Speed, pressure, bond hardness and technique decide how fast a bonded abrasive cuts and how long it lasts. Get them right and you get the most out of every disc.
Speed
Too low
If the machine runs at too low an RPM, cutting-off wheels and grinding discs tend to “jump” and the disc edges wear unevenly. On thin cross-sections, such as tin or wire, the grit breaks away from the bond and the disc wears faster than normal.
Optimal
Klingspor cutting-off wheels and grinding discs are high-performance products. They give their best stock-removal-to-wear ratio just below the maximum peripheral speed. Keep the machine running at a consistently high RPM. If it can’t hold speed, use a more powerful machine.
Too high
The maximum RPM and peripheral speed are printed on the label of every disc. For your own safety, never exceed them.
Grinding pressure
A clean cut needs the right grinding pressure. A common mistake is easing off to save the disc and make the wheel last longer. The material then overheats (turns blue), and the cutting-off wheel clogs and “burns up”. Always apply enough pressure to keep the cutting time as short as possible, especially on heat-sensitive materials with large cross-sections.
Choosing the right hardness
Cutting-off wheels
The rule of thumb for cutting-off wheels: the harder the material, the softer the bond. A cutting-off wheel’s service life depends on whether the cut surface of the workpiece hardens. Overheating makes the disc “glaze”, and it stops cutting well. When that happens, switch to a softer cutting-off wheel.
Grinding discs
The same rule applies to grinding discs: the harder the material, the softer the bond. The application matters just as much. Corner grinding and grinding burrs or sharp edges can tear grit out of the bond, so use a hard bond for that work. On surfaces and small weld seams, a disc that is too hard goes dull. It lasts a long time but removes little stock, which pushes up labour costs. Use a medium or soft bond for finish grinding.
Cutting-off technique
Apply pressure to a cutting-off wheel in the radial direction only. It is the only way to avoid wobbling, buckling and disc breakage, especially under high cutting pressure. Clamp the workpiece firmly to the bench so the disc can’t slide off to the side. Clamp it as close to the cut as possible so it doesn’t vibrate, flutter or slip.
Grinding technique
Hold the grinding disc at about 35 degrees to the workpiece. This angle gives the intended stock-removal-to-wear ratio. Below 15°, a very thin, flattening edge forms around the circumference of the disc. Even a small change in angle can then leave the disc unable to take the grinding pressure, and it slips to the side. Good grit goes unused and the disc runs out of balance, so it has to be replaced early.
Mounting for power transmission
Cutting-off wheels and grinding discs are mounted on the machine with side flanges, which transfer the power to the disc. For safety, never use defective or incorrect flanges.
Mounting for safety
Wheel flange FL 76 gives more lateral stability and control, particularly with thin, flat cutting-off wheels of 180 mm and 230 mm diameter.
Follow the applicable regulations and standards when using the wheel flange. The contact surface and diameter of the wheel flange must match. Never use wheel flanges with mismatched diameters.
