If your fan is making a strong crunching sound it's likely to not have been assembled correctly and is struggling to oscillate. Please unplug your fan, remove the base, ensure it's been attached correctly and then add the fan. This should stop the noise.
Please also be aware that fans do make a small amount of noise during normal usage. Please check your manual for the decibel setting to ensure the noise you're hearing is out of the ordinary.
Why is my fan so loud?
