Abrasive substances play havoc with pumping equipment used to deliver coolant to the cutting head on lathes that machine quartz glass for television tubes.
Glass particles in the coolant can wear out the bearings on the pump shaft, which spins at 3,000rpm, ‘in five minutes flat’ says Geoff Maxted, sales engineer with Albany Engineering.
Albany, the UK’s biggest producer of gear pumps, solved the problem for special machine tool maker Heathway with a pumped coolant system that eliminates contact between the pump’s wetted parts.
The pump is semi-submerged in a tank that had to be small enough to fit inside the machine tool. Albany devised a system of baffles and weirs to lengthen the fluid path within the tank, increasing the opportunity for basket strainers to remove particles.
In case any particles still get through, the pump, a verticle centrifugal or suds pump, has also been modified to eliminate the bearing that supports the impeller in the coolant.
Instead of a parallel-sided shaft connecting the motor to the impeller, Albany designed a less flexible tapered shaft which needs no bearing, thus eliminating the moving contact between wetted parts.