neodymium magnets as linear actuators

[leonyehuda]

Hi everyone,

 

I am trying to build a device hat requires a rather strong pushing force (500 gr. 1000 gr.) within a rather limited space. (9X15X25 mm) with an 8 mm stroke. This force would be required at full extension. Since solenoids, voice coils, latching solenoids etc. don't seem to be strong enough or have a long enough stroke length I thought taking advantage of the power of neodymium magnets towards an electromagnet. Supposing I'd be using a 9 mm diameter and 3-4 mm thick N52 neodymium magnet, could and electromagnet stick to it with a holding power of at least 500-1000 gr.? And will it be able to detach from it by reversing the current?

 

hope someone can help

all the best

[swansont]

In principle, yes. Your solenoid probably can't have a core, because that would stick to the Nd magnet and make it difficult to un-stick. So it depends on how much current and how strong the magnet is.

[Bender]

Maxwell's pulling force: F = B² A / (2 μ0)

 

B = 0.5 Tesla (at best)

A = 9²pi/4 = 60e-6 m²

µ0=4pi e-7

 

max force is about 12 N, so enough for your purpose

 

However:

- B decreases quickly with distance, so at 8 mm, only a fraction of the force will be left

- I doubt you can make a coil this small that will generate such a magnetic flux

- the flux from the coil could demagnetise the magnet

 

my suggestion: use a pneumatic or hydraulic cylinder.