# solenoid pull force

#### clark.kent156

Joined Aug 17, 2019
50
I need to calculate the power needed to move a linear solenoid. I have a 12v linear solenoid. On the end of it is a small metal plate. 1/2" space, then a neodymium magnet in a fixed position. I want to actuate the solenoid away from the magnet. There is a 2.1lbs pull force between the plate and the magnet. I used a digital fishing scale, attached it to the rear of the solenoid, slowly pulled, and recorded the measurement when the magnetic force broke. What supply, or requirement for a supply, is need to actuate the solenoid? I can change solenoids also to meet the requirement for the supply. Please throw out some theories so I can test them. Thx.

Joined Jan 15, 2015
7,517
You go to a supplier warehouse where you will see a data sheet that looks like this one. You need to know things like Voltage already given, Direction of Force, Stroke length, Duty Cycle, Rod Return Style, Rod Diameter, Force at Stroke Length, Frame Type and other information. Things like physical size and mounting configurations. Long list of variables need known when making a choice.

12 Volts so find a suitable force allowing at least 20% over what you need at least. These units are normally expressed in coil voltage and power expressed in watts. Dividing the voltage into the power will yield the current. So for example 12 volts @ 36 Watts would be 36/12 = 3 Amps so allowing overhead a 12 Volt 5 Amp power source is the minimum. Remember to pay attention to intermittent or continuous.

Ron

#### Sensacell

Joined Jun 19, 2012
3,445
It's going to take a monster solenoid in that configuration, the solenoid force is always lowest when the plunger is extended- right where you need the most force.

I would re-think this concept.

Joined Jan 15, 2015
7,517
It's going to take a monster solenoid in that configuration, the solenoid force is always lowest when the plunger is extended- right where you need the most force.

I would re-think this concept.
Yes, and notice in the example link I gave you the force is only mentioned at 50% of stroke. Keep the above in mind.

Ron

#### clark.kent156

Joined Aug 17, 2019
50
It's going to take a monster solenoid in that configuration, the solenoid force is always lowest when the plunger is extended- right where you need the most force.

I would re-think this concept.
I have about 2 inches of travel, it being the weakest at full extension. What if I get one with a longer reach and have it retracted part way already. When the power kicks on, it's already towards a stronger pull?

#### Sensacell

Joined Jun 19, 2012
3,445
I have about 2 inches of travel, it being the weakest at full extension. What if I get one with a longer reach and have it retracted part way already. When the power kicks on, it's already towards a stronger pull?
Not going to help. This idea is like trying to get fast 0-60 times at the track with the parking brake on full the whole time.

#### crutschow

Joined Mar 14, 2008
34,422
How fast do does the plunger need to move?

#### metermannd

Joined Oct 25, 2020
343
What about going the other way? Let the spring do the work and then use the solenoid to reset everything.

#### shortbus

Joined Sep 30, 2009
10,045
Not real sure what this is being used for, so this might not be an idea you can use. But, what if instead of a pull in solenoid to get your movement you used another type of "solenoid". an electromagnet. With the electromagnet wired to give the opposite pole of the neo-manget, it would then repel when energized. Think of a loudspeaker without a cone, that is the principal they work on.