Abstract: AT APPROXIMATELY 12:30 PM ON JANUARY 19, 1988, EMPLOYEE #1 RETURNED FROM BREAK TO CONTINUE GRINDING SMALL STEEL CASTINGS. THE CASTINGS WERE HELD IN PLACE BY A VISE ON THE WAIST HIGH WORK BENCH. EMPLOYEE #1 WAS USING A CHICAGO PNEUMATIC RIGHT ANGLE PORTABLE AIR GRINDER. IT WAS RATED AT 4500 RPM WITH A POSTED LIMIT ON THE ID PLATE OF A SIX INCH ORGANIC WHEEL OR A FIVE INCH VITRIFIED WHEEL. THE GRINDER WAS EQUIPPED WITH A SA1T TYPE 27 METAL WHEEL (MODEL A24R) RATED AT 6600 RPM, SIZE 9 BY 1/4 BY 8 INCHES. THE GRINDER WHEEL WAS NOT GUARDED DESPITE CAUTION WARNINGS ON THE WHEEL AND PORTABLE GRINDER. THE WHEEL WAS ACCIDENTALLY BROKEN DURING USE. FLYING FRAGMENTS CAME BACK AT THE OPERATOR, SHATTERING AND PIERCING THE APPROVED FACE SHIELD AND ENTERING EMPLOYEE #1'S MOUTH AND THROAT. HE WAS KILLED.