Document om44Y76Kqr04YeGLwLmxzbEpr

-45- Dust partioles in samples taken during the operation of Universal grinders have these characteristics (Continued)? Material Being Size of Ground Wheel Hardened Car bonated Steel (Pipe Grip for Pipe Machine) 1/2" x 5" Type of Wheel Alundum (3846 J 5B) Case Hardened Steel (Plung ers for Fill ing Machine) 2" x 3-1/2" Aloxite (Grit 401-P25 Type 12) Characteristics of Dust Particles. (Sizes and Percentages Estimated) About 30# angular crystalline, about 2 microns or less in size; 70# round black opaque, less than 1 micron in size. Numerous black specks too small to count. Several large oblong black opaque par ticles about 20 microns wide and 35 or 40 microns long. All particles black opaque, 1 mi cron or less in size. E - SURFACE GRINDERS? Surface grinders are used almost exclusively on valves and dies. They are equipped with either l/2" x 8" Horton Alundum (1946H) wheels or l/2" x 4" to 6" Carborundum (Aloxite) wheels. Ho dust collectors are provided, the dust being thrown out into the atmosphere. Samples taken during the operation of surface grinders had the following dust concentration (10 microns or less)? Operatlon Particles per cu. ft. Grinding Soft Cast Steel Valve on l/2" x 6" Carborundum Aloxite Wheel...................................................... " Tool Steel Die on l/2" x 8" Alundum (1946H) Wheel..................................... Dressing Surface of l/2" x 8" Alundum Wheel with a "Diamond Point"...................................................................... 566,400 1,019,520 1,132,800 About 70# of the particles from grinding the steel die were metallic, 3 mi crons or less, whereas 98# of the particles from grinding the soft steel valve were metallic. Many of the particles were too small to identify or count accurately, F - LAHDIS TOOL GRINDERS? Landis tool grinders are usually equipped with two different types of .wheels, one for side grinding and the other the ordinary type, 1-1/2" x 12" Carborundum Aloxite (Grit 40, Grade H, Bond 33) is used for general purpose grinding suoh as bull chisels, diamond points, cold chisels, flanges and scrappers. The Side Grinding Type is usually a 2-l/2" x l-l/2" x 12" Grit 46A-P P678 Aloxite brand AA wheel used for grinding Landis dies. At one plant the wheels of the Landis tool grinder are enclosed by hoods at the rear of each of which is attached a two-inoh pipe connected to a three-inoh pipe which discharges into a sewer. Suction is induced by a stream of compressed air from a half-inch pipe in serted in the two-inch pipe just back of the hand. This arrangement acts as a sy phon and pulls the dust away from the person using the grinder. Samples taken dur ing the operation of-Landis tool grinders had dust concentrations as followst E HO 0153 5