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
Every machine with moving parts has danger points. OSHA's general machine rule lists hazards such as the point of operation, ingoing nip points, rotating parts, and flying chips and sparks. One or more methods of machine guarding must protect the operator and other employees in the machine area from them. Before you start, know where these points are on your machine. (29 CFR 1910.212(a)(1))
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.