How to use the speed table
The number of revolutions per minute (n, min⁻¹) is determined by two parameters:
- D— outer diameter of the abrasive wheel (mm)
- V s— maximum operating speed (m/s) indicated on the wheel marking
To find the allowable RPM, find the diameter of your wheel in the left column of the table, then move right to the column with the desired maximum speed. The number at the intersection is the maximum allowable spindle RPM for that wheel.
Example: A circle with a diameter of 125 mm marked V s = 80 m/s → permissible speed 12,200 rpm. The tool must operate at a speed not higher than this value.
Formula for calculating the speed of the abrasive wheel
Relationship between peripheral speed, diameter and number of revolutions:
also:
- n— number of revolutions per minute (rpm)
- V s— maximum operating speed (m/s)
- pi— 3.14159
- D— outer diameter of the circle (mm)
The inverse formula for checking the peripheral speed of your tool is:
This formula allows you to check whether the actual spindle speed does not exceed the maximum permissible for a particular wheel.
Recommended RPM table
Revolutions per minute (n, min⁻¹) depending on the outer diameter D and the maximum operating speed V s. The values are rounded according to industry practice.
| D, mm | 16 | 20 | 25 | 32 | 35 | 40 | 50 | 63 | 80 | 100 | 125 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Maximum operating speed V s, m/s | |||||||||||
| 4 | 75 300 | 95 400 | — | — | — | — | — | — | — | — | — |
| 5 | 61 100 | 76 300 | 95 400 | — | — | — | — | — | — | — | — |
| 6 | 50 900 | 63 600 | 79 500 | — | — | — | — | — | — | — | — |
| 8 | 38 100 | 47 700 | 59 600 | 76 300 | 83 500 | 95 400 | — | — | — | — | — |
| 10 | 30 500 | 38 100 | 47 700 | 61 100 | 66 800 | 76 300 | 95 400 | — | — | — | — |
| 13 | 23 500 | 29 300 | 36 700 | 47 000 | 51 400 | 58 700 | 73 400 | 92 500 | — | — | — |
| 16 | 19 000 | 23 800 | 29 800 | 38 100 | 41 700 | 47 700 | 59 600 | 75 200 | 95 400 | — | — |
| 20 | 15 200 | 19 000 | 23 800 | 30 500 | 33 400 | 38 100 | 47 700 | 60 100 | 76 300 | 95 400 | — |
| 25 | 12 200 | 15 200 | 19 000 | 24 400 | 26 700 | 30 500 | 38 100 | 48 100 | 61 100 | 76 300 | 95 400 |
| 32 | 9 540 | 11 900 | 14 900 | 19 000 | 20 800 | 23 800 | 29 800 | 37 600 | 47 700 | 59 600 | 74 600 |
| 40 | 7 630 | 9 540 | 11 900 | 15 200 | 16 700 | 19 000 | 23 800 | 30 000 | 38 100 | 47 700 | 59 600 |
| 50 | 6 110 | 7 630 | 9 540 | 12 200 | 13 300 | 15 200 | 19 000 | 24 000 | 30 500 | 38 100 | 47 700 |
| 63 | 4 850 | 6 060 | 7 570 | 9 700 | 10 600 | 12 100 | 15 100 | 19 000 | 24 200 | 30 300 | 37 800 |
| 80 | 3 810 | 4 770 | 5 960 | 7 630 | 8 350 | 9 540 | 11 900 | 15 000 | 19 000 | 23 800 | 29 800 |
| 100 | 3 050 | 3 810 | 4 770 | 6 110 | 6 680 | 7 630 | 9 540 | 12 000 | 15 200 | 19 000 | 23 800 |
| 115 | 2 650 | 3 320 | 4 150 | 5 310 | 5 810 | 6 640 | 8 300 | 10 400 | 13 200 | 16 600 | 20 700 |
| 125 | 2 440 | 3 050 | 3 810 | 4 880 | 5 340 | 6 110 | 7 630 | 9 620 | 12 200 | 15 200 | 19 000 |
| 150 | 2 030 | 2 540 | 3 180 | 4 070 | 4 450 | 5 090 | 6 360 | 8 020 | 10 100 | 12 700 | 15 900 |
| 175 | 1 740 | 2 180 | 2 720 | 3 490 | 3 810 | 4 360 | 5 450 | 6 870 | 8 730 | 10 900 | 13 600 |
| 180 | 1 690 | 2 120 | 2 650 | 3 390 | 3 710 | 4 240 | 5 300 | 6 680 | 8 480 | 10 600 | 13 200 |
| 200 | 1 520 | 1 900 | 2 380 | 3 050 | 3 340 | 3 810 | 4 770 | 6 010 | 7 630 | 9 540 | 11 900 |
| 230 | 1 320 | 1 660 | 2 070 | 2 650 | 2 900 | 3 320 | 4 150 | 5 230 | 6 640 | 8 300 | 10 300 |
| 250 | 1 220 | 1 520 | 1 900 | 2 440 | 2 670 | 3 050 | 3 810 | 4 810 | 6 110 | 7 630 | 9 540 |
| 300 | 1 010 | 1 270 | 1 590 | 2 030 | 2 220 | 2 540 | 3 180 | 4 010 | 5 090 | 6 360 | 7 950 |
| 350 | 870 | 1 090 | 1 360 | 1 740 | 1 900 | 2 180 | 2 720 | 3 430 | 4 360 | 5 450 | 6 820 |
| 400 | 760 | 950 | 1 190 | 1 520 | 1 670 | 1 900 | 2 380 | 3 000 | 3 810 | 4 770 | 5 960 |
| 500 | 610 | 760 | 950 | 1 220 | 1 330 | 1 520 | 1 900 | 2 400 | 3 050 | 3 810 | 4 770 |
| 600 | 500 | 630 | 790 | 1 010 | 1 110 | 1 270 | 1 590 | 2 000 | 2 540 | 3 180 | 3 970 |
| 750 | 400 | 500 | 630 | 810 | 890 | 1 010 | 1 270 | 1 600 | 2 030 | 2 540 | 3 180 |
| 800 | 380 | 470 | 590 | 760 | 830 | 950 | 1 190 | 1 500 | 1 900 | 2 380 | 2 980 |
| 1 000 | 300 | 380 | 470 | 610 | 660 | 760 | 950 | 1 200 | 1 520 | 1 900 | 2 380 |
| 1 250 | 250 | 310 | 390 | 500 | 550 | 630 | 790 | 1 000 | 1 270 | 1 590 | 1 980 |
| 1 500 | 200 | 250 | 310 | 400 | 440 | 500 | 630 | 800 | 1 010 | 1 270 | 1 590 |
Lines are highlighted for the most common diameters: 115, 125, 150, 180, 230 mm (grinders) and 300, 350, 400 mm (stationary machines).
