Singapore—Stepper motors have found a new lease on life, thanks to miniaturization and increased automation. Advances in magnetization and improved materials technologies have helped shrink frame sizes from 60 to 15 mm. By 2002, predicts Thomson Airpax Mechatronics Pte. Ltd., 10-mm motors will become part of the mainstream market.
Fresh on the heels of having developed customer-centric applications for its 55- and 44-mm slim motors, the company has now introduced its 20-mm stepper motors into commercial production. Strong understanding of motor stators, improvements in motor assembly, and advances in material technologies—coupled with better coil design—have contributed to the improved stepper motor offerings, says Engineering Director Eric Chia.
Explaining further, Chia states that the three key elements instrumental in a stepper are the motor stator, motor assembly, and the manner in which the coil is designed. Motor stators basically refer to the pole configuration, which is instrumental to the performance of the motor. Thomson's key edge here, Chia believes, is the company's big database of information in having optimized the performance of the end product based on various pole configurations. Likewise, motor assembly is dependent largely on the saturation of magnets, and Thomson has been able to add depth because of its experimentation with neo-magnetic technology. The third element of coil design really depends on the application of the stepper. Chia notes that Thomson is able to enhance performance because of the variety of places where its products have ended up.
With these building blocks, Thomson's anchor offerings now are the new 55-mm, 42L series, 44-mm, and the 20-mm steppers. The 7.5-degree 55-mm stepper features a high torque-to-inertia rating. Offering both unipolar and bipolar versions, this stepper produces 176.5 mNm pull-out torque when driven with a 24V dc chopper (p/n 55M048D1B-5V bipolar version). Having a 4.8W input power per winding, ideal applications include paper feed/sorting functions in printers and wheel positioning in gaming machines.
The 3.6-degree 44-mm slim stepper, producing 30 mNm pull-out torque, is targeted at applications which have space constraints. Hence, it will ideally fit into medical design applications like vitro diagnostic equipment, blood analyzers, and pharmaceutical packaging equipment. And, the newest product to join the family is the 20-mm stepper, whose preliminary specifications include a minimum holding torque of 11.30 mNm and detent torque of 3.53 mNm.
Chia adds that Thomson is able to deliver a prototype for an application within two weeks. "We have developed quite a number of specific products for customers such that 95% of the time, we have a product the customer wants," he says. "For most standard and non-unique applications, we will be able to offer a solution because we have an in-house team dedicated to re-engineering products to customer needs."
Looking ahead, the company is not sitting still as its 10-mm stepper is already on the drawing board. Chia expects the stepper to be ideal for applications like vibrating pagers, which is expected to be a big market in China. However, he cautions, this won't happen before the end of 2001.
For more information about stepper motors from Thomson Airpax Mechatronics: Enter 519