Today, our cleanroom series is focusing on production-free periods and what this means for maintaining a cleanroom. Because even when production is not taking place, the cleanroom must be operated in accordance with all requirements. This is because there is always positive pressure in a cleanroom, which prevents particles from entering. If the ventilation technology and therefore the positive pressure were to be removed during non-production times, the cleanroom would gradually become contaminated and lose its hygiene status. If production were to begin again, the cleanroom would have to be re-qualified and re-certified after cleaning and disinfection.
Filter maintenance is paramount
This procedure would be much more complex and expensive than ensuring cleanroom status on an ongoing basis. But what does this require? Most importantly, the ventilation system must be kept in operation and the maintenance intervals for the main and pre-filters must be observed. Pre-filters are used to protect the main filters and keep them in good condition for longer. Not least for economic reasons, it is therefore advisable to replace the pre-filters more frequently. If the pre-filters are replaced approximately every six months, the main filter can be used for up to eight years. Crucially, the predictive maintenance concept ensures that contamination is detected at an early stage and filters are replaced accordingly. By the same token, filters are also left in use if they are not yet dirty when they are routinely checked.
Shell principle for small cleanroom areas
Production at RKT is structured according to the shell principle, which is crucial for maintaining a cleanroom outside of production times. Around 70 percent of production already takes place under clean ISO 8 conditions, while specific areas, which are significantly smaller in terms of space, are enclosed for ISO 7 or GMP C purposes and equipped with the appropriate ventilation technology. The smaller a cleanroom is, the lower the maintenance costs of filter maintenance, energy, and electricity. This means that all processes that do not require a cleanroom can run outside the ISO 7 production cells. For example, the injection molding machines are usually located outside the cleanroom in the ISO 8 area and produce parts into the cleanroom, where robots remove them from the injection molding machine and process them further. In addition to the amount of space that this makes available, the hygiene aspect is also important here, as potentially dirty maintenance work on the injection molding machine is better conducted outside. This also means that technicians do not have to pass through the lock with the necessary equipment.
Maintaining cleanroom status
If an ISO 7 cleanroom is used again for a new project, it retains its status and the necessary process adjustments can be made for the product in question. Each component is subject to specific conditions, from temperature and humidity control to the sequence of process steps. In an existing ISO 7 setting, however, the individual parameters are much easier and more economical to implement than having to requalify the cleanroom.
