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)
T = Force x Radius
T Start = 3.5 lbs. x 3.25in./24in. = 0.5 lb. ft.
T Finish = 3.5 lbs. x 16in/24in. = 2.3 lb. ft.
2. Calculate Speed (RPM)
RPM = Velocity/π(diameter)
RPM Start = 1490 fpm / π x 3.25in/12in. = 1750 rpm
PRM Finish = 1490 fpm / π x 16in./12in. = 356 rpm
3. Calculate Slipwatts (SW)
SW = T x (RPM in - RPM out) / 7.04
SW Start = 0
SW Finish = 2.3 lb. ft. x (1750 rpm - 356 rpm) / 7.04 = 455 Watts
4. From Slipwatts vs RPM curves
The 10MC90B20 will dissipate 500 Watts at 1750 rpm.
5. Select 10MC90B20.
Magnetic Particle Clutch for Overload Protection
| Torque Required at Conveyor (T Req) | Speed of Conveyor Drive Roll (N Req) | Motor | Gear Box Ratio |
|---|---|---|---|
| 20 lb. ft. | 175 rpm | 1 hp @ 1750 rpm | 10:1 |
1. Calculate Torque at Clutch (T)
T = T Req / Ratio
T = 20 lb. ft. / 10 = 2.0 lb. ft.
2. Calculate Speed at Clutch (RPM)
RPM = N Req x Ratio
RPM = 175 rpm x 10 = 1750 rpm
3. Calculate Slipwatts (SW)
SW = T x RPM / 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 10MC90B20 will dissipate 500 Watts at 1750 rpm
5. Select 10MC90B20.
Magnetic Particle Clutch for Dynamometer Testing
| Test Motor Size | Full Load Speed |
|---|---|
| 1/4 - 1 hp | 1750 rpm |
1. Calculate Torque (T)
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)
SW = T x RPM / 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 10MCA90B20 will dissipate 785 Watts at 1750 rpm.
4. Select 10MCA90B20.
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) |
|---|---|---|---|
| 12 lbs. | 200 fpm | 3 in. | 30 in. |
1. Calculate Torque (T)
T = Force x Radius
T Start = 12 lbs. x 30in./24in. = 15 lb. ft.
T Finish = 12 lbs. x 3in/24in. = 1.5 lb. ft.
2. Calculate Speed (RPM)
RPM = Velocity/π(diameter)
RPM Start = 200 fpm / π x 30in./12in. = 25 rpm
RPM Finish = 200 fpm / π x 3in./12in. = 255 rpm
3. Calculate Slipwatts (SW)
SW = T x RPM / 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 = 54 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 (RPM) | Time to Stop (t) |
|---|---|---|
| 1000 lb. ft.2 | 360 rpm | 60 sec. |
1. Calculate Required Torque (T)
T = WK2 (rpm) / 308(t)
T = 1000 (360 rpm) / 308 x 60 = 19.5 lb. ft.
2. Calculate Maximum Slipwatts (SW Max)
SW Max = T x RPM / 7.04
SW Max = 19.5 lb. ft. x 360 rpm / 7.04
SW Max = 997 Watts
3. Calculate Average Slipwatts (SW Avg)
SW Avg = √[(t on / t on + t off) x 1/3 x SW Max2)]
SW Avg = √ [(1 min. / 2 min.) x 1/3 x 9972)]
4. From Slipwatts vs RPM curves
The 50MB90B20 will dissipate 450 Watts at 360 rpm.
