Renewing A Precious Resource,
American Machinist, October 1999
(in Technology Trends section)
The Waterjet Abrasive Recycling Dispenser, called WARD 24, removes sludge from waterjet tanks and recycles as much as 50% for reuse. Developed by EasiJet, the device promises not only to slash costs by reusing waterjet abrasive and eliminating disposal costs but also to decrease the downtime caused by tank cleaning.
In waterjet cutting, thousands of minuscule, glassy mineral particles, typically garnet, and highly pressurized gallons of water are forced out of an opening no larger than a human hair. A typical waterjet system, for instance, can use as much as 2 kg/min of garnet. At a cost of roughly $0.35/lb, a company could easily spend thousands of dollars a month on abrasive alone.
After a machine finishes cutting, the abrasive and fines from the workpiece fall into a large water tank, creating a sludge that must be emptied at regular intervals.
The WARD 24 employs a series of patented nozzles, all switched on automatically, to suction the sludge to the unit, where it is washed and passed through several screens. Smaller, unrecyclable garnet and fines from the cut metal fall through the primary screen. The larger, reusable particles are then passed into the dryer, through a secondary screen and into a hopper for reuse. Sometimes this abrasive cuts faster than the new abrasive, reports EasiJet, because there is a lower percentage of contaminants as well as new jagged edges on some particles.
During the washings, water from the waterjet tank is used, with only 1.9 to 3.8 liter/min of fresh water needed for a final rinse. All water is returned to the tank. The recycled abrasive can then be reused immediately or mixed with a new abrasive, depending on the cutting need.
The WARD is distributed by WARDJet, Tallmadge, Ohio. Information on the machine can be found at www.wardjet.com.
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