Assuming the fan has ball bearings, it might just be the grease packing getting cleared away. I've always notice new bearings are more difficult to turn when new that after they have had some life put on them. I would expect this to happen within the first few hours.
I’m writing a shipping vibration requirement for an optical instrument we make and I’m not sure if I have all the necessary details to define it. The purpose is to define what vibration levels the unit can survive so the packaging (crate) designer knows how well he needs to protect the unit. I...
I have an optical instrument that I am drop (shock) testing to determine a spec to give to a packaging engineer who will design the shipping container. What significance does the shock duration have? If I still achieve the same g level does it matter? Is it just a matter of the effects of...