Andor abrasives: Optimum bonding systems with Grinding Techniques

Bonding systems play a critical role in the performance of precision abrasives and can be seen as the “glue” that keeps everything together.

A high-quality bonding system holds the grain in place up to the optimum point where the grain is held just long enough for it to get blunt, and then to release the dull grain, in order to expose new sharp grains to continue with the cutting operation. A poor bonding system, however will release grain too early during operation which is also known as premature grain shedding, however where a bonding system holds the grain in place for too long, it will start glazing and eventually burn the material, resulting in an increase in dressing cycles between grinding operations, leading to a rise in lost time and inventory on grinding media.

Vitrified wheels

Two of the most popular bond systems, the Vitrified and Resinoid products, can be distinguished with the letter V for Vitrified, and the letter B, for Resinoid as part of the product specification. With both bonds being equally suitable for various applications, each one has certain characteristics that sets it apart from the other.

A vitrified bond is constructed from different types of clay and grains and are fired in a kiln at temperatures typically above 1250 degree Celsius. During this firing operation the clay or feldspar bonds with the grains around it. During the cooling process, each grain is surrounded by a glass like material which strengthens the bond and adds to the wheel’s overall rigidness. With these characteristics a Vitrified precision bonded wheel is perfect for applications requiring high stock removal where precision tolerances are required.

Vitrified application

These wheels are often referred to as glass like in nature, as they are not able to handle any shocks or blows, compared to a Resin bonded wheel which are more rigid and resistant to shocks or blows.
Although not as rigid, Vitrified bonded wheels can be stored indefinitely, as they are not affected by water, or variations in temperature, while Resin bonded wheels are affected by alkali, humidity, and extreme weather conditions, resulting in deterioration of the bond over time.

Resin bonded systems are constructed from Phenolic resins and different types of fillers which gives it its characteristics. It is cured in ovens between 150 to 200 degrees Celsius, making it tougher but less rigid than a Vitrified bond, and suitable for precision grinding applications running at high speeds, necessitating high stock removal.

Resin wheels

While Vitrified bonds break away under pressure during application, Resin bonds require heat to break away. In some cases, when insufficient pressure is applied during operation, Vitrified bonds will clog, as the bond cannot break away to expose new sharp grain at the optimum point on application. This can easily be rectified by increasing the pressure or infeed rate during the grinding operation.

When Resin bonded precision wheels are exposed to too much heat during operation, the bond system will break away too rapidly at the point of contact. To rectify this, coolant can be increased to keep both the workpiece and grinding wheel as cool as possible. It is of utmost importance to maintain any coolant when the acidity level creeps up, as a too high acidity level will attack the bonding system, causing it to break away prematurely. Cleaning out the whole coolant system and replacing it with a mixture at the correct percentages will alleviate this during application.

Resin wheel application

To ensure precision grinding applications are served with the best in bonding systems, it is important to partner with a supplier that understands these factors. Grinding Techniques have been locally manufacturing Andor precision abrasives for over 40 years.

For further information contact Grinding Techniques on TEL: 011 271 6400 or email or visit