Grinding and cutoff discs for angle grinders

[old martParticipant @oldmart]

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?

[old martParticipant @oldmart]

[Former MemberParticipant @formermember19781]

[This posting has been removed]

[JasonBModerator @jasonb]

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 yetParticipant @notdoneityet]

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I don’t use many, so unless they are bought singly mine can go out of date – but they are stored carefully.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 martParticipant @oldmart]

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 I can destroy the entire stock of out of date discs now to prevent an accident and the bad publicity that would ensue.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 3Participant @nickclarke3]

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 2Participant @billdavies2]

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 yetParticipant @notdoneityet]

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 2Participant @billdavies2]

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 20Participant @marksmith20]

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 1Participant @martinhamilton1]

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

[VicParticipant @vic]

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 1Participant @martinhamilton1]

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

[old martParticipant @oldmart]

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

[Douglas JohnstonParticipant @douglasjohnston98463]

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

[VicParticipant @vic]

Have any of you tried Diamond discs for metal?

**LINK**

[old martParticipant @oldmart]

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 FarrParticipant @nicholasfarr14254]

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

[Former MemberParticipant @formermember25081]

[This posting has been removed]

[not done it yetParticipant @notdoneityet]

Amperage? Could be twice the UK value if you are on 110V supply.

Also depends on the disc diameter.

Most manufacturers make different ‘grades of machine, dependent on usage.

More info required. A lot more.

[HopperParticipant @hopper]

For typical light home hobby workshop use, the cheapest hardware store angle grinder is usually good enough. That's all I use at home. Bosch, DeWalt, Makita etc are much more expensive and suited to all-day every-day use on worksites and in commercial workshops. As always, you get what you pay for. So it depends on your usage and your budget.

A 4" (100mm) model will do most of what you want at home and is much safer than the rather scary 9" jobs etc that can cause very nasty injuries if they catch in the job and buck out of control.

Discs are much the same. Thin cutting discs designed to be used on the edge, and thicker grinding discs to be used on the face are commonly available at the local hardware store. In recent years some very thin cutting discs about 1mm thick have become available and are the cat's meow. Super useful.

Whatever you get, treat it with respect. They are a very rapid cutting tool and fling debris quite far. Eye protection is a must. Fire safety awareness from the sparks is a must too in a workshop full of oily machinery and rags etc. Best used outside if possible.

Edited By Hopper on 05/06/2022 08:28:30

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Jack, all the major high street names are very much comparable within their price ranges, but you may find one particular make is more comfortable for yourself to use. The only other thing is what your actual needs are, as a 110v type is normally used in industrial/commercial workshops and are generally more robust because they are very often used all day every day whereas a DIY type wont be made to such demanding work. The disc size will also depend on what work you will be using it for, but most DIY ones are 4-1/2" (115mm) amperage as NDIY says is dependant on the voltage used. Generally the more you pay, the better the machine you get which ever make you buy. I've used many different makes during my working life and I've found that Makita & Bosch ones suite my hands best and I would say I've liked the handling of Makita ones better. Like most things though, prices vary depending on who and when you buy from and whether they are promoting a particular brand and or model.

Regards Nick.

[Pete RimmerParticipant @peterimmer30576]

My advice is get a 5" grinder. If you're using the thin cutoff discs you'll get a lot of extra use from that extra 1/2" of disc and the extra 1/4" depth is very handy sometimes too. The smaller the diameter of grinder, the more disc is wasted if you're cutting stuff like sheet where the housing will foul the work.

The 4" discs have a smaller hole than the rest (4.5", 5" and 9" are all the same) so I would avoid that because it limits your choice of disc.

You can use a 4.5" disc on a 5" grinder no problem and if you choose your model carefully you'll find a good one with a smallish gearbox housing for maximum disc usage but you can't put a 5" disc on a 4.5" grinder without removing the guard.

The cheap ones are 'OK' for light use but they don't like heavy cuts and the blade guard release lever tends to be bulky so it's the first thing to foul the work.

[egaParticipant @ega]

I did get a 5" (125mm) angle grinder some time ago but only because I couldn't find a 7" machine.

My angle grinders all have a short lead with connector so that unplugging to change disc or machine is quick and easy.

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