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CNC Machine Shop Oily Floor

Main Causes of Oily Floors in Modern Machine Shops

Tips for Eliminating Slippery Oily Floors

The air filtration (MistBuster – TriMist) system on the CNC is not working correctly causing oily floors. Make sure the air filtration unit is on and that the blower is running. Keep in mind that electrostatic air cleaning units like Mistbuster and Trimist have indicator lights that must be ON / glowing orange – green or red. Refer to “Mistbuster Cleaning Tips” – for more detailed information. NOTE: The unit blower will run even if the electrostatic cells are not being charged. In this case the machine will be running with no indicator light, and as a result not filtering any air from inside the CNC cabinet.

Check the Chip Conveyor on the CNC unit. I have seen many instances where mist is slowly bellowing up from the chip conveyor causing oily floors. The chip conveyor removes recently generated scrap metal from the bottom of the CNC, pulling the metal chips up and out the side, dumping them into a chip barrel. These scrap metal chips are hot, oily and smoke as they are being removed. Smoke / oily mist rises and bellows out the top and side of the conveyor and into the air. The enclosed chip conveyor is acting like a chimney. In each case there was a mist collector mounted on the CNC. The problem is that the mist collector is not generating enough negative pressure inside the cabinet to prevent the mist from escaping out the conveyor. The solution to this problem; easiest first – more complex later.

  1. Turn the variable speed control knob on the Trimist or Mistbuster so that the unit is filtering the maximum amount of air. Note: Filtering a higher volume of air per minute means that you are filtering the air less efficiently = mist blow-through = oily mess. Sometimes turning up the suction works, many times however it does not.
  2. Add another suction point on the conveyor in order to capture the mist. This can be done by mounting an inlet collar right on the top of the chip conveyor and also connect it to the Mistbuster or Trimist unit. The inlet plenums for these units can accommodate (3) inlet collars for multiple source capture collection points on the CNC unit, including the top of the chip conveyor.
  3. Put a Post Filter on top of the unit. There is an easy way to cheat if the unit is under sized for the CNC. Place a Post Filter on Top. You can purchase HEPA post filters, but what I realized is that in most instances, a HEPA grade post filter will cause more problems because it reduces the air flow by such a drastic amount, that the mist generated in the CNC cabinet escapes from the chip conveyor or out the bottom. A much better solution; purchase a post filter that is NOT HEPA grade. There are post filters that are 85 – 95% effective and are able to “polish” off any mist laden air that passes through the electrostatic cells.
  4. If the unit still does not filter the air generated in the CNC cabinet, even with a post filter. I would say that you need a larger mist collector mounted on the CNC which would create enough negative pressure inside the cabinet so that the mist doesn’t escape the CNC enclosure and the chip conveyor. This is not the end of the world because many times the larger Trimist and Mistbuster units will have the same footprint as the smaller ones, so they fit on without too many complications to prevent oily floors.

Contain the Oil Mist when cleaning off the recently machined part with compressed air. I have seen many instances where the CNC operator is holding a recently machined part and is cleaning it off using compressed air outside the CNC machining center. The emulsified oil is being discharged into a fine mist in the ambient factory air. This makes a mess over time around the CNC unit. Blow off the parts in the CNC cabinet or an enclosure that will contain the oil.

If you are not sure what is going on with your air filtration system for your CNC machine, maybe it is time to have a professional take a look at what you have and suggest how to make the system more efficient without spending too much money guessing.


By: asc2863
In: Common Problems