Solenoid getting too hot

[varunme]

" i used 50, now used 30. " 50 or 30 what?, turns, gauge of wire?. . .
Frank

It reffered to guage

To reduce the heat you need a proper magnetic core, or more turns of wire, or thinner wire that has a higher resistance, or less voltage or all of these.

core is just 6mm soft iron tube, with brass coating.

 

[Audioguru]

A metal tube is hollow and is not a good solid magnetic core. Is the force from the electromagnet strong enough?

 

[varunme]

force is strong but not upto what i intended, but my application needs a hollow tube through which a needle moves

 

[varunme]

i cant use a iron needle which is a solid core, since the iron get sticked to the electromagnet and will not move, so the needle is plastic

 

[Audioguru]

A solenoid is a coil of wire that has a moving solid iron core. The core is the moving plunger.
The core is held away from the coil by a spring and when the coil is energized its magnetic force pulls the core into it.

I do not know why you have a iron tube and a plastic needle.

 

[varunme]

@Audioguru, the method you said will work for pull, I want to make push mechanism, if a spring is used, it will be weak, if the magnetic pulling used, it will be strong and can be held strongly...

 

[Audioguru]

A push magnetic mechanism using a DC solenoid needs to have a magnet or another electromagnet as the moving core.

A magnet or electromagnet attracts (pulls) iron. Two magnets with opposite poles (north and south) attract (pull together) and two magnets with the same poles (both north or both south) push each other away.

 

[varunme]

oohh, i designed such that the iron piece attracts towards the sides of the iron pipe which is connected with the needle which will act as the push machanism, thank you

- - - Updated - - -

like this
https://www.adafruit.com/blog/2012/01/30/solenoid-test-using-adafruit-small-push-pull-solenoids/

- - - Updated - - -

If the attachment through the centre is iron then it will not move isnt it, it core has to be at the side, isnt it?

 

[Audioguru]

The solenoid from Adafruit uses a solid iron moving core that moves back and forth in the hole in the coil, and a spring. One end of the core pulls when the other end pushes. The solenoid in my doorbell (ding-dong) is like that, when its solenoid is activated it pulls on the core which hits the "ding" bar and when the button is released a spring drives the core back and it hits the "dong" bar.
The solenoid from Adafruit draws 100mA from 24VDC so its coil's resistance is 24V/100mA= 240 ohms and its heating is 24V x 100mA= 2.4 Watts.
How much power is your solenoid's coil using?

 

[FvM]

Instead of posting vague information in little slices, how about a drawing of your magnet system? (along with the numbers that Audioguru demanded).

 

[varunme]

This is my whole system

- - - Updated - - -

it draws 500mA at 12V, 6W

 

[Audioguru]

I do not see if the hollow iron tube is fixed to the plastic needle or if the iron tube slides up and down on the plastic needle, and I see no coil.
Please show where the coil is located.
What is supposed to move, the iron tube or the iron block?

6W is a lot of heat if it is small.

 

[varunme]

I do not see if the hollow iron tube is fixed to the plastic needle or if the iron tube slides up and down on the plastic needle, and I see no coil.
Please show where the coil is located.
What is supposed to move, the iron tube or the iron block?

6W is a lot of heat if it is small.

iron block moves, which inturn moves the needle inside the iron pipe, the reverse is done by spring, the coil is above the iron pipe

 

[Audioguru]

Usually the plunger in a solenoid is a solid iron rod. I don't know why you do it differently.
The hollow iron tube will not create as much magnetic force on the iron block as a solid iron rod that is pulled into the coil.

 

[varunme]

I made it hollow since the needle has to move inside through to otherside

- - - Updated - - -

ok, do you have any idea of modification for this?
yes, the pulling is not so strong

when i check inside a commercial solenoid, it has a solid iron rod which does the pulling, but if i use iron rod then it cannot move inside

 

[FvM]

Massive rod or iron cylinder isn't the point.

The position of the air gap matters, also the cross-section of the iron core. A thin-walled tube e.g. won't work well. You also should have noticed that the commercial solenoids have a magnetical return outside the coil.

For maximum force, the magnetical circuit is closed with the exception of the variable air-gap.