THE EMPLOYEE WAS REMOVING A WORN TRACK ROLLER ON A CAT D6 DOZER. AFTER DONNING PPE AND REMOVING THE BUSHING BOLTS, EE PLACED THE COLD CHISEL INTO THE LOOSENING SLOT AND STRUCK THE CHISEL WITH THE HAMMER. THE CHISEL SHOT BACK INTO EE'S FACE SHIELD AND LACERATED EE'S LOWER LEFT LIP.