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For chip removal and coolant filtration in many CNC machining operations, capital cost and proven efficiency still make disposable media designs the common choice. Permanent media chip removal and coolant filtration systems, however, have quickly become a viable option for helping to lower operating and maintenance costs in certain applications. In high-production operations, these systems can increase tooling life and coolant life and reduce nozzle clogging. The systems also are environmentally beneficial and provide cost savings related to media replacement and operator involvement.
Regardless of whether a shop chooses to go the route of permanent or disposable media filtration, further consideration must be given to the equipment capabilities and the requirements of the application. The Convey-R-Vac Permanent Media Vacuum Filtration System from Jorgensen Conveyors, Inc. (Mequon, Wisconsin), provides chip removal and coolant filtration down to 25 microns for CNC machine tools. According to John D’Amico, vice president of sales and marketing for Jorgensen, “The coolant is pulled through the media using a filter pump.” This suction process allows fine chips and contaminants to collect on the surface of the filter media and form a filter cake that enhances the filtering process.
“Other gravity-type drum systems require the drum to move continuously for constant cleaning to maintain coolant flow rates, since gravity is the only means of flowing the coolant through the media,” Mr. D’Amico continues. “Since there is no buildup on the drum, those systems are not as efficient in filtering the coolant. This system is unique in that it employs a vacuum and caking process.”
With Convey-R-Vac, the drum remains stationary as coolant is pulled through a suction header inside the drum. Periodically, as the cake builds on the drum during the filtration process, the drum indexes 120 degrees, allowing most of the accumulated fines and contaminants to pull away from the drum’s surface and fall to the bottom. There, fines are removed via a scraper conveyor and discharged to a scrap bin. Any fines remaining on the drum surface are removed when it indexes in front of the internal backflush spray bar.
Mr. D’Amico says his product is the first effective permanent media filtration system for difficult cast iron machining applications. “Traditionally, indexing roll media filters have been used to effectively remove cast iron fines from coolant,” he explains. “The downside of that is that you are dealing with continuous consumption of a contaminated, non-woven filter medium.”
He adds that using the filter cake to enhance the filtering process allows the system to remove particulate down to 25 microns in size. Units can be designed to include a pre-clean conveyor to handle large volumes of stringy chips and curls. Systems are sized according to the coolant flow rate of the application and can be integrated with high-pressure coolant, additional filtration and controls to provide a complete package.