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Exploring Duty Cycle in Miniature DC Motors

December 15, 2022

Selecting a miniature motor for a motion system is rarely straightforward. Not only does every application have its own unique set of requirements, but each motor technology features a variety of operating characteristics that will impact the motion system’s design – and therefore impact which motor (brushless DC, brush DC, or stepper) you select.

One common example of these unique application requirements is having a detailed understanding of how often the motor runs. Mini motors typically do not run continuously, but rather operate for a certain period of time (on-time) and then rest for a certain period of time (off-time). This concept, known as a motor’s duty cycle, is explored in-depth below.

What is a Mini DC Motor’s Duty Cycle?

The duty cycle is the ratio of the time the miniature motor operates divided by the amount of total time for the motion cycle; i.e. the ratio of on-time to off-time of a digital signal. It is typically expressed as a percentage or a fraction of time. The duty defines the load cycle to which the machine is subjected, including (if applicable) the starting, no-load, and rest/de-energized periods, as well as their durations and sequence in time. For example, a duty cycle of 50% means that the motor is powered and loaded for half the time and off for the other half while a duty cycle of 100% means that the motor is powered and loaded all the time.

Selecting a Duty Cycle for Your Miniature Motor

When choosing a duty cycle for your mini DC motor, it is important to consider the amount of time that the motor will be in use. A duty cycle that exceeds what the motor can handle will cause the motor to overheat and fail prematurely; this means that the on-time requirements for the cycle must be balanced so the current that is drawn doesn’t cause the motor to exceed its maximum operating temperature.

Note: Operating a motor above its maximum rated temperature can result in internal component damage. The rate of temperature rise will depend on how much current the motor uses; the higher the current, the quicker the temperature rise.

Surgical Hand Tools and Duty Cycle

When designing a surgical hand tool, it is important to consider the duty cycle as reliability, especially during procedures, is a top priority. A surgical hand tool that utilizes a high-duty cycle motor will be able to operate for longer periods of time and with higher loads without overheating. It is important to take into consideration the requirements to perform a specific surgical procedure so that the correct motor can be selected that is optimized for the application. You can explore all our Surgical Motor Solutions here.

Portescap offers a selection of catalog of application-specific motors designed and optimized for specific surgical procedures. Get in touch with our engineers to discuss!