Two of the primary methods of removing oil mist and smoke from machine tools with mist eliminators are electrostatic precipitators (ESP) and centrifugal separators.  Although these 2 types are both designed for oil mist collection, the technologies employed are vastly different.

An electrostatic precipitator mist collector (like the Trion Mini Mist Eliminator) has an  ionizing section to charge the incoming particles, and collector plates that are oppositely charged, to collect those particles.  When the oil mist and smoke are drawn into the unit, the collector plates act like powerful magnets, removing oil mist particles from the air.  Because there are no woven media filters to become clogged with oil, airflow can pass through the filtration elements unimpeded, maintaining a consistent capture rate.

Centrifugal oil mist eliminators work by using a high-speed spinning drum that tosses heavy oil droplets into an outer collection chamber that employs hoses to drain the oil back to the machine.  A centrifugal separator is effective on metalworking fluids only.  A high quality HEPA after-filter is required to collect fine oil mist and smoke.

Drawbacks of Centrifugal Mist Eliminators:

• Drum spinning at high speeds (3,400 RPM) cause dramatic vibration and noise
• Media filter replacements are costly
• Centrifugal mist eliminators require an electrician to handle power and controls
• Mounting hardware is always required
• Due to constant vibration, many expensive part replacements are required for items like motor mounts, drums, drum pads, flange adaptors and stands
• Demands an exhaustive maintenance schedule

Benefits of the Electrostatic Mini Mist Eliminator:

• Electrostatic collector plates are easily washed off, eliminating expensive filter replacements
• Quiet and unobtrusive - performance without interference in your production process
• No electrician needed for set-up; unit simply plugs into a standard outlet
• Easy installation - the Mini M.E. easily bolts onto your machine
• Helps save you $$$ - the Mini M.E. is very energy efficient and virtually maintenance free

The first of these case studies, at least the first one posted on misteliminators.org, involves a machine shop dedicated to fabricating steering columns for automobiles. The following details describe an alternate installation method that saved this particular company thousands of dollars.

A few months ago, I received a call from a prominent automobile steering column manufacturer in regard to a machining process that was spraying enough oil-based mist to pose a potential health hazard to the machine operator as well as contaminate the surrounding areas. As we were discussing the application over the phone, it seemed as if it was going to take quite a bit of airflow to address this issue.

This application was taking place in a semi-enclosure, meaning that there were fixed openings all over the enclosure…the bottom and top were totally open, and there was an access window for the machine tool operator. I began to size for the fixed openings (100 cfm per sq. ft. of opening), but based on my experience with mist collection, this just seemed like far too much airflow for the amount of coolant overspray.  Fully enclosing the process is ideal for mist collection.  If not possible, the next option is using ducted source capture hoods.

Do you have a similar coolant mist problem?

Though it is contrary to our regular practice, I set up an on-site inspection since I happened to be passing through that area anyway. Generally on-site inspections are unnecessary.  We have had a 100% success rate for specifying equipment over the phone or internet.  This practice keeps our price to the absolute minimum and saves our customers money.

Once at the location, I asked the shop foreman if he could enclose the process at all. He replied that it may be possible, but not likely.  So we moved on to considering ducting the equipment. We don’t have to enclose this process if ducting capture hoods is feasible within the area. I asked him if he’d like to save some money by fabricating his own capture hoods and performing a slight modification to the semi-enclosure. Since the facility had the capabilities, he was happy to make a couple of sheet metal hoods.

What we decided to do was this: He could mount the mist collector above the top opening, attach a source capture plenum (for ducting), and run (2) 6" flex hoses down into the enclosure. From there, he would attach the hoods and position the hoses directly in front of the spray nozzles. After we both agreed that this would be the optimal solution, he requested pricing information on the spot.

I called one of my colleagues, Rod Yarbrough, and asked him to fax over a copy of the price sheet for this equipment. The foreman and I shook hands, and I headed back to the office. By the time I arrived back in my office, there was a purchase order waiting for me. I called my new customer to let him know that I received the PO, and we would process the order immediately.

The next week, I received a phone call from my customer… this installation worked so well that he wanted to order another mist collector immediately!

I was very satisfied with the way that everything went off without a hitch, and that we were given the opportunity to brainstorm this application. Not only did the extra care pay off by allowing me to provide my contact with a highly effective piece of air pollution control equipment while keeping the equipment cost at a minimum, but it gave him confidence and trust in my pollution control company, and the industrial equipment we provide.

More success stories to come, as we continually strive to fit our clientele with the best service and mist collection equipment available!