11/2019 14:53:04

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