Properly Equipped Cleanrooms
Air-flow, layout, and flooring are the major components that that allow cleanrooms to function according to specifications, and standards of class. But there is more to keeping a cleanroom clean. As much time and careful consideration that goes into the planning and development of these critical aspects, should also be applied to the selection, engineering, and integration of cleanroom equipment. Engineers must design equipment and mechanical components that comply with industry standards in regard to the number and size of particles that these machines generate.
First, it is important to note that there are both active and passive means of particle generation. Active particle generation happens mostly from friction, which commonly occurs with linear-bearing blocks and ball screws. A way to minimize this friction is to use seals made of virgin Teflon or unfilled urethanes as these resist abrasion and thus produce fewer particles. Lubricants can also be a source of airborne contamination, but there are inexpensive, low migration greases that can be used to diminish this kind of particle generation. Passive particle generation occurs when surfaces shed particles. In this case, stainless steel is better than plated or oxide-coated steel. It is also recommended that surfaces contain as few joints, cracks and irregularities as possible. This ensures that particles are not being trapped on surfaces where they can build up and eventually pollute the air.
Some devices and equipment are apt to produce more particles than others no matter how well they are engineered. To accommodate for this, these devices should be placed as close to the floor or ducts as possible, so that excess particles are carried away by the airflow. Another option would be to apply a vacuum or negative pressure to these areas and pieces of equipment in order to remove particles. When it comes to constructing a cleanroom that is successful, the design and incorporation of the equipment used is just as important as the components that make up the cleanroom itself.