Typical operating speeds of abrasive wheels
The maximum operating speed V s depends on the type of tool and purpose:
| Type of abrasive tool | V s, m/s | Note |
|---|---|---|
| Cutting and grinding wheels (bakelite bond) | 80 | Standard EN 12413; some for machine tools - 100 m/s |
| Flap discs | 80 | Types 27 and 29 for Bulgarians |
| Grinding wheels (ceramic bond) | 20–50 | Depending on the design and grain size |
| Diamond wheels (metal bond) | 16–32 | Stationary equipment |
| Diamond wheels (polymer bond) | up to 50 | Finishing sanding |
| CBN and electroplated | 80–125 | High-performance grinding |
Practical calculation examples
Example 1: Cutting wheel 125 × 1.0 mm for grinder
D = 125 mm, V s = 80 m/s.
A standard 125 mm grinder operates at 11,000–12,000 rpm — a compatible value.
Example 2: Grinding wheel 230 × 6.0 mm
D = 230 mm, V s = 80 m/s.
A standard 230 mm grinder operates at 6,500 rpm - it meets the requirements.
Example 3: Circle for stationary machine 300 × 32 mm
D = 300 mm, V s = 35 m/s.
Before installation, make sure that the machine is operating at a speed lower than 2,220 rpm.
Safety rules regarding rotation speed
Check the labeling
Each wheel certified to EN 12413 has a maximum speed (m/s) and corresponding revolutions (RPM) on the label. These values are determined by the manufacturer based on tensile tests at 1.5 times the operating speed.
Do not modify the tool.
It is forbidden to remove the rev limiter or use the speed controller to increase the revs above the nominal value. It is also forbidden to install a wheel of a different diameter without checking compatibility.
Consider wear and tear
During operation, the diameter of the wheel decreases - the peripheral speed at the same speed decreases. This is safe. But when replacing a worn wheel with a new one , be sure to check the correspondence of the speed to the new diameter.
Why it's important to stick to the recommended speed
The abrasive wheel rotates at extremely high speed. When the maximum speed is exceeded, centrifugal forces increase in proportion to the square of the speed: doubling the speed increases the load on the wheel by a factor of four.
The destruction of the wheel at operating speed leads to the scattering of fragments with kinetic energy sufficient to cause fatal injuries. Even a protective cover does not guarantee complete protection if the speed is significantly exceeded.
That is why the European standard EN 12413 requires a tensile test at 1.5 times the maximum operating speed. This standard provides a safety margin - but only if the specified speed is maintained.
Frequently asked questions
The revolutions are always indicated on the wheel label. They can also be found in the table - at the intersection of the row with the diameter and the column with the speed V s. The formula for calculating: n = (V s × 60,000) / (π × D).
Centrifugal forces will destroy the wheel. Fragments fly at speeds of up to 80 m/s and can cause serious injury or death. In addition, the wheel may lose stability, start to vibrate and break free from the tool.
Yes, but on the safe side. When the diameter decreases due to wear, the peripheral speed at the same speed decreases - a worn wheel works with a greater margin of safety. When replacing with a new one, be sure to check the correspondence of the speed.
Velocity in m/s is the linear velocity of a point on the edge of the circle. RPM is the number of complete revolutions per minute. They are related by diameter: the larger the diameter, the fewer revolutions are required for the same peripheral velocity.
A standard 125 mm cutting wheel at V s = 80 m/s has a permissible speed of up to 12,200 rpm. Grinders for 125 mm wheels usually operate at 11,000–12,000 rpm - this is compatible.
A 230 mm circle at V s = 80 m/s is designed for a maximum of 6,640 rpm. Standard 230 mm grinders operate at 6,500 rpm.
The 100 m/s wheels have a reinforced design and allow higher speeds. For the 125 mm wheel: at 80 m/s — max. 12,200 rpm, at 100 m/s — max. 15,280 rpm. The 100 m/s wheels are suitable for high-speed tools and provide an additional margin of safety.
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