For some applications, it is important that certain componentents has been made in a very clean and controlled environment. This is particurlaly important in the biotech, electronic, food and pharmaceutical industries. The production is usually quite large volumes.
Clean room are defined by optical measurements of small air particles, and there are different limitations for different degrees of cleanliness. This classification is determined by a standard named ISO 14644, which basically set limits for the number of and size of airborne particles on a scale from one to nine. Every increasing step on the scale means the particles tenfolds.
There is much that can be done in addition to ordinary air cleaning. Common, for example, is to have a special interior, protective clothing and controlled humidity. The actual moulding is similar in clean rooms to the traditional molding processes in workshops. A mold is made and clamped, after which molten plastic is pushed into the tool that is cooled. As the plastic solidifies and the component is complete. See for example injection molding for more information.
Picture: Maxell Moulding Services