hy rishikesh, it is possible to maintain a cnc machine without using iot4.0; just perform preventive maintenance tasks regulary
if you feel like having some extra$$$, just get in contact with someone like rexroth, from bosch : those guys can implement some senzors and predictiv analitics software; they can monitor pressure, temperature, tank level, oil cleanless, speeds, peaks, positioning accuracy, power units, etc; my advice is to forget about rexroth, and do all these :
... buy a drawbar force gage / retention force measurement
... check periodically machine geometry
... lower the max admisibile servo torque ( so to lower the impact force in case of a collision; i have no clue if this is possible on fanuc )
... use axis load monitor ( if available )
... check if the lube pump is delivering lube where it should
... change retention knobs, at least 1/year, for the toolholders that do roughing operations, or maybe even sooner for <=bt40s
... if possible, don't use same machine for roughing and fininshing
... implement daily, weekly, monthly and yearly maintanence tasks
... be sure that compressed air is dried before entering the machine
... install shower coolant and keep the cabinet clean
if you still feel like having another extra $$$, contact someone like https://machine.report/ in order to gather data about machine status; my advice would be to forget about them, and dig into fanuc system variables ( or functions, if available ), in order to create your own timelines; i can do such things for an okuma cnc, monitoring parameters related to machining / kindly