Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Page 54 of 707

Table II. Consumption Studies of Various Impacting Media Direct Pressure Dry Blasting System Average Blasting Material Glass beads (106-153 µm) Target Material Al 2024 Al 2024 CRS CRS Aluminum oxide (180 grit) Al 2024 Al 2024 CRS CRS Soda-lime silicate ground glass (125 µm and finer) Borosilicate ground glass (125 µm and finer) CRS = cold-rolled steel 3 /16-in. I.D. nozzle; 1 Al 2024 Al 2024 CRS CRS Al 2024 Al 2024 CRS CRS /8>-in. I.D. grit stem; 90o intensity; and 25 psi blasting pressure. control is achieved by maintaining that arc height peening intensity. Any change indicates some modification in the system operation, away from optimum per- formance. System control via arc height peening intensity is applicable to all cleaning, finishing, peening, and deburring operations. In cleaning, the arc height technique can be used to maintain process speed. In finishing, profilometer measure- ments of root mean square (rms) microinch finish can be correlated to peening intensity, thereby elim- inating any subjective evaluation of performance. In peening, the degree of compressive stress induced is directly related to the arc height peening intensity. By such control, significant benefits are achieved in terms of labor pro- ductivity, reduced supervision requirements, and decline in the number of rejected parts. As indicated in Table I, both steel shot and glass beads are available for peening applications. Steel shot with its heavier density offers a Hardness, Rockwell 75 B 75 B 30 C 30 C 75 B 75 B 30 C 30 C 75 B 75 B 30 C 30 C 75 B 75 B 30 C 30 C Consumption per Cycle (%) 2.1 3.5 6.0 6.7 10.6 12.9 11.4 13.9 target angle; 6-in. target distance; 0.006 Npeening Potter's Metal Finishing Glass Beads are manufactured in multiple grades using only North America Cullet. From tightly controlled products certified to meet stringent specifications like MIL PRF-9954 & AMS 2431/6, to general purpose cleaning sizes, Potters offers the most choices in beads. Our cullet is tested for heavy metals to insure worker safety and to reduce health risks associated with imported beads with highlevels of arsenic and lead. • Impart A Controlled, Clean Finish On A Variety of Metals • Clean Quickly Without Significant Metal Removal • Clean, Finish, Peen And DeBurr At Once • Can Be Recycled Many Times • Contains No Free Silica, Environmentally Safe •Meets Both Mil and AMS Specs for Heavy Metal Limits Call or e-mail anytime: 1-800-55BEADS (1-800-552-3237) Fax: 610-408-9723 Email: Potters respects the environment by recycling over one billion pounds of glass each year. 53

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