Linear motor, actuator - Contamination??? Magnetic Particles

[PNA]

I am specing out a linear motor.
there is going to be a lot of fine ferrous metal particles and i am concerned with the magnetic properties of some of the drives, that the motor will be a huge magnetic science experiment.

Has anyone had experience with this?

Thanks in advance

PA

 

[blacksea]

If your application is sensitive to magnitic fields, than look at linear motor from Aerotech or Anorad.

 

[PNA]

thanks
i'll look that up

i am worried that unless i choose a timing belt driver or ball screw style linear actuator, i'll have a major collection point for debris, i do however like the cleaner lines of the magnetic driven actuator

regards

pa

 

[ScottyUK]

How big is this application? How accurate does it need to be? A hydraulic solution can achieve accuracy down to one thou or better given a good feedback transducer, with the potential of very large load handling capacity. A bit more detail in terms of what you are moving or positioning would help.


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If we learn from our mistakes I'm getting a great education!

 

[PNA]

approximate thrust load is 200 lbs
reciprocating motion
almost like a long stroke jack hammer
duty cycle of 50%
repeatability to within 5 thou

(and i would rather not get into a hydraulic pump, etc.)

the heat generated and seal life at high repeated speeds would have maintenance issues

 

[itsmoked]

Sounds like the perfect application for a bellcrank. Think 'steam locomotive'.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[sreid]

An exposed permanent magnet linear motor will attract steel chips like a vacuum. Can you be more specific about the load, stroke, speed, etc.

 

[PNA]

bellcrank would have too much wear

 

[sreid]

Exlar is known for beefy, fast Electric Cylinders.

http://exlar.com/#cycle

 

[ScottyUK]

Why would the bellcrank have too much wear? Think how many cycles a mainline steam locomotive conrod makes per second. Pretty quick isn't it? Wear was not a significant factor on those machines although obviously some wear occurs over time as it does in any mechanism. A badly designed bellcrank would have wear problems in no time flat; a well designed one should last years with minimal intervention.

You might want to look at

http://www.powerjacks.co.uk

if you fancy the electric solution. Failing that,

http://www.rexa.com

have some nice self-contained hydraulic packs to which you supply power and a 4-20 mA demand signal. The oily bits are not something you need to get too involved with. Moog have something similar but their sales guy in the UK pissed me off so bad that I can't be bothered with them even though I like the build quality of their products.


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If we learn from our mistakes I'm getting a great education!

 

[PNA]

thanks for all your replies!

The bell crank needs to have total adjustability in terms of stroke length and stroke position (over 42"), for this application, i dont think something like that will work

PA