Solidity Effect of Steel to Magnetic Force

The simple answer is NO.

The copper shading ring shows that the core is laminated, each lamination is insulated from it's neighbour. Machining will destroy the insulation, along with disrupting the magnetic path and cause overheating.

I thought your previous post regarding an electromagnet sounded strange, what you have here is an electromechanical solenoid, not an electromagnet (similar principles, completely different application).

http://en.wikipedia.org/wiki/Solenoid

http://www.detroitcoil.com/PAGES/What%20Is%20A%20Solenoid.pdf

You cannot replace the metal core with a hollow tube as there will not be enough mechanical force generated to move the tube.

You can mechanically limit the solenoid slug travel and get some strong push or pull forces you can use but based on your description it is unlikely you will be able to use the solenoid in the way you are describing (especially as the amount of force generated on the solenoid slug varies depending on how far the slug is within the solenoid coil).

Can you describe your application in much more depth please? Exactly what are you trying to do?

The solenoid looks familiar I'm sure I've used them years ago. What's it off originally?

I don't know, it said it can lift up 150N at 50mm, only cost 30 bugs

Sorry to pee on your parade yet again.

But the old grey matter dried out enough to remember things about these solenoids. They work fine to pull in and then hold a load. While holding the load the faces under the curved bit need to touch the yolk, there will be a small air gap at the bottom where the shading ring is. This is why I remember them, the inside of the coils would get a build up of sh1t in them, stop the faces touching and they burnt out! (They were used on Locker rotary batch weighers circa 1945). (I'm old, but I'm not THAT OLD!)

If you want a reciprocating machine it's going to be very noisy with the faces hitting and don't expect a long life from it.

SORRY!

I think adding suitable rubber as seperator can reduce the noise to a certain extent.

Of course adding a rubber separator can reduce the noise, but it will also reduce the pull (especially holding pull) significantly. Remember that the magnetic pull is inversely proportional to the square of the gap, so that last tiny bit of motion is extremely important to the holding power of the solenoid.

If a solenoid could pull equally well with a hollow plunger, they would already be made that way!

When you say reciprocating, it sounds like you are trying to build some kind of an engine. That copper ring, as someone else mentioned, indicates that this solenoid is intended for use with AC. AC solenoids can only pull. For a reciprocating engine, you probably want to push and pull. In most cases that means using a permanent magnet or two electromagnets.

Again, as someone else pointed out, if you tell us what you are trying to accomplish, perhaps we can be of more assistance.

You have a very old solenoid coil there. The ones that I have worked with in the past were normally held open by a spring and when the coil was energized the plunger would pull down. The plunger was connected what ever device that needed actuating.

If the plunger was stuck in the up position the coil would burn almost immediately. Modifying the plunger/ piston will not work as both the piston and the coil frame are comprised of steel laminations to break up the eddy currents in the parts. the same idea is used in a transformer.

You can use it as you intended, as long as you don't mind the noise as the plunger slams into the coil frame. The other thing is that you cycle it rapidly, it will over heat and fry or the constant cycling will cause both the plunger and coil frame to distort and jam.

http://cr4.globalspec.com/thread/60713?frmtrk=cr4sd#newcomments