Many lathes, including good quality ones, are fitted with inverters that have little or no protection against dust.
Typically, the protection will be to IP20, but it should be more like IP66.
Many inverter manuals state that their IP20 inverters should be mounted within a dust-proof cabinet in dirty environments but then supply to manufacturers that ignore this recommendation.
Haydock supply their retrofit control packages in proper steel cabinets but lathe manufacturers usually don't!
This is all to do with money as illustrated by the Invertek Optidrive E3 range of inverters:
https://www.motorcontrolwarehouse.co.uk/invertek-optidrive-inverter.html?kw_rating=40&voltage_input=17The IP66 version of a 1.5kW inverter adds about £60 to the price of the IP20 equivalent. So, for less than £100 saving you will usually get a "not fit for purpose" inverter setup on a multi-thousand pound lathe. Funny old world isn't it?
The miracle is that these unprotected devices work as reliably as they do.
If I'm concerned about dust ingress, I vacuum around the inverter vents regularly and sometimes put some filter material over the vents, also vacuumed regularly. Possibly unnecessary, but gives me peace of mind and should help extend the life of the inverter.
Duncan