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.