Simple Solutions That Work! Issue 5

Controlling Airborne Sand The second source of airborne silica dust is sand still attached to the castings after shakeout (in pockets, cavities, and corners). As heat from the metal drives out the moisture, the loose sand falls off and contaminates downstream operations. Workers in cleaning, finishing, andmelting departments are exposed to silica dust. Dust is also generated when these “sandy” castings are shot-blasted. The sand that goes into the shot- blast systemcontributes towear on the equipment, but it also degrades and adds to the waste stream. This translates into increasing sand-dis- posal costs. The sandy returns that go back to remelt without being shotblasted, lower themelting effi- ciency and increase the volume of slag, the need for slag handling, and slag-disposal costs. Innovations in sand-casting sep- aration and cleaning have helped foundries in their determination to make their operations cleaner, and to lower operating and labor costs. These innovations have led found- ries to achieve hundreds of thou- sands of dollars in annual savings. Multi-purpose, Single Step The DIDION ® Rotary Media Drum performs shakeout, sandcondition- ing, double sand screening, casting cleaning, and casting cooling in a single efficient step. Foundries stay much cleaner because airborne silica dust declines and it offers the lowest operating cost-per-ton of any comparable package available to the global foundry community. Projects that combine these pro- cesses cut operating costs $40-80 per ton. Foundries benefit in a number of ways, including: less capital equip- ment to purchase; less floor space; much lower energy costs; less maintenance time and cost; lower shot consumption; fewer replace- ment parts; cleaner working condi- tions; and cleaner returns to remelt, which reduces slag build-up. Production is streamlinedwith cool and clean castings going directly to the finishing department. Return sand is blended and conditioned, so it is consistent in temperature andmoisture content and provides better control at amixer. Sand stays in the system where it belongs, so the foundry stays cleaner. Dust collection is highly efficient thanks to the drum’s small, open area. It requires 75% less dust col- lection than a vibrating shake- out rated at the same capacity. Counterflow air eliminates fugi- tive dust fromescaping, protecting workers from airborne silica dust. Many foundries shot-blast their castings twice: first to pre-clean the castings and returns; then, after casting grinding, to blend in the grinding marks. Since the Rotary Media Drum cleans the castings, the first shot blast step can be elim- inated. Gates, runners, and sprue are often removed so there’s no manual labor involvedand theclean returns go directly back to remelt. This shakeout system separates core sand from green sand, and discharges independently at sepa- rate points. This is popular among high-volume automotive found- ries with heavy cored work that need to meter only 15% core sand back into the green sand system. These variable-speed machines allow the foundry operators to control the action. The media bed protects nonferrous and fragile castingswhilecleaningandcooling. Custom lining configurations are available for brass, malleable gray, ductile, and steel castings. 5 BEFORE & AFTER Contact: Mark Didion markd@didion.com