Selecting a DC Motor for 50kg Project

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To select a DC motor for a 50kg project, the required force is calculated as 38.1N, leading to a torque requirement of 2.1Nm. The estimated power needed is around 56 watts, but it's crucial to verify this against the motor's torque vs. speed curve provided by the manufacturer. This curve will indicate whether the motor can deliver sufficient torque at low speeds, which is essential for the project's acceleration needs. Additionally, understanding the relationship between horsepower and torque can help ensure the motor meets operational requirements. Proper selection involves checking specifications in a catalog that aligns with the desired speed and power range.
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Hi all, I need some help on how to select a DC motor for my project.
Basically, I want a 50kg mass to accelerate to ~1.5 m/s in ~2 seconds. So by F=ma, F = 38.1N.
Radius, R, of the wheel I am using is 0.0564m, thus torque required to move the is =FxR = 2.1Nm.
Using a formula I found online. Power = (nxM)/1350, where n=speed(RPM), M=torque(oz.in)
plug in the numbers with correct units. I got ~ 56 watts. So does that mean I need a motor of at least 56 watts?
I don't have any engineering background so not sure if I did these calculations correctly.
Thanks for the help
 
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Power is one thing you need to look at. Another thing is you need to get a curve from the manufacturer that shows the motor's torque vs. speed. This will tell you if the motor will be able to move the item at the speeds you want it to. The overall power may be correct, but if you need a lot of torque at the low end, you need to make sure that your motor does that.
 
Well in US units the Horse Power (HP) of a motor is equal to...

HP = (n*T)/5252

where,

n = rotor speed
T = torque

[5252 is a conversion constant and is equal to 33,000/(2*pi) exactly].

To find the power in watts multiply the HP by 746.

This will be how much power the motor uses while operating at rated conditions. However, like Fred pointed out, you'll need a motor curve to see how it will operate at other than rated conditions.
 
DC motors

DC motors sre for precise torque/speed control or positioning systems...if you really need to select a DC motor, you need to find a catalogue for speed, W and A range you are working with...
 
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