Hard Metal Grinding Filtration

Hard Metal Grinding refers to any grinding operation which involves grinding carbide or cobalt, for example in the production of tungsten carbide burrs. The main function of the grinding fluid is to remove heat and provide lubrication to the grinding process. Grinding fluid also flushes grinding fines and debris from the grinding zone. Therefore good hard metal grinding filtration is important to ensue no hard metal grinding fines are returned to the grinding process.

For maximum cooling water-based grinding fluids are preferred but often neat oil is used. Neat oil has inferior heat removing capacity compared to water-based coolant therefore external chillers are often used to provide extra cooling.

Water based emulsions leach and dissolve carbide into the fluid. The resulting health issues can be severe. Operators can develop skin related problems. The inhalation of mist from the grinding process is another health hazard. Cobalt build up in the fluid leaves sticky deposits on the machine tool beds producing an uninviting and difficult working environment.

Additionally, grinding fines can be sub 5µ which make them difficult to remove. Eventually they fall to the bottom of the grinding machine coolant tank producing sludge and causing frequent sump clean outs. It is therefore vital that cobalt fines are removed from both water-based coolants and neat oils as quickly as possible. Centralised filtration systems offer real benefits in hard metal grinding as fines are efficiently removed before they can contaminate the process.

Hard Metal Grinding Filtration

Working Principle of The Vivex Decantor System

There is no need for any filtration equipment or sump tanks at the grinding machine. These are replaced with a self-cleaning vortex tank to collect contaminated coolant and return it through a pipework system to the central Decantor unit. Two separate lamella chambers operate in the Decantor system, the first in continuous flow separating course particles. The other is periodically motionless to settle out fine particulate which otherwise would continually circulate. In this way clean fluid is supplied to the grinding machines.

The separated particles settle on the lamella plates and are collected by scraper to be discharged to a dewatering unit for recycling. Alternatively, a sludge barrel system is used which allows particulate to be collected and capped off ready for recycling.

Any fluid losses in the system from evaporation or drag out is made up by the automatic topping up system so that coolant levels remain constant. Virtually maintenance free the Decantor lamella packages have a self-cleaning system operated once a day by compressed air.