The hazard
Machines do not know the difference between the material and your hand. Moving parts can crush, cut, pull in or throw things faster than anyone can react. Guards are there because nobody can stay perfectly careful every minute of every shift. A missing or bypassed guard can turn a normal day into a serious injury.
The action
Rotating shafts, belts and chains can grab a loose sleeve, a hood string, jewelry or long hair and pull you in. Wear fitted clothing, take off rings and chains, and tie back long hair. OSHA's power transmission rule requires regular oilers to wear tight-fitting clothing, and machinery must be oiled when it is not in motion, wherever possible. (29 CFR 1910.219(p)(7))
ASK THE CREW
What types of guards are on the machines in our area, and are any of them removed, propped open or worked around?
From the talk: Machine guarding. Read it in full, free, with the questions and the sign-in sheet.