The machine raises the wheel speed to maintain the surface speed as a wheel wears, but it is unusual that the machine also changes the dresser speed to maintain how we dress the wheel. Usually this means that the wheel will need changing every few hundred meters.
As the diameter of the wheel decreases, so does the length of each pass required to cover the same distance. This means that for a given rate of wear, you will need to change the wheel more frequently as it wears down.
Also as the diameter of the wheel decreases, so does its weight. This means that it will take more passes to lift the same amount of material off the dresser. For example, if you were dressing one pound blocks with a two inch diameter wheel, you would need a four inch dresser to lift the same amount of material at half speed.
Finally, as the diameter of the wheel decreases, so does its efficiency. This means that you will need more passes to lift the same amount of material—or in other words, you will need to change the wheel more often as it wears down.
In conclusion, as a grinding wheel wears, you will need to change it more often than not because less material will be lifted with each pass.
Purpose. The goal of dressing the wheel is to correct it by knocking abrasive particles off the surface and making the wheel concentric. This reduces vibration and enhances surface smoothness by removing the vibration caused by the out-of-balance wheel over the surface of the workpiece.
There are two types of dressings: manual and automatic. With either type of dressing, very small balls or pebbles are used to remove material from the face of the wheel. These balls or pebbles are called "dressing stones". There are three ways that material can be removed from the wheel: by scratching, by rubbing, and by blasting. Scratching is done with sharp tools such as files or needles. Rubbing is done with softer tools such as sandpaper or cork blocks. Blasting is done with water or air under pressure.
Manual dressers use several stones with different shapes for scratching off material. These stones are held in a stone holder so they do not get damaged during usage. The wheel is rotated while the dresser is moved across its face. Automatic dressers use sensors to detect where on the wheel there is most wear and replace the dressing accordingly.
Dressings can be applied to flat or profiled wheels. For profiling wheels, special tools are needed to achieve a finished look.
The purpose of dressing is to make grinding wheels smooth and even.
The speed in the statistics below is measured in surface feet per minute rather than revolutions per minute. The length of the path the abrasive grit travels as it circles around the wheel axis determines the actual speed of the abrasive grit on the wheel perimeter. The faster the surface speed at a given rpm, the bigger the wheels. Generally, speed ratings are published for stones that have been tested to determine their durability. These ratings usually include a maximum permissible surface speed in meters per second (m/s) or miles per hour (mph). A stone that has been rated at 10,000 m/s will not last very long if used at home-made grinding speeds of just a few hundred m/s.
Grinding wheels were originally made from solid pieces of hard material such as diamond or cubic boron nitride (CBN). Today's grinding wheels are mostly made from sintered metal powders with some ceramic additives. No matter what type of wheel is used, the longevity of the tool depends on how fast it is turned. Grinding speed affects the wear rate of the wheel, and thus its life. Reducing the speed of the wheel can prolong its life but this comes at the cost of reduced grinding efficiency. Turning the wheel too slowly also puts stress on the bearing system and may cause it to fail prematurely.
There are two types of bearings used in grinding wheels: ball bearings and roller bearings. Roller bearings spread the load over a large area which reduces the pressure on any one point.