The document discusses the importance and functions of mist collectors in metalworking industries, highlighting their role in ensuring clean air and compliance with indoor air quality regulations while reducing maintenance costs. It explains the types of hazardous substances produced, specifically mist and smoke, and describes various methods of mist collection, including electrostatic precipitation, inertial separation, and filter media. A specific product, the Powertech Pollution Controls' oil mist collector, called Mistkiller, is presented as an effective solution for controlling mist in various machining applications.

1. Mist Collection – Why & How?
Metalworking industries use mist collectors on machine tools to help supply
clean air, lessen the negative effects of exposure to metalworking fluids, comply
with indoor air quality regulations, lower maintenance and housekeeping costs,
and increase component quality. The two main elements that are generated in
such metalworking industries are mist and smoke.
Mist – A hazardous substance created during metalworking processes
Mist is a liquid droplet with a diameter of 20 microns or less, formed from
applications that involve the usage of lubricants and coolants, such as metal
cutting, metal shaping, grinding, parts cleaning, and others. For instance, mist
droplets ranging in size from 2 microns to 20 microns are routinely produced
during milling and turning processes utilizing water-soluble metalworking fluids;
and droplets between 0.5 and 10 microns in size are commonly produced by the
same processes utilizing oil-based fluids.
Smoke – Another hazardous component in metalworking environments
Smoke is often a considerably smaller substance than mist, ranging in size from
0.07 microns to 1 micron, and it can either be a solid or liquid aerosol. Smoke is
produced when a supersaturated vapour condenses or incomplete combustion
occurs. Cold heading, straight oil machining of hard metals, using lube oil
reservoirs on large generators, and heat treatment are examples of common
applications that produce smoke.
Mist and smoke may not be visible

2. If you think that you can’t see mist or smoke, means that they don’t exist in your
environment, you may be wrong! Any kind of metalworking processes certainly
produce some or the other kind of smoke or mist, which may or may not be
visible, but is certainly present. And, if ignored, the harm these elements can
cause to the production environment in terms of worker exposure, upkeep and
maintenance, and compliance with emissions or indoor air quality regulations
can be highly dangerous! Although individual droplets smaller than 40 microns
cannot be seen by the human eye, there is strong evidence that smaller mist
droplets are present in most metalworking processes. This means a proper
solution to this issue is eminent. One such solution is to install an oil mist
collector.
What does a mist collector do?
The primary purpose of a mist collector is to take mist and smoke droplets out
of the filtered airstream. Small drops of coolant must be combined into bigger
ones by a collector in order to accomplish this task. The collected coolant must
then be drained from the filters before they clog. There are various ways to
capture such mist droplets, such as electrostatic precipitation, inertial
separation, and filter media.
Electrostatic precipitation
Electrostatic precipitators work by drawing the mist-filled air through an ionizer,
which gives each droplet a positive or negative charge, which are then
subsequently collected by collecting cells, which push and pull the charged
droplets onto the plate using alternating high voltage and grounded plates. As
these droplets solidify on the plates, they are drained out of the collector.
Electrostatic precipitators have a number of benefits, such as the absence of
filters, relatively low energy requirements, and great efficiency when thoroughly
cleaned. Electrostatic precipitators, however, demand frequent and arduous
maintenance requirements. The components inside an electrostatic precipitator
requires diligent cleaning to maintain the effectiveness of charging and catching
the droplets.
Inertial separation
The following is how droplets carried in an airstream are separated using
collectors that primarily use inertial separation. The droplets continue on their
journey as the airstream is redirected around a surface, striking it as they go,
eventually combining with other droplets to drain. Inertial separation comes in

3. a variety of forms and styles, but they all have some characteristics. Inertial
separators, which normally do not have main filters, can function without a
barrier filtering mechanism. Yet, they typically do need fairly routine
maintenance to remove any pollution from the components. Additionally, since
the capture of the droplets depends on them not following the airstream, inertial
separation performs better on larger droplets. Larger droplets are more likely to
hit the capture surface because they have more mass, momentum, and force.
For droplets with a diameter of less than 1-2 microns, inertial separators aren’t
advised.
Filter media
Four filtration processes are used by collectors that use fibrous filter material to
extract mist and smoke droplets from an airstream, namely, sieving, inertial
impaction, interception, and diffusion.
• Sieving is the most common filtration method for bigger droplets, those
larger than 10 microns. When a droplet is physically too big to travel
between two or more threads, the droplet sticks to the fibre as it makes
contact with it, coalesces with other droplets, and then drains from the
collection.
• Inertial impaction is the filtration method that primarily collects droplets
that are micron-sized and bigger. Because of the mass, the droplets are
able to maintain their initial direction even after the media fibre displaces
the airstream.
• Interception is the filtration process that primarily collects droplets
between 0.1 and 1 microns in size. When a droplet follows an airstream
but yet approaches a fibre closely enough to stick to it, interception
occurs.
• Diffusion is a filtration mechanism through which very small droplets, less
than 0.1 micron in size, are mostly collected. The airstream’s molecular
forces, which are influenced by the droplets’ small size, cause them to flow
in the same general direction as the airstream while still being
independent of it.
Once the droplets stick to the fibres, they merge with other droplets on the fibres
of the filter media, and when they reach a sufficient size, gravity will draw it along
the fibre to the point where it will drain.

4. One of the best ways to capture and control the mist and smoke in your
premises is by installing Powertech Pollution Controls’ oil mist collector, which
is trademarked under the name of Mistkiller. This high-efficiency centrifugal mist
collector is designed and developed for the control of most types of mist,
generated by the use of water-based coolants or water-based liquids. This
particular equipment can be easily used for applications involving CNC and non-
CNC machining, cleaning chambers, and spraying systems.