How are fans of the convection ovens able to withstand such high environmental temperatures?
In: Engineering
Because they’re made of metal and/or high temperature resistant material.
There are plenty of materials out that hold up in temperatures of a couple hundred degrees, the average temperature of you oven.
There isn’t really any material in a fan that HAS to be plastic or soemthing that wouldn’t stand up, so it isn’t really a problem.
Have you ever [seen one](https://cdnimg.webstaurantstore.com/images/products/extra_large/411699/1654200.jpg)?
They’re not made from materials which can’t handle the heat. They’re mostly metal with a small amount of high temperature resistant plastic.
E.g [Here is some nylon](https://www.mcmaster.com/plastics/performance-properties~high-temperature/wear-resistant-nylon-film/) that could be used for oven fan bearings. It’s good up to 450f.
The fan is metal as others have said, but the motor is insulated from the high temperatures, and the bearings are shielded from the heat and strong enough to resist being damaged by the load of the fan
The metals themselves in the fan and motor aren’t fazed by mere 500F degree temps. The main potential issues would be:
A) degradation or melting of the insulation of the windings in the motor leading to a short circuit.
B) changes to the lubrication properties of grease or oil in the motor’s ball bearings and/or evaporation.
Note that the oil in a car’s motor needs to be changed every so often because, among several other reasons, high temperatures of certain engine parts like pistons and exhaust valve seats degrade the oil slowly.
C) Reduced cooling ability of air flowing through the motor.
For this reason the wires in the motor may use fiberglass or teflon insulation or other high temperature materials.
Bearings containing high temperature stable grease are used. Ceramic ball bearings may also be used. These can run without lubrication.
Provisions are also made for extra cooling in the motor to increase the air volume that can travel through it. The motor will be de-rated, that is: wired in such a way that the current and power drawn by it will be less than it could be configured to pull at room temperature. This reduces heat build up in the windings.
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