Choosing Blast Media S780 S660 S550 S460 S390


Many different types of blast materials exist, but which ones are an exact fi t for your facility and product mix?


Shea Gibbs, Senior Editor


operations—a conveyor vibratory sys- tem for large volumes and a tub system for smaller runs. It also has a standard shotblast machine using metallic media to produce a matte fi nish. And then there is a fourth option. “It’s a cement mixer,” said company


P


Table 1. Available Shot and Grit Sizes Shot


SAE Size No. S780 S660 S550 S460 S390 S330 S280 S230 S170 S110 S70


34


Nominal Size (in.) 0.0787 0.0661 0.0555 0.0469 0.0394 0.0331 0.0278 0.0234 0.0165 0.0117 0.007


SAE Size No. G10 G12 G14 G16 G18 G25 G40 G50 G80


G120


rima Die Casting Inc., Clear- water, Fla., uses several dif- ferent shot blast techniques in its plant. The company uses ceramic media in two different


Vice President/General Manager Arne Swanson while pointing at a small ap- paratus in the corner of the facility’s fi nishing room. “It’s nothing fancy, but it gets the job done.” Swanson’s comment could be a


tag line for the shot blasting market as a whole. The materials used in the process are rarely complex, but getting the job done is the name of the game. “You want to use the smallest [mate- rial] that still does the work,” said Bill


Rhodaberger, vice president of sales for blast media maker Ervin Industries, Ann Arbor, Mich.


The Long View The market for blast materials com-


Grit


Nominal Size (in.) 0.0787 0.0661 0.0555 0.0469 0.0394 0.0278 0.0165 0.0117 0.007


0.0049


monly used in the metalcasting industry can be broken down in several ways— reusable vs. expendable media, metallic vs. non-metallic media, shot vs. grit. The most commonly used material in metal- casting facilities (about 98%, according to Rhodaberger) is reusable steel shot or grit. Shot by far outpaces grit. The other 2% of the industry includes non- metallic materials such as glass beads, plastics or the ceramics employed by Prima Die Casting. The 98% majority can include car-


bon steel and stainless steel products, with stainless being used in applica- tions that cannot be imparted with ferrous residue. “Steel shot or grit may leave a micro-


scopic ferrous residue,” Rhodaberger said. “If you are making aluminum wheels, for example, stainless shot can be used to avoid rusting.” The three major producers of shot


MODERN CASTING / January 2011


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