Innovative iron core linear motor range with vastly reduced cogging forces

Assembly Automation

ISSN: 0144-5154

Article publication date: 1 September 2003




(2003), "Innovative iron core linear motor range with vastly reduced cogging forces", Assembly Automation, Vol. 23 No. 3.



Emerald Group Publishing Limited

Copyright © 2003, MCB UP Limited

Innovative iron core linear motor range with vastly reduced cogging forces

Innovative iron core linear motor range with vastly reduced cogging forces

Keywords: Linear Motor

Iron core linear motor "RIPS" through the price/performance barrier for linear motion applications.

Time and Precision launch innovative iron core linear motor range with price and performance to compete with traditional mechanical systems.

A new range of competitively priced, iron-cored linear motors from Texas-based Trilogy Systems Inc., featuring a unique lamination design that significantly reduces cogging is now available from UK-based motion systems specialist Time and Precision. Known as the "RIPPED" range, they are available in two models with cross sections of 70 and 100 mm2 in three different lengths with peak forces up to 2,100 N for the smaller model to a staggering 4,900 N for the largest unit. The new range will bridge the gap in medium to high force applications between the similarly priced, traditional rotary servomotor/ ballscrew solutions and more expensive "cog-free" linear brushless servos which can be cost prohibitive in many application areas (Plate 11).

Plate 11 The RIPPED range from Trilogy Systems Inc.

Whilst brushless iron-cored linear motors can produce the highest of continuous and peak forces required for many industrial applications, their lack of smoothness has been a restriction in higher performance applications. In the past, this has meant that ironless "cog free" brushless designs have been specified, but these are usually much more expensive than rotary servo/ballscrew systems. In iron-cored linear motors, the cogging or ripple effect is due to the inherent interaction between the leading and trailing edges of the steel laminations as they pass over the pole magnets during motion and is also attributable to the internal lamination teeth passing over the magnets. With the new Trilogy "RIPPED" design, cogging due to the internal lamination teeth is virtually eliminated and cogging due to the leading/trailing edge is significantly reduced. This results in a high performance linear motor system that can compete in price with traditional rotary servomotor/ballscrew solutions and opens the potential for OEMs to design-in linear motors at competitive build costs. Furthermore, the "RIPPED" design does not rely on skewing the magnets to reduce motor cogging, which in turn decrease the motor's peak force, but utilises a patent applied for proprietary design, developed by Trilogy systems.

The "RIPPED" motors also use Trilogy's innovative connector module which includes the motor power and over-temperature connectors as well as digital HEDs, home and end of travel sensors; this makes system design and specifying easier as well as significantly reducing the machine build time. One connector model also features Trilogy's patented LEM magnetic encoder feedback system providing a positioning resolution of 5 mm using the magnets themselves as scales and thus providing another cost saving over other linear motor/encoder solutions. The "RIPPED" linear motors require no specific manufacturer's servo drive module and can be used with almost all brushless drives available. Two lengths of modular magnet tracks allow unlimited length of travel.

The full range of Trilogy Systems linear motors are available exclusively in the UK from Time and Precision, who provide complete integrated motion control systems, sub systems or components as part of their applications solution service. They will specify and supply the right linear motor technology as part of a system solution that also includes the motion controller, motor and drive system, linear bearings and other mechanical components.

For technical information, contact: Gary Livingstone at Time and Precision Industries Limited, Stroudley Road, Daneshill, Basingstoke, Hampshire RG24 8UG, UK. Tel: +44 (0) 1256 365656; Fax: +44 (0) 1256 365645; E-mail:

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