Seemingly Random Low Magnetic Force at Higher Input Current
We designed a solenoid in-house for use on an electro-mechanical flow control device. The solenoid was to be manufactured at an offshore low cost country vendor. Occasionally we would receive solenoid that either had random units that produced low magnetic force or at times complete shipments with low force.
On the drawing is a resistance and inductance spec that we typically use as an indication of the units having the correct number of turns of the proper size wire (resistance) and the proper material with the proper heat treatment properties (inductance). Much to our surprise most if not all of these units would meet these requirements.
However there was one very important physical characteristic that was called out on the drawing, but as it turned out was not always being met. Our vendor insisted that there failure to meet this print requirement was not the issue as they showed how both good and bad part met the resistance and inductance requirement.
What problems were resolved?
Through the use of Infolytica Magnet software we were able to show that it is indeed important to meet the physical characteristic for the solenoid to work correctly at all energy input levels. And that while the resistance and inductance checks told us the proper of amount and size of copper was used and that the individual component where of the proper material and heat treatment, that if the components are not assemble accurately the device will not work due to a flux return path bottle neck.