THE ORIGINAL MAGNETIC PARTICLE SPECIALISTS

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

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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

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Torque Required at Conveyor (T)Speed of Conveyor Drive Roll (N)MotorGear 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

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Test Motor SizeFull 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)

Chart 2




Magnetic Particle Brake on a Non-Contact Unwind

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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

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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)

SW avg = 406 Watts
4. From Slipwatts vs rpm curves

The 50MB90B20 will dissipate 450 Watts at 360 rpm.

5. Select 50MB90B20.



Selection - Heat Dissipation (Slip Watts) vs. Speed Chart (RPM)

Chart 1