Question about an iron bar in the middle of a magnet.

[rukiddingme]

If I drill a hole in the middle of a magnet and place an iron bar through it, does the pull force increase, decrease or does it stay the same?

[profitis]

thats a very interesting question.im imagining all forces will neutralize in dead-centre of the hole q.v. like a smot-ball at the centre of two bar mags simply reacting to the one vector.mmm

[broli]

I don't think there's a clear cut answer to this as there could be many variables involved. The size of the hole matters, the distance between the magnets matters the permeability of the material in the center matters.
A software sim that can go through all those variations in one go can give you a 3d data plot to show all 3 variables at once. Here's a simple quick sim I did for you through in FEMM. Which has 3 variations:

1) no hole
2) hole filled with steel that has a relative permeability of around 1000
3) hole filled with air

I hope that helps you out.

[rukiddingme]

Thanks