Frequently Asked Questions

Can electromagnets be used to repel as well as attract?
As they are sold, minimal to no repel can be achieved as they are designed to attract. What is needed to repel is a coil around an iron core with no outer shell. This configuration places a north pole at one end of the iron core and a south pole at the opposite end. The electromagnets as they are sold have a south pole and north pole on the same end. One pole is on the outside ring or shell and the other pole is located on the center post or core.

How far away from the electromagnet can I hold attracted material?
The electromagnet achieves its maximum holding force when in direct contact with the attracted surface. You can review the gausses to distance PDF which will give you a better understanding of how distance from the electromagnet decreases the magnetic forces. Gauses-distance.pdf (PDF - 82kb)

Can I use a battery to power the electromagnet?
While the answer is yes, we do not provide engineering services to determine the battery required to power the unit you require. We will gladly provide you with the power consumption specifications for the unit in question and the rest will be up to you.

Does ambient temperature affect the performance of electromagnets?
Yes. As the ambient temperature raises so does the resistance of the coil reducing the ampere turns which in turn decreases holding force. Likewise, low temperatures lower the resistance of the coil decreasing the resistance which in turn increases the ampere turns thus increasing the holding force. Typically, normal operating temperatures will not produce significant performance changes. Extreme conditions hot or cold will affect the performance accordingly.

Can the holding force of the electromagnet be adjusted?
Think of your applied voltage as a gas pedal. As you increase the applied voltage to the electromagnet the holding forces increase. So if you have an electromagnet that is rated for 24 vdc, and you only apply 6 vdc the holding forces will be significantly less than when the voltage is at the rated voltage, 24 vdc, of the unit. Likewise, you can apply 36 vdc to the 24 vdc rated unit and achieve in some cases, greater holding force than the rated holding force. The risk with overdriving the unit is that the coil may burn out as the internal coil temperature rises above the intended design parameters.

Is an electromagnet that is rated for 24 vdc stronger than a unit that is rated for 12 vdc?
No. The coils are designed to achieve a specific holding force at the rated voltage. For example, a EM100 with a 24 vdc rating will hold 25 lbs if the applied voltage of 24 vdc is applied to the unit. Likewise, a EM100 with a 12 vdc rating will hold 25 lbs if the applied voltage of 12 vdc is applied to the unit. The different voltage ratings provide engineers with design flexibility enabling them to match the electromagnet to their power supply.

Can I attract any metal with an electromagnet?
No. Electromagnets and permanent magnets alike attract metals with iron contents. The higher the iron content the greater the attraction. The lower the iron content the lower the attraction. Electromagnets and permanent magnets for example will not attract metals such as, aluminum, brass or gold to name a few.

How are your holding forces calculated?
Our electromagnet holding force ratings are based on an electromagnets attraction to a .250" thick piece of 1215 CRS or 1010 steel plate that covers the full diameter face of the electromagnet. The actual rating is based on suspended weight from that plate and is essentially a drop test. The rating given is the weight at which the magnet will not drop its weight thereby its maximum holding force. This test assumes only directly suspended loads and does not take in to consideration any sheer forces.

Does the thickness of material attracted effect holding forces?
Yes the effectiveness of an electromagnet is greatly affected by the material it is attracted to and the thickness thereto. If you have less than .250" thick material you may begin to see losses in holding forces particularly with our larger units as the magnetic saturation point in the attracted material is reached more quickly due to their stronger magnetic fields. Smaller diameter units may be less affected by thinner materials however; all are tested and rated based on their attraction to .250" 1215 CRS or 1010 plate steel.