Re: Re: linear servos

While at the University of Stuttgart de over the holidays, I saw linear
motors used with a 30 hp spindle, parallelkinematics machine (aka Stewart
Platform, aka hexapod). To demonstrate the rigidity of the machine, Till
took a 0.200 face cut on a 16 inch square aluminum plate with a ~4" end
mill. Full width cut using about 60 ipm. There was a scarry shower of
coolant and curls inside the windows. I couldn't even hear the individual
inserts as it made the cut. Very nice surface finish. I have no idea how
fast the spindle was turning.

The department there has done a lot of study of linear motors to find ways
to improve rigidity. These were as solid as any ballscrew and slideway
that I've seen.
--

Ray


From: Jon Anderson <janders@...>

carlcnc@... wrote:

> I am looking at some big linear servos,price is right but can't
> find documentation of how much force or "thrust" they are capable of.

Can't help with real numbers, but just read an article in Modern Machine
Shop about linear motor EDM's. Key advantages are very high
accelerations which helps to self flush the pockets. However it mentions
in discussing the advantages over ball screws, that lack of torque at
low speeds is a disadvantage that really isn't a disadvantage for EDM
since required torque loads are very small.
Of the machines I've read about experimenting with linear motors, it
seems it's being used for very high speed machining, 20k+ rpm spindles
contouring at speeds up to 1200 ipm and taking light cuts.
If you get these, would hope you keep folks up to date on your progress.
The instant I first saw linear motors, I wanted to build a blindingly
fast bench top machine. Maybe when linear motors are availble on eBay
for about what used servo motors go for....