The HoneyComb series of X-Y motion bases come in sizes from 375 x 375 mm up to 750 x 1,500 mm.

A lot of medical manufacturing and lab equipment use X-Y positioning devices driven by ball screws and servo motors. While such devices work reasonably well, accuracy gets expensive and falls off with wear.

A recent X-Y positioning base that uses linear stepper motors overcomes the drawbacks and can increase productivity for a wide range of medical machinery that use traditional motion generators, says developer Baldor Electric Co, Fort Smith, Ark. (baldor.com). The company says a honeycomb-structured of composite material in the base reduces the cost of applying advanced linear motors and provides machinery builders with a competitive alternative to traditional mechanisms such as rotary motors and ballscrews or belts. Prices start at $7,000.

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The HoneyComb Series of X-Y bases come in seven standard sizes with square or rectangular working areas ranging from 375 × 375 mm to 750 × 1,500 mm. The forcer or actuator moves at speeds up to 1.5 m/sec and at resolutions of 2.5 ìm and repeatability of better than 2 ìm. They operate friction-free without backlash and no wind-up, an improvement over traditional mechanical transmissions. And an air bearing eliminates lubricating oils and greases.

The moving element floats on the air bearing and uses two linear-stepper motors mounted at right angles to each other to push in X and Y directions. The forcer comes in six sizes and in two or four-phase configurations, depending on the application's force and resolution requirements. The maximum static holding force is 134 N on the largest design.

The 2504 performance curves for force and voltage versus speed are for the largest base. The 0602 unit is the smallest.

Multiple forcers could mount on the same base with overlapping trajectories. A high attractive magnetic force between forcer and base, up to 1,780 N on the largest unit, means that the base can be mounted vertically or face down if the application demands. Controls can be standard units often applied to linear stepper motors, although one is needed for each axis.

The base's composite honeycomb structure simplifies mountings because it weighs up to 70% less than the weight of previous models. For instance, the base with platen and forcer weighs as little as 22 lbs. for the smallest units. The company says the bases come ready to use. Engineers need only supply power to the forcer and air to the bearing. Custom size bases are also available.

The 2504 performance curves for force and voltage versus speed are for the largest base. The 0602 unit is the smallest.