So I was asked to look into a little problem this morning. I was told that the wire cup brushes we are using have been spitting out wire like crazy. We received this complaint from a few guys, not just one. Along with this problem I was informed that some of the new style flap disc's that we started using were coming of the grinder and hitting people, both the operator and bystanders. So I took one of the disc's that had come off and went to the grinder that had this happen last. He took the new disc off and handed me the grinder. I screwed the disc in question on and asked him for his wrench so that I could tighten it. Guess what? He did not have one. The wrench supplied is the spanner style and will not work in this application. So I go to the next guy in line. Same thing, no wrench. Come to find out, not a single grinder or welder could produce the wrench needed to tighten these disc's properly. These are all brand new grinders/tools and are running at full capability. 12,000 RPM. The disc's are rated at 13,300 RPM. Hand tight and/or snug will not cut it. It may result in the disc being thrown off. The correct wrenches are being purchased.
As for the wire cup brush, well yes I would imagine it is throwing wire all over. It is only rated at 9,000 RPM. Go figure. Correctly rated wire cup brushes are being purchased.
So anyways, there is another safety presentation to add to the arsenal.
Stay safe and use the proper tools for the job, and make sure the disc/wire brush you are using is rated at or above the tools rating.
jrw159
Anything flying apart is bad but I think disintegrating wire cup brushes are among the worst. The flap disk and grinding disks are usually shielded by the guard but the cup brushes extend past the guards. It seems that those flying needles never hit you sideways - always point-on, or so it seems.
When I was doing boiler inspection we would have guys using the wire wheels to clean off the tubes for UT. One of the wires flew off and stuck in his leg, this was not uncommon. A few days later he was in the hospital with a high fever and ended up with a 9 day stay due to bad infection.
There are some that seem to come apart very easily, and others that hold up well.
Have gone to take carharts off at the end of the day and found dozens of little spikes all over the front. Hard on the hands if you don't realize they are there and rub the front of your coveralls.
Have a Great Day, Brent
I don't know how many people offshore that I've screamed at, at the time that they are going to spool up a hyd grinder with a disk that has already been in the water to test the grinder. That or the ones that put 3000 rpm disks on an air grinder that will do 15,000 rpms. The water slows everything down so you can use the lower rated disks underwater.
Charles Welch
On those grinders where the wheel flys off, its not always an RPM issue especially on air driven grinders.
It's how fast they de-accelerated that sends them flying.
The electric ones aren't as bad but they can still send one sailing if you fail to tighten it good.
RonG,
Good point, I agree. I do beleive that the deceleration of the air tools (even new) combined with the lack of proper tightening resulted in them coming off.
jrw159
That has to be it. The acceleration will tighten a grinding wheel nut.
I've got the Metabo with the quick release nut, and if you press the yellow thumb button when you've got the type of wheel that goes straight on the arbor (especially a cup brush), the brush will predictably come flying off.
OTOH, with the nut supplied by Metabo, it will open enough to loosen, but never come off (there's just enough friction created by this spring clip thingy that stops it).
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