Norton Vitrium3 bond is a breakthough grinding wheel technology with multiple benmefits

The task of the bond matrix is to hold in place the abrasive grains, which can be of various types, from the proprietary Norton Quantum ceramic to conventional aluminium oxide. The secret of a good bond is that the particles of vitrified clay or glass employed impact the grinding process as little as possible. Saint-Gobain Abrasives' R&D division spent three years developing and optimising the Vitrium3 bond, applying for patents and bringing it to market. As a world-leading glass manufacturer, the company's parent group has considerable technological experience in vitrification technology, which was key to discovering the novel chemistry behind the formulation of the bond. While extremely porous, Vitrium3 is the company's toughest bond to date, adhering strongly to the grains. It allows the grinding wheels to be light and, hence, used safely at speeds up to 80 m/sec, even though there is only a small amount of bond material retaining the abrasive. Higher feed rates, spindle speeds and infeed may be employed, significantly increasing productivity. In addition to raising machining efficiency, the strong bond increases the life of Vitrium3 wheels by up to 30%, compared with conventional bonds. Despite the low bond-to-abrasive ratio, grain adhesion and holding power are superior to those of any other bond. Wheel form retention and radius accuracy are significantly improved, reducing dressing time and so minimising wear on the diamond dresser and wheel, increasing the service life of both. The grinding wheel structure increases exposure of the abrasive grains and improves coolant flow. The wheel is therefore able to discharge swarf more efficiently and grind at a higher metal removal rate. Q' is typically 20% higher than when using wheels made with a conventional bond. Greater exposure of the grain to the component being machined reduces grinding forces by up to 25%. The power drawn from a machine is lowered by typically 15%, saving energy, and workpiece deflection is reduced, leading to better machining accuracy. These characteristics also permit less rigid and lower power grinding machines to deliver better results. Grinding pressures and energy consumption are further reduced by decreased interaction between the bond and the component, a consequence of thinner bond posts holding the abrasive grains. An additional advantage is that free flow of coolant through the porous matrix results in efficient chip clearance, avoiding wheel loading and clogging. Grinding burn is practically eliminated, and so too are residual stresses and metallurgical change in the surface of the component. This is especially important in aerospace applications, such as when jet engine vanes and turbine blades are being ground from nickel-based superalloys. It is also critical for machining other heat sensitive materials such as tool steels and chromium molybdenum. Creep-feed as well as traditional grinding practices are supported. Applications include cylindrical grinding of automotive crankshafts and camshafts; gear grinding; surface grinding of linear bearings and mould tools; internal grinding of hydraulic components, bearing tracks and gear bores; and centreless grinding of bearing race ODs (outside diameters), bar and tube. Vitrium3 benegfits hold true irrespective of the grain and wheel type, be it straight, cylindrical, cup or segmented. Each abrasive has distinct hardness, strength, fracture toughness and impact resistance properties, suitable for different applications. In some of Saint-Gobain Abrasives' more highly engineered grinding wheels, two or more grain types are often combined to achieve specific operational characteristics. David Balshaw, business development manager - Engineered Markets at Saint-Gobain Abrasives, advised: "Whether the goal is to reduce total cost per part, increase throughput, or improve workpiece quality, Norton Vitrium3 is reshaping the world of precision grinding to meet these needs. "We offer an exclusive Process Solutions Programme (PSP) free to customers, during which a trained engineer visits the user's site to analyse their grinding operations and make enhancements to increase productivity, improve quality, reduce costs and improve safety. "With the introduction of the Vitrium3 bond, it is highly likely that our new grinding wheels will feature prominently in future optimisation programmes to reduce customers' unit manufacturing costs."