EMPLOYEE WAS AT BELT 18 CONVEYOR HEAD PULLEY PREPARING TO CLEAN THE MAGNET THAT COLLECTS METAL COMING OFF BELT. EE DROPPED PLATE DOWN TO POSITION TRAY UNDER MAGNET. WHILE POSITIONING TRAY, PLA TE WENT TO DROP & EE REACTED BY GRABBING THE PLATE & DOING SO USED HIS HAND TO GRAB PLATE, HIS HAND STRUCK BELT ON HEAD PULLEY AND EDGE OF PLATE WHICH SLICED HIS RIGHT THUMB.