Thread: Metal dust - how bad is it

I don't grind metal with the grinder often. But when I have done so without a mask, I have been astonished at the amount of black dust particles expelled when I blew my nose. Being more of a woodworker I seem to forget about metal particles.
Interesting experiment Bob.

Good Morning Bob

Thanks again for another fascinating experiment.

Like most, I knew the stuff clogging my nose was not good for me, and I always wanted to avoid flying shrapnel; But am probably guilty of removing the face mask too quickly as I want to breathe.......

A couple of questions about your results:

• There is a kink in all the graphs at about the 4 minute mark - any insights yet?
• Noting that, by weight, the airborn waste is about 10% "grinding sand" and about 90% metal, is the "ginding sand" concentrated in the larger particulates or evenly spread? Is the finer stuff mainly metal? Does it matter?

Will watch to see how you develop this experiment. Thanks



Fair Winds

Graeme

Originally Posted by GraemeCook

Good Morning Bob

Good afternoon.

Thanks again for another fascinating experiment.

No worries, although I can't really do anything else in my shed while doing these experiments I still like doing these them.

Like most, I knew the stuff clogging my nose was not good for me, and I always wanted to avoid flying shrapnel; But am probably guilty of removing the face mask too quickly as I want to breathe.......

That's more or less what I was trying to find out.

A couple of questions about your results:

• There is a kink in all the graphs at about the 4 minute mark - any insights yet?

The kink is probably cause by me. Except for when I am writing down the results after each reading I stay away from the area of the shed where the dust has been generated and the sensor is located.
In the case of the kink I may have just walked too quickly up to the measuring instrument and dragged a bunch of cleaner air with me. Even gusts of wind blowing past a leaky building can suck dust out of a shed or fluff sedimented dust up inside a shed.

• Noting that, by weight, the airborn waste is about 10% "grinding sand" and about 90% metal,

Not necessarily, I'd say that most of the ground metal is too big to be suspended and it falls to the ground immediately.

is the "ginding sand" concentrated in the larger particulates or evenly spread?

I don't know but read on. I was wondering if I could make a magnetic filter around the detector by setting up a 3D array of magnets around it so as to trap magnetic particles this preventing then getting into the detector. That way I could discriminate between magnetic and non-magnetic material. OTOH the magnets could drag more magnetic materials towards the detector.

Is the finer stuff mainly metal? Does it matter?

Probably at the beginning there is significant metal in the air but since metal should settle out faster this will leave a greater proportion of the grit from the wheel suspended in the air. There is some evidence for this in the large particle (orange) curve. You can see that curve drops quick at first and then levels out. It's almost like a two step curve. The finest dust (blue) curve does not do this suggesting that it is mainly wheel grit.

Does it mater, yep, it really does matter. We can ingest and breathe in a substantial amount of iron but the materials in the wheel are not so friendly. However, if it's a Cobalt alloy it might be significant. The material with the greatest potential health threat in a cutting wheel is the fibreglass.
It's a complicated system that needs a careful analysis. I need to do some maths and model some possible situations to see how close to OHS limits this sort of cutting activity goes.

Will watch to see how you develop this experiment. Thanks

It has already progressed - have a look at this one
https://www.woodworkforums.com/f65/metal-dust-measurements1-183227

Keep asking the good questions, it's good to see someone is awake

Originally Posted by BobL

Good afternoon.


No worries, although I can't really do anything else in my shed while doing these experiments I still like doing these them.


That's more or less what I was trying to find out.

The kink is probably cause by me. Except for when I am writing down the results after each reading I stay away from the area of the shed where the dust has been generated and the sensor is located.
In the case of the kink I may have just walked too quickly up to the measuring instrument and dragged a bunch of cleaner air with me. Even gusts of wind blowing past a leaky building can suck dust out of a shed or fluff sedimented dust up inside a shed.


Not necessarily, I'd say that most of the ground metal is too big to be suspended and it falls to the ground immediately.


I don't know but read on. I was wondering if I could make a magnetic filter around the detector by setting up a 3D array of magnets around it so as to trap magnetic particles this preventing then getting into the detector. That way I could discriminate between magnetic and non-magnetic material. OTOH the magnets could drag more magnetic materials towards the detector.



Probably at the beginning there is significant metal in the air but since metal should settle out faster this will leave a greater proportion of the grit from the wheel suspended in the air. There is some evidence for this in the large particle (orange) curve. You can see that curve drops quick at first and then levels out. It's almost like a two step curve. The finest dust (blue) curve does not do this suggesting that it is mainly wheel grit.

Does it mater, yep, it really does matter. We can ingest and breathe in a substantial amount of iron but the materials in the wheel are not so friendly. However, if it's a Cobalt alloy it might be significant. The material with the greatest potential health threat in a cutting wheel is the fibreglass.
It's a complicated system that needs a careful analysis. I need to do some maths and model some possible situations to see how close to OHS limits this sort of cutting activity goes.


