In a machine shop environment, all kinds of physical dangers can arise during manufacturing. Operators, depending on how safe the environment they work in, may be exposed to such risks as slip-and-falls, lacerations, lifting-related strains, or burns. As such, certain safety measures are typically taken which all operators need to adhere to for their own protection. Manufacturing technology, be it a small-scale CNC shop or industrial robots worth millions of dollars, also need to meet certain safety policies in order to operate. There’s another hazard that’s rarely mentioned, however, because it’s “invisible”. If you’re a machinist or frequently work with machine manufacturing you know I’m referring to oil mist.
When you need to cut metal or shape it together in a certain way, typically the industry uses an assortment of oil-based fluids that act as coolants and lubricants within the processes of milling, machining, and metalworking. The cutting, sawing, polishing, and grinding of metals in conjunction with the use of these cutting fluids produces a mist that is dispersed into the air. In a closed environment such as a factory or a machine shop, a mist can linger in the atmosphere and pose a serious health risk to employees. The microscopic metallic residues in suspension in the air and the mineral oils are potentially carcinogenic, they can enter into the respiratory system and lean on the skin causing problems of allergies, dermatitis, and other more serious pathologies. Skin-related afflictions can occur: contact dermatitis, allergic dermatitis, and varying degrees of acne are some of the rashes and skin conditions that can develop when the mist is prevalent in a worker’s daily environment. The most commonly reported health issue, however, involves possible damage to the respiratory system: bronchitis, bronchial asthma, chronic coughing, and labored breathing. Besides direct health hazards, oil mist can stick to virtually every surface increasing the risk of accidents from slipping and insecure object manipulation.
Alright, so oil mist – something we can’t really see – is a real bugger, so how do professional and health-centered industries tackle this issue? First of all, people directly coming into contact with machinery are obliged to wear specialized chem-protecting clothing, aprons, or encapsulated suits. This solves the issue of people coming into contact with the machines directly, however, to remove the oil mist we need to use what is called mist collectors that capture the oil mist and filter out the dangerous microscopic particles. Today there are basically three main types of oil mist collectors used in the industry.
1. Electrostatic Precipitator Mist Collectors
An electrostatic precipitator uses high-voltage electricity to impart a positive charge onto the particles of mist carried by an air current. Then, the air is passed between a series of negatively-charged plates, and the positive charge in the mist particles is attracted to the negative charge on the plates. The particles, still being oils, stick to the plates once they hit and are removed from the airflow.
2. Spiral Oil Mist Collectors
A spiral tube oil mist collector works by forcing the air through a vertical tube in a downward spiral, then upward through the center of that same spiral. Particulates drop out of the airstream at the bottom of the spiral. The process of running the air is made through several — sometimes dozens — of tubes to make sure that a sufficient percentage of the particulate is removed, and then the air is passed through a HEPA filter to guarantee adherence to air quality regulations. Because the air passing through the filter is already mostly clean, the filters on these collectors last much longer than the filters on an entirely filter-based collector.
3. Centrifugal Mist Collectors
These are the most advanced and most effective class of such filters. Actually, the first modern use for these types of filters was in the gearboxes of nuclear submarines. As the name implies, centrifugal oil mist collectors from 3nine consist of a circular, rotating filter that spins all of the air inside. The heavier particles are pushed back into the filter while the lighter particles — clean air — escape through a hole in the top. The oils then pass through the filter and onto the inside of a drum, where the spinning air propels it along the inside surface of the drum until it reaches a drain, where it can be collected for reuse or disposed of.