- December 11, 2019
By Mark Howard, EU Automation
It is vital to understand how cleanrooms truly operate if you are to get the best out of yours. This article explains the key considerations when specifying a cleanroom.
By Mark Howard, North America country manager, EU Automation
The traditional family photo album is dying out in the digital era. Though the same cannot be said for cameras ‚Äï or the cleanrooms where their lenses are made ‚Äï as we are taking more photos than ever before. Funnily enough, it isn’t our families we are photographing more, but ourselves ‚Äï one third of images are now selfies. This article explains the key considerations when specifying a cleanroom.
In a cleanroom, particle contamination is carefully controlled, as are other environmental factors. They are commonly used for the manufacturing of semi-conductors, optics, biotechnology and prescription drugs, as well as any other application where particle contamination can have negative consequences. Cleanrooms are designed and operated in a manner that eases the management of the introduction and generation of particles among the atmosphere.
All cleanrooms are classified by the quantity of contaminants that exist per cubic metre. The International Standards Organisation (ISO) standards vary from Class 1 to Class 9 — the lower the ISO category rating, the cleaner the environment. For instance, ISO category 5 cleanrooms can contain a maximum of 3,520 particles per cubic metre. This means that it cannot have over 3,520 particles bigger than 0.5 microns in size. To put the size into perspective, a person's hair is 75 microns.
Let’s glance at some examples. Medical device cleanrooms are usually designed to the classifications ISO category 7 or ISO category 8; the cleanroom atmosphere attempting to eliminate surface contamination or viable particulate on the merchandise. On the opposite end, nanotech and electronics cleanrooms vary from ISO category 1 to ISO category 6 due to temperature and moisture, as well as particulates and static having the ability to directly impact the finished product.
It is vital to understand how cleanrooms truly operate if you are to get the best out of yours. The bulk of cleanrooms exist on a positive pressure technique — air is pumped into the space using high-powered high-efficiency particulate air (HEPA) filters that take away the mandatory contaminants, then push the air out through vents in the floor. As a result, positive pressure cleanrooms have higher atmospheric pressure than the rooms close to them. The pressure difference means that air flows from the cleanroom into other rooms, forcing contaminated air away from the cleanroom.
Cleanroom systems place the very highest demands on hygiene and method safety. Most contamination among cleanroom facilities is traced back to humans, thanks to the natural shedding of high numbers of skin cells into the air. This has vital implications for cleanrooms, as we are a supply of contamination, harbouring over thirty million bacteria on our bodies. To make matters worse, we also act as an agent for transferring contamination to locations that might create a product risk — spreading microorganisms by coughing, sneezing and touching. Any person entering the cleanroom should wear specialised cleanroom garments and the necessary personal protective equipment (PPE).
Some cleanroom classifications necessitate the installation of automatic systems — the lower the classification number, the more likely that the procedures within the cleanroom must be executed as automatically as possible. There are numerous benefits to automating processes. Apart from the obvious decrease in particle emissions, automation can guarantee absolute system security and marginal air leakages, as well as being straightforward to clean and made from wear-resistant materials.
Choosing the correct automation equipment for a cleanroom application depends entirely on the strictness of the atmosphere, along with the classification of the equipment itself. Equipment can be certified as acceptable for various cleanroom environments according to the quantity of particles they generate, once in motion.
Specialised cleanroom instruments boast a highly sealed structure, guaranteeing essential levels of cleanliness for cleanroom applications. They may also be minimised crevices in machines and guaranteed resistance to cleaning and sterilising agents. Dependent on the classification of the cleanroom, automated solutions may be upgraded to full dust emission, no grease release and closed, protected cables.
Component selection in the design or upgrade of any machinery is a vital factor in ensuring the machine complies with the requirements of the cleanroom. In cleanroom applications, it is best to choose components that exhibit little or no fibre shredding —
brushless motors and enclosed slip rings are both obvious candidates. Furthermore, the type and grade of drive belts and the general drive train can have a massive impact on the suitability of the machine for the cleanroom.
There are a number of ways to keep equipment costs to a minimum in a cleanroom. One common pitfall that designers could fall in is over specifying machinery and components. For example, choosing ISO 1 standard components, suitable for nanotechnology or ultra-fine particulate processing, to be used in a cleanroom that has a classification of ISO 5. Not only will this greatly narrow the cleanroom automation options, it is also a very costly option with no real added benefit.
It is important that your cleanroom fits the requirements of the application. Meeting the standard of the designated ISO classification requires a great deal of understanding about processes and policies. Another crucial factor is the investment in high-quality equipment, containing components that are cleanroom-safe. After all, the right cleanroom environment allows optics technicians to create lenses that allow us to capture the timeless smiles of, well, ourselves.Learn More
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