The modern world would be inconceivable without flat glass – most of us will come into daily contact with it from windows to furniture or mirrors in the home. Flat glass also plays an important part in architecture and various fields of technology, where safety glass or photovoltaics are a critical necessity in manufacturing, testing and production facilitates.
Saint-Gobain is a market leader in the production of flat glass, high performance materials and construction products. In fact every car in Europe is fitted with glass from Saint-Gobain. Due to the diversity in the applications Saint-Gobain caters for and our commitment to quality, standards and environmental protection, we also realise that the methods applied when processing flat glass is just as critical as the initial manufacturing stages to ensure quality, safety and efficiency.
Flat glass processing
Flat glass is cut to the appropriate sizes (in fact it is scribed and broken with controlled force or cut with diamond cut-off wheels) and the resulting edge is extremely sharp and can only remain in its original state if it is framed.
In all other instances, the edges are finished by grinding with diamond tools and polishing with conventional abrasives and polishing agents. This process is often a balance of achieving the very best grinding results and maintaining optimum processing speeds, but is also impacted by the type of edge and finish that is required.
At Saint-Gobain, our main objective is to offer innovative solutions to address the challenges our customers come face-to-face with, by adopting optimised high-performance grinding tools that are perfectly tailored to specific needs and requirements.
The Norton WINTER brand from Saint-Gobain
Norton WINTER is renowned for high-quality diamond and cBN grinding tools for industrial production and has served the flat glass processing market for over 160 years.
The Norton WINTER range is not limited to standard grinding tools: more than 75% of applications involve customised solutions, which have been developed in close cooperation with the end-user. This successful engineering approach is based on a modular performance package, individually adapted according to specific requirements of the customer.
Optimisation for glass edge processing on linear machines
Apart from the machine settings for process improvement, such as the infeed rate for the individual stations (allocation of cut), feed rate and set angle of the grinding wheels – huge improvements can be achieved by optimising the design of the grinding wheels, the geometry and design of the abrasive layer, the grit size, concentration and the type and variation of bond. By aligning abrasive tool selection and optimisation with process improvement, the overall processing time can be reduced, which will in turn help to free-up capacity, reduce processing costs and improve the quality and finish of the end product. This also helps to reduce scrappage and material waste, which is better for the environment as well as the profit margins for the business.
Choosing the correct geometry and design of the abrasive layer
Segmented Grinding Wheels
Segmented grinding wheels are required for processing laminated safety glass. The segmentation enables the resin-layers to be cut, which compared to glass, is soft and tough. Cooling and chip removal for glass with a thickness greater than 10mm will also benefit from rim segmentation.
Peripheral Grinding Wheels
In order to produce the correct edge on a sheet of glass with a peripheral grinding wheel, it is important to ensure the geometry of the abrasive layer matches the finished edge of the glass. This is achieved by creating an inverse image of the glass edge, which is then profiled onto abrasive layer of the grinding wheel.
Cup Wheels
By contrast, cup wheels optimally distribute the grinding stresses across the full width of the abrasive coating when forming radii and mitres. Customised tool designs allow the removal rate and the grinding result to be further optimised according to individual grinding processes
Choosing the correct grit and concentration
Removal rate and surface quality are determined by grit size. Coarse grit enables a high removal rate whereas fine grit creates a smoother surface.
It is important to note though that thick glass and high infeed rates demand coarser grits during the grinding process; however when processing thin glass, chipping can be avoided by choosing finer grit sizes.
When processing glass, the diamond concentration is typically between C25 and C40. Lower concentrations in grinding wheels are generally freer cutting and are more versatile, so are often used in a wider range of applications, while tools with a high concentration of abrasive material ensure a long service life and high removal rates.
Types and variations of bond
Due to their resistance to wear and excellent grit retention, metal bonds are particularly suited for grinding glass. Resin bonds are sometimes used on the final grinding stations; despite the slightly higher wear rate, they are characterised by a very fine and soft finish. Thin glass or extra fine surfaces can be reliably processed in this way.
Both metal and resin bonds are available in different variations. The grinding behaviour of different wheel specifications is strongly influenced by the bond properties - optimum results are obtained by selection of the most suitable bond and microstructure.
Service and support with processing optimisation
Choosing the correct abrasive for linear machine processing may seem like a complicated and lengthy affair. Without the right expertise and guidance, the process of abrasive optimisation could become a series of trial and error that could generate the opposite results to what is required.
Saint-Gobain works closely with customers to understand their processing methods and requirements. Saint-Gobain not only provides high performance Norton WINTER grinding tools but our field service engineers and customer service team also assist in analysing your processes to identify the best solution and then implement it with you.
At our EGTC (European Grinding Technology Centre), we can evaluate your grinding processes using sophisticated sensing and measurement systems so we can demonstrate improvements to your process without interrupting your production. Our dedicated specialists are expert in the field of complex grinding systems and can advise on new production strategies with the help of innovative process diagnostic technology. The results for our customers are fine-tuned production process and optimised day-to-day operations.
Speak to one of our experts today to see how your production methods can be further optimised to help you save time, money and resources.
Training and continuing education
We offer regular seminars on current issues and developments at our European Grinding Technology Centre (EGTC) in Germany. Economic and advanced production processes are reviewed with top-class experts from different parts of industry. We invite internal and external consultants on specific subjects to comment on the technological state-of-the-art and development trends. Specific training programmes can also be arranged according to your individual requirements. Just contact us - we will gladly make an offer that meets your needs and optimise your production process.
For more information contact your local sales rep or contact us here.