2y ago

Help me understand this effect

This is an abrasive disk, rotating at 1500 rpm. When I shine my flashlight at it, it carries the glow with it, approximately halfway around the disk. What am I seeing happen here?

18 comments

I'm guessing it's an aluminum oxide abrasive? The abrasive is flourescing due to the little bit of uv coming out of the LEDs.
You might find this interesting, if you are grinding iron or steel then the grinding surface may not flouresce due to the iron bonding with the aluminum oxide.
- This seems like a perfectly reasonable answer. OP! You could probably test this by changing the type of light you're using. Try a red laser pointer as a control, and a black light wand (the sort they use to detect counterfiet bills), and see what happens.
  
  Sadly I have neither of these things available on hand to test that theory but I can at least confirm that the abrasive wheel is a ceramic alumina.
  Actually NVM, I found a laser pointer and it has no effect, though it is admittedly quite dim.
- I saw "iron", "aluminium" and "oxide" and I briefly assumed you were trolling until I looked again to check which one was the oxide.
It sounds like you got the answer to your question, so I need to ask, what the heck weird kind of flashlight is that?
- It's a cheap LED pen light, they hand them out like candy where I work. Most of us have our own flashlights anymore.
What effect are you talking about? Is there a frog clinging to the underside of that stone, and you try to coax him out with a flash light?

18 comments