The Motor Selection Process

Need help determining the right motor for your application? Check out our Motor Selection Guide or Visit the ISL Motor Database on our website.

The motor selection process at the conceptual design phase can be challenging, but our engineers are here to help. We provide a concierge approach to all of our DC motors and gear motors projects. Our team of engineers work with you to provide the optimal component solution. The following key points can help you determine and select the most appropriate motor or gear motor for our application.

1. Design Requirements - A design assessment phase where the product development requirements, design parameters, device functionality, and product optimization are studied.

2. Design Calculations - Calculations used to determine which motor would be the best solution for your application. Design calculations determine gear ratio, torque, rotating mass, service factor, overhung load, and testing analysis.

3. Types of DC Motors/Gearmotors - The most common electrical motors convert electrical energy to mechanical energy. These types of motors are powered by direct current (DC).
- Brushed
- Brushless (BLDC)
- Planetary Gear Motors
- Spur Gear Motors
- Stepper
- Coreless & Coreless Brushless
- Servo
- Gear heads

4. Motor Specifications - Once the design calculations are performed, and the application parameters are defined, you can use this data to determine which motor or gear motor will best fit your application. Some of the most common specs to consider when selecting a motor or gear motor would be:
- Voltage
- Current
- Power
- Torque
- RPM
- Life Expectancy / Duty Cycle
- Rotation (CW or CCW)
- Shaft Diameter and Length
- Enclosure Restrictions

Gear Motor Performance Curves

A motor's performance and gearbox performance are combined into one graph by displaying three specific parameters. These three parameters are speed, torque and efficiency. These performance curves are essential when selecting a gear motor for your application.

Speed/Revolutions (N) - (unit: rpm) indicated as a straight line that shows the relationship between the gear motor's torque and speed. This line will shift laterally depending on voltage increase or decrease.

Efficiency (η) - (unit: %) is calculated by the input and output values, represented by the dashed line. To maximize the gear motor's potential it should be used near its peak efficiency.

Torque (T) - (unit: gf-cm) this is the load borne by the motor shaft, represented on the X-axis.

Current (I) - (unit: A) indicated by a straight line, from no load to full motor lock. This shows the relationship between amperage and torque.

Output (P) - (unit: W) is the amount of mechanical energy the gear motor puts out.

Gear motor performance curves are a helpful tool when selecting a motor for your application. To get the most out of the performance curves it's important to thoroughly understand the application's requirements. You can use your load and speed requirements to help determine the required torque. Most DC motor and gear motor manufacturers provide performance curves upon request.