How to select a DC electric motor
When it comes time to choose dc electric motors for use in products or systems under development or those about to go into mass production, design engineers are likely to base their final motor selection on three key factors: power, speed and shaft configuration. “Ultimately, it’s all about the output,” says Kenn Langosch, Sales Manager for Industrial Motors for Bosch.
Many kinds of industrial and medical equipment applications require the installation of dc motors with a gearbox to reduce or increase the motor’s speed for the application at hand. Langosch says the gearbox-equipped motors are compact in size and offer a good solution for industrial and medical equipment applications where the source of power transmission or control must be able to fit comfortably within a reduced installation space.
Additionally, the gear motors are ideal for applications where reduced weight requirements are also critical. “Think power lawnmowers,” says Langosch. “The dc electric motor in lawnmowers not only needs to be compact in size, but also relatively light in weight to make it easy for the end user to maneuver the mower, whether it is running or not.”
Of the three key motor output factors (power, speed, shaft configuration) deemed advantageous for the successful operation of an application, it is the availability of different shaft configurations that may very well be the most important item on the design engineers’ motor specifications checklist. Langosch says, “Having access to a wide range of shaft configurations can be especially helpful to design engineers during the early stages of product development. It gives them an opportunity to thoughtfully consider each shaft design’s effectiveness for working in tandem with another component. The design engineer’s choice of shaft configuration for an application can also result in time and cost savings during the assembly phase of production.”
Shaft configurations can include:
- Round with a flat
- Round with external thread
- Round with internal thread
- Round with a Woodruff key slot
- Grooved for a snap ring
- Screw type
Bosch dc electric motors include brushless and brush-type motors. Depending on the part number, the nominal power will range from 0.22 W to 2.38 kW; with nominal torque from 2 Ncm to 7 Nm. Langosch said the Bosch i-Business Group offers optimal flexibility in meeting customers’ output requirements by offering more than 500 part numbers for 12-24 volt Bosch dc electric motors. Additionally, the company can modify or enhance the standard Bosch motor offerings to best meet the power or control needs of stationary, portable and battery-powered applications, he added.
The Bosch Group
– Edited by Gust Gianos, Control Engineering, www.controleng.com