See Below for Magneclutch® and Magnebrake® Engineering Calculations on the following applications:
Magnetic Particle Clutch on a Powered Rewind
Magnetic Particle Clutch for Overload Protection
Magnetic Particle Clutch for Dynamometer Testing
Quick Selection - Heat Dissipation (Slip Watts) vs. Speed Chart (RPM)
Magnetic Particle Brake on a Non-Contact Unwind
Magnetic Particle Brake for Controlled Deceleration
Selection - Heat Dissipation (Slip Watts) vs. Speed Chart (RPM)
Magnetic Particle Clutch on a Powered Rewind
| Web Force (F) | Web Speed (V) | Core Diameter (d) | Full Roll Diameter (D) | Motor Speed |
|---|---|---|---|---|
| 3.5 lbs. | 1490 fpm | 3.25 in. | 16 in. | 1750 rpm |
1. Calculate Torque
T = F x r
T Start = 3.5 lbs. x 3.25/24 ft. = 0.5 lb.-ft.
T Finish = 3.5 lbs. x 16/24 ft. = 2.3 lb.-ft.
2. Calculation Speed
N = V/πd
N Start = 1490 / π x 3.25/12ft. = 17500 rpm.
N Finish = 1490 fpm / π x 16/12 ft. = 356 rpm.
3. Calculate Slipwatts
SW = T x N Slip / 7.04
SW Start = 0
SW Finish = 2.3 lb.-ft. x (1750 - 356 rpm) / 7.04 = 455 Watts
4. From Slipwatts vs rpm curves
The 10MC90B-20 will dissipate 500 Watts at 1750 rpm.
5. Select 10MC90B-20.
Magnetic Particle Clutch for Overload Protection
| Torque Required at Conveyor (T) | Speed of Conveyor Drive Roll (N) | Motor | Gear Bpx Ratio |
|---|---|---|---|
| 20 ft. lbs. | 175 rpm | 1 hp @ 1750 rpm | 10:1. |
1. Calculate Torque at Clutch
T = T Req + Ratio
T = 20 lb.-ft. + 10 = 2.0 lb.-ft.
2. Calculation Speed at Clutch
N = N Req x Ratio
N = 175 rpm x 10 = 1750 rpm
3. Calculate Slipwatts
SW = T x N Slip / 7.04
a. In normal operation, SW = 0
b. When a jam-up occurs: SW = 2.0 x 1750 / 7.04 = 497 Watts
4. From Slipwatts vs rpm curves
The 10MC90B-20 will dissipate 500 Watts at 1750 rpm
5. Select 10MC90B-20.
Magnetic Particle Clutch for Dynamometer Testing
| Test Motor Size | Full Load Speed |
|---|---|
| 1/4 - 1 hp | 1750 rpm |
1. Calculate Torque
T = 5250 x hp./rpm
T Min = 5250 x 1/4 hp. / 1750 rpm = .75 lb.-ft.
T Max = 5250 x 1 hp. / 1750 rpm = 3 lb.-ft.
2. Calculate Slipwatts
SW = T x N slip / 7.04
SW Min = .75 lb.-ft. x 1750 rpm / 7.04 = 186 Watts
SW Max = 3 lb.-ft. x 1750 rpm / 7.04 = 746 Watts
3. From Slipwatts vs rpm curves
The 10MCA90B-20 will dissipate 785 Watts at 1750 rpm.
4. Select 10MCA90B-20.
Quick Selection - Heat Dissipation (Slip Watts) vs. Speed Chart (RPM)
Magnetic Particle Brake on a Non-Contact Unwind
| Web Force (F) | Web Speed (V) | Core Diameter (d) | Full Roll Diameter (D) |
|---|---|---|---|
| 125 lbs. | 200 fpm | 3 in. | 30 in. |
1. Calculate Torque
T = F x r
T Start = 12 lbs. x 30/24 ft. = 15 lb.-ft.
T Finish = 12 lbs. x 3/24 ft. = 1.5 lb.-ft.
2. Calculation Speed
N = V/πd
N Start = 200 / π x 30/12ft. = 25 rpm.
N Finish = 200 fpm / π x 3/12 ft. = 255 rpm.
3. Calculate Slipwatts
SW = T x N Slip / 7.04
SW Start = 15 lb.-ft. x 25 rpm / 7.04 = 53 Watts
SW Finish = 1.5 lb.-ft. x 255 rpm / 7.04 = 53 Watts
4. From Slipwatts vs rpm curves
The 25MB90S will dissipate 140 Watts at 255 rpm.
5. Select 25MB90S.
Magnetic Particle Brake for Controlled Deceleration
| Inertia of Load (WK2) | Speed of Load (N) | Time to Stop (t) |
|---|---|---|
| 1000 lb.-ft.2 | 360 rpm | 60 sec. |
1. CalculateRequired Torque
T = WK2 (rpm) / 308t
T = 1000 lb. - ft.2 (360 rpm) / 308 x 60 = 19.5 lb. - ft.
2. Calculation Speed
SW Max = T x N Max / 7.04
SW Max = 19.5 lb. - ft. x (360 rpm) / 7.04
SW Max = 966 Watts
3. Calculate Slipwatts
SW avg = √( t on / t on = t off x 1/3 x SW Max2)
SW avg = √ (1 min. / 2 min. x 1/3 x 9662)
4. From Slipwatts vs rpm curves
The 50MB90B20 will dissipate 450 Watts at 360 rpm.
