Some industries must work under ‘clean’ conditions because even the smallest particles or outgassing can destroy an entire product batch. So what exactly does cleanliness suitability mean? How is it measured and determined? Would production under ‘’pure‘’ conditions also be a decisive competitive factor for your company? We will get answers to these questions for you in this blog article.
What exactly is meant by the term cleanliness suitability? Cleanliness suitability is regulated in VDI Guideline VDI 2083, Sheet 9.1 ‘Cleanroom technology – Compatibility with required cleanliness and surface cleanliness’ and is defined as follows:
“The compatibility with the required cleanliness [is the] criterion for the assessment of pieces of equipment or air-handling components in view of their use in cleanrooms (Note: The compatibility with the required cleanliness describes the generation or existence of the contamination generated by, or existing on, the piece of equipment or air-handling component.)" – VDI-Guideline 2083, Part 9.1 Chapter 3.1.3
However, a universal definition set in stone does not do justice to this complex topic. The best way to illustrate cleanliness suitability is to differentiate it from another requirement, namely cleanroom suitability.
Cleanroom suitability describes the emission of contamination of an operating device to the surrounding cleanroom. Cleanliness suitability is the release of particles onto the product that is processed in the machine. The following graph explains the procedure for determining the respective suitability:
Source: VDI 2083 Part 9.1 Page 7 Picture 3
Cleanroom suitability is a part of cleanliness suitability and is not necessarily important for the actual process. Cleanroom suitability is only important if you want to know how many machines are allowed to work in a cleanroom without affecting the classification and if cross-contamination must be prevented.
The local measurement method is considered as the proven measurement method for determining cleanliness suitability. The particle concentration in the air is measured at various points on the test object. With the value determined in particles per cubic metre, this measurement object can be assigned a classification number from ISO 1 to 9 using the ISO 14644 classification. However, it should be noted at this point that a component or a machine cannot be assigned to an air cleanliness class. The categorisation in the ISO 14644 classification only states that no more particles were measured at any point than ... and this determined value, mirrored in the classification, results in the respective classification number ISO 1 to 9.
The VDI guideline is definitely a good approach that promises to be binding and reliable. However, it has a limit: unfortunately, it only deals with the holistic method as a measurement method in passing.
A description of the total particle emission per unit of time is possible using the holistic method. However, this method is not used for direct classification, which means that it can no longer be categorised into classes. This means that on the result sheet we read particles per second and not ISO 1, 2, 3 etc.
If the holistic method cannot provide a classification of components in specific purity classes, what advantage does it have?
Equipment can be compared with absolute precision using the holistic method. Whether a laptop, a car or a production line – it is possible to say how many particles are emitted per second from all components in their entirety.
How are the measurements carried out using the holistic method? The measurement object is surrounded by ultrapure air and the particle concentration is measured in the exhaust air as with the localised method. In addition, the volume flow of this exhaust air is determined. If the particle concentration in particles per cubic metre is multiplied by the volume flow in cubic metres per second, a particle flow in particles per second is obtained.
Cleanliness suitability is elementary for all those who use machines or components in clean production.
The example of the automotive industry makes it clear how important a clean production environment is in the most diverse work steps: from the paint and lighting to the headlights and lenses to the complete interior – cleanroom technology plays an important role in the production process everywhere.
The most important impulses for the application of measures for cleanliness suitability are:
So it's not just about ensuring functionality, quality and aesthetics, i.e. aspects that are quite obvious. It is also about demonstrating expertise by dealing with this important topic as a company and thus possibly having a major knowledge advantage over the competition. Whether you buy this expertise in or implement it directly in-house only plays a subordinate role.
Risk management, added value and return on investment are important keywords for every company. The more complex and multi-component a process is, the more important detailed monitoring is to ensure that weak points or blockages can be detected and eliminated as early as possible or even eliminated in advance. Those who ensure quality assurance along the entire process chain are guaranteed smooth production processes, few rejects and only short downtimes. If machines, materials and components are suitable for cleanliness, many obstacles to clean, consistent production are eliminated from the outset.
Cleanliness suitability is a characteristic of quality, innovation and cost assurance. Positive results in this area should therefore not be left to lie dormant in a drawer, but should definitely be communicated to customers and interested parties!
This aspect relates back to the competitiveness mentioned above. If a company decides to have its machines and components tested for cleanliness, it is essential that a member of the marketing team is involved in this decision-making process.
Get the free whitepaper ‘Ways to ensure cleanliness suitability’ and find out more about cleanliness suitability and why you should look beyond the limits of a cleanroom.