Baldor HyCore Linear Motors

[gymcaster]

Has anybody had experience with linear motors such as the Baldor HyCore motors ?

I wondering if these could be used in a 3-axis gantry router for woodworking?

Kevin

[gt3073b]

I have not used those, but I have experience with other linear motors.

Linear servo motors are very fast (10m/sec, 100m/sec^2 accel), very accurate (with the right scales), and VERY EXPENSIVE compared to a servo and ball screw module combination. I've used linear motors on roll grinding machines were the backlash of the best ball screws is still a killer. Grinding tenths with a big linear motor is common. Most linear motors are not a bolt on unit though. The motor must be so tightly integrated into the machine design that the linear bearings, magnets, carriage, scale, and scale reader must be mounted by the machine builder and held to very tight tolerances. Dragging the reader on the scale is a great way to destroy the scale and possibly the motor. Crashing the carriage into the magnets usually destroys both ($$$$) and requires serious time and effort to replace. Absolute encoders are highly recommended so you don't have to re-commutate the motor every time you power up the system. Also, liquid cooling is not uncommon to dissipate the high heat generated in the relatively small carriage.

Force-speed characteristics are nearly constant right up to the rated speed, just like on rotary brushless servos.

Linear steppers, on the other hand have the advantage of being able to run open-loop (no encoder) and don't require commutation like the servos do. They have basically the same force-speed characteristics of rotary steppers where the force is very high at stand-still and dropping off very rapidly as speed increases. They are probably orders of magnitude cheaper than their servo counterparts though.

Bryan.