Technical DataSelection of DC Motors

Selection of DC Motors

To make a best selection, it is necessary to select either a coreless, iron core or brushless motor in consideration of the power supply, control, running conditions, etc. If you want us to select one for you,please confirm the following conditions and contact our Sales.

  • Power supply conditions
    • Range of voltage to use, rectified power supply or battery, need of current limiter.
    • Need of PWM control, voltage fluctuation control, etc.
    • Need of encoder.
  • Running conditions (continuous, intermittent, forward/reverse, drive time, lock, short brake).
  • Environmental conditions (temperature, atmosphere, etc.).
  • Dimensional restrictions including the gearhead and encoder.

A procedure to select a motor and gearhead using basic parameters presented by the customer will be explained below.

An example of basic parameters

Supply voltage U=12V
Rated speed Nr=90min-1
Rated torque Tr=40mNm
Size (diameter, length) Φ16 mm max., length 50 mm max.

Motor-based Selection

1 DC Motor output

Calculate the motor output (W) based on the torque and speed that you require in your application. If you plan to use a gearhead, it is necessary to select a DC motor of an output calculated in consideration of the gearhead efficiency.

For a target of 90min-1, assuming you select a DC motor speed of 9000min-1 and gear ratio of 1/100, calculate an output including the efficiency. (Spur gear 5 stages: 59%)

2 Voltage and size

In consideration of the voltage supplied to the DC motor, size (diameter and length) and an output greater than the DC motor rated output calculated above, make a final section of a motor.

Model selected:SCR16-2502 (12V, 0.71W)
Outside diameter Φ16mm, length 42.75mm total

3 Gearhead selection

Select a gearhead in consideration of the rated allowable torque and size (diameter and length). (The gearhead must be used below its rated allowable torque.) Select a gear ratio to achieve the required speed and allowable torque.

Model selected: RA-16R 1/97 (rated torque 49.1mNm, efficiency 59%)

Size-based Selection

Where your product design poses restrictions on the size of a motor or gear motor or when you are currently using a DC motor or DC gear motor and are looking for an alternative, select a suitable motor based on sizes.

1 Rough selection based on size

Make a rough selection based on the size (diameter and length) of the gear motor.

Model selected: Gearhead/RA-16R
Model selected: DC motor/SCR16-2502
Outside diameter Φ16mm, length 42.75mm total

2 Selection of gear ratio

Confirm the power supply voltage to be supplied to the DC motor and select a gear ratio from the DC gear motor specifications, referring to the allowable rated torque and rated speed. (Please note that the torque to use actually must be lower than the rated torque of the DC gear motor.)

SCR16G-SR2502A-12, gear ratio 1/97
89.7min-1 , 44.9mNm