It has already progressed - have a look at this one
https://www.woodworkforums.com/f65/metal-dust-measurements1-183227

Keep asking the good questions, it's good to see someone is awake

Thanks Bob a detailed investigation as always. I will follow this with interest

Originally Posted by shedman

Thanks Bob a detailed investigation as always. I will follow this with interest

Me too.



Fair Winds

Graeme

I too have done/do my fair share of grinding/cutting using grinding/cutting wheels, always thought that it can't be good to be breathe all these particles so I have been reading with interest.


Pete

Most interesting Bob, And thanks for the info.

We don't really take enough notice of any kind of dust.

Spalted or fungus ridden wood can be deadly. I had a tree lopper here who was in a poor way
due to fungus riddled stumps he had ground.

Garden compost and bagged garden soils are also problematic and the bagged soils have warnings on them.

Over the weekend Ana and i had charge ( I won't say control !! ) of a couple of the grandkids. We took them to a gym for an hour to work off some energy. The place was full of feral kids AND dust!! The dust in the
air was very visible in the sunlight and at the end of the hour I had quite a stuffy nose.

My mind drifted off reading about the results.....sorry Bob, but I drifted to a Nursing Home in 30 years time.....he I am sitting in the sun with a blanket over my lap and wheezing to breathe and saying "I knew I should have listened to BobL".
Its very easy to be complacent/lazy and not observe proper PPE. As I may have said before, when I started my Carpentry Trade on 1970 friction discs were just being released for sale. With these things and a Black and Decker powersaw you could cut through concrete and fibro!!!! No eye protection, no ear protection and definitely no breathing protection. You would set your self up with the saw take a deep breathe and away you go and only stop when you couldn't see what you were doing for the dust or you ran out of breathe. One of my jobs as an apprentice was to shoot brick ties on to concrete walls for the bricklayers using a Ramset powder actuated gun. Three days a week nearly every week. No eye protection, no ear protection and the result.....tinnitus (I thought the ringing in my ears was "normal" until a hearing test told me other wise only 15 years ago)

a couple of things to think on.

First and most important is the nature of the dust and not just the size of the particles.

as has been mentioned most of the waste produced cutting steel by any method is much heavier than the waste we would find cutting wood or composites....therfore it will drop out of the air considerably faster......thus reducing the over all dust load in the air considerably.

as also has been mentioned the majority of the dust will be iron and carbon...unless of course exotic metals are being cut....

while there may be non metal dust from the grinder wheels, this persentage is small.

the critical difference is there is very little in the dust in the way of toxins ( as would be found in problem woods) and there is very little in the way of persistant particles or of an unfortunate shape like found in fibreglass or asbestos.

While there will most certainly be some risk, it will be much lower than many other dusty operations.

I don't have the figures or the sources.....but the OHS statistics I expect to show a lower incidence and severity of dust related injury in the metal work industry (as long as sand blasting is excluded..that is a whole other story).


The single biggest factor in this whole equasion however is the grinder......the grass roots tradesman seems to be obsessed with the grinder....it seems to be the go to tool for all sorts of tasks......mostly because it is seen as quick and cheap.

Many people I have worked with a all to ready to reach for or offer a grinder for the smallest and simplest tasks.

just yesterday I wanted to cut 2 pieces of 20mm threaded rod......my co-worket without hesitation offered his battery powered angle grinder....I said no thanks and cut the pieces with a sharp hacksaw and cleaned up the small amount of bur with a file.

truth to tell though, once the whole operation including clean up and risk is factored...the grinder and all its abrasive wheel cousins are expensive, slow and dangerous...and much of the time inappropriate.

The best thing we can do to reduce a whole range of risks, is to use alternatives to the grinder where possible.

some examples.

Cutting round pipe with a rotary pipe cutter is fast, clean & quiet..though most will reach for a grinder.

Cutting small pieces of metal will a hacksaw realy is quick, easy and produces almost no airborne dust.

Cutting light sheet metal with an abrasive wheel.....OH please..there are so many better ways.....hand, electric or air powered metal sheers, ripping with wire, score and snap..and they don't burn the plating or paint near the cut.

A good sharp cold chisel, is a very quick, clean and effective tool in the right hands...but most will reach for the grinder.

My local steel supplier that also sells aluminium, used abrasive wheels to cut both......like lots every day.......I don't grasp why they do not use a fine tooth blade for aluminium like I do and for the volume in question why they are not using a cold saw or a lubricated metal cutting band saw to cut the steel.....it would be cheaper on blades alone.

The grinder and abrasive wheels most certainly have their place...but in my view and the view of the OHS establishment.....they are very much overused.

cheers

Just another thaught.

An indicator of the scale of the problem.
go to a workshop where there is a lot of metal working going on...and not much else..no wood work and definitely no sanding or body work.

have a look arround...particularly look at the walls and on top of stuff....there will be dust, but in no where near the proportions that you would expect in a wood working shop.

cheers