Drives and Controls Magazine
Ironless linear motors boost force-to-mass ratios by up to 45%
Published:  14 June, 2019

At the 2019 Hannover Fair, Schaeffler presented a series of ironless linear motors designed to reduce the mass of the primary part without compromising drive forces. The UPLplus motors are aimed, in particular, at applications where the maximum acceleration of linear drives has previously been limited by the relatively large proportion of the rotor mass to the total moving mass.

To tackle this, Schaeffler prints the motors’ forcer coils on circuit boards, resulting in extremely light primary parts. Force-to-mass ratios are said to be 45% higher than similar ironless linear motors. Schaeffler’s engineers also reduced the mass of the secondary parts, improving acceleration and positioning times in multi-axis systems.

In pilot projects, it was found that smaller versions of the new motors could be used in existing applications, to achieve the same performance. This allowed the use of smaller-profile axes, while the lower masses resulted in a significant increase in acceleration. Machine throughput was also boosted, and cycle times reduced. Linear axes using the UPLplus motors are said to achieve an average increase in performance density of up to 40% compared to similar linear motors from other manufacturers.

The new motors will be available in three sizes with active part heights of 30, 60 and 80mm, and up to five primary part lengths. Peak forces range from 120–1,450N and nominal forces from 30–300 N. Parallel arrangements are possible if the force range needs to be extended in an axially restricted design envelope.

The U-shaped secondaries are available in lengths from 90–390mm. Because of their simple design, the drives can be adapted easily to any adjacent structures. The U shape means that the attracting forces cancel each other out, making it particularly easy to implement systems with air bearings.

Schaeffler’s U-shaped linear motors reduce the mass of the primary without compromising drive forces

The UPLplus motors will operate with standard frequency converters and at the corresponding intermediate circuit voltages. This ensures that they can be integrated easily into a wide range of applications.

•  At Hannover, Schaeffler announced that it was renaming its Idam (INA Drives & Mechatronics) division as Schaeffler Industrial Drives.