Cleanroom or CNC Cleanroom: why the decision is so important
Both cleanrooms and CNC Cleanrooms have the same goal: to protect products and manufacturing processes from contamination by particles. Both room types control the air quality and work with filtered air, regulated air flows and defined access conditions. In terms of basic design, they often look very similar – similar wall systems, similar ceilings, similar airlock concepts.
This is precisely what leads to confusion in practice: depending on the technical implementation, a CNC Cleanroom can certainly reach the level of an ISO class 9 or 8 cleanroom. However, this is not a must, but a question of design.
The decisive difference: the particle size
The key difference lies not in the appearance of the room, but in the particles that need to be controlled – and this concerns both the size and the behavior of these particles in the air.
In the cleanroom, the focus is on invisible, airborne particles. ISO standard 14644-1 specifies the maximum number of particles of a defined size (between 0.1 and 5.0 micrometers) that may be present per cubic meter of air. For comparison: a human hair is around 70 micrometers thick – the relevant cleanroom particles are therefore significantly smaller than what the human eye can perceive. They float in the air and do not settle on their own. They can only be removed from the room by high air exchange rates and high-performance HEPA or ULPA filters.
The CNC Cleanroom , on the other hand, is all about visible particles – typically between 100 and 600 micrometers in size. These are dust, fibers, fluff, hair or metal shavings. These particles are visible to the naked eye (from approx. 40 micrometers) and – depending on their density – sink onto surfaces. They remain there until they are actively removed. Air exchange alone is of little help here. Behavior, clothing and cleaning processes therefore play the more important role in the CNC Cleanroom.
Pictorial comparison: The size ratio between a cleanroom particle and a CNC Cleanroom particle is roughly equivalent to the ratio of a VW bus to a soccer pitch. Cleanroom particles are tiny – cleanroom particles, on the other hand, are much larger and more tangible.
Cleanroom: certified according to ISO 14644-1
A cleanroom is defined according to the international standard DIN EN ISO 14644-1 standard. This defines nine ISO classes (1 to 9) – the lower the number, the cleaner the room. Typical areas of application are microelectronics, semiconductor production, pharmaceuticals, biotechnology, medical technology and aerospace. In these industries, contamination with tiny particles can render a product worthless.
The technical requirements are correspondingly high: air exchange rates of 20 to 500 times per hour, HEPA 14 or ULPA 15 filters, mandatory personnel and material pass-trhoughs, defined cleanroom clothing and ongoing monitoring. All of this is reflected in the costs: 1,000 to 5,000 euros per square meter are realistic investment costs.
CNC Cleanroom: flexible, efficient, process-oriented
A CNC Cleanroom – also known as a “Clean not Certified” – has no universally applicable standard. In Germany, the requirements are usually based on the VDA 19 (international: ISO 16232). The specific cleanliness specifications often come directly from the customer or their clients.
Typical areas of application are the automotive industry, precision mechanics, optics or general mechanical engineering production. Here it is visible particles – metal chips, dust, fibers – that cause rejects or block supply chains. The air exchange rate is around 10 changes per hour, and simpler fine dust filters are used. The investment costs are typically between 1,000 and 1,500 euros per square meter.
Cleanroom vs. CNC Cleanroom: a direct comparison
For a quick orientation, we have summarized the most important differences:
| Cleanroom | CNC Cleanroom |
Particle size | up to a maximum of 5 micrometers | up to 600 micrometers (process defined, also larger) |
Particle type to be removed | Airborne particles by size | Process defined (e.g. metal particles) |
Measurement | Airborne particles | Particles on components |
Measuring method | Particle counter | Washing tests and optical methods (residual dirt analysis) |
Standard | DIN EN ISO 14644-1 | VDA 19 (international: ISO 16232) |
Classes / levels | ISO class 9 to 1 | Cleanliness levels 0-3 |
Air exchange rate | 20-500 air changes/h (depending on cleanroom class) | up to approx. 10 air changes/h |
Filter | ULPA 15 / HEPA 14 (high-performance HEPA filter) | Particulate matter or fine dust filter |
Personnel and material pass-trhoughs | Mandatory | Recommended |
Area of application | High purity or sterility required | Visual cleanliness required |
Acquisition costs | 1.000-5.000 €/m² | 1.000-1.500 €/m² |
Operating costs | High | Moderate |
Which solution do you really need?
The key question is: what particle size will damage your product? If microscopic, invisible particles under 5 micrometers are a problem, you need a certified cleanroom. If, on the other hand, visible contaminants such as dust, fibers or chips are a problem, a CNC Cleanroom is the more economically viable and technically sufficient solution.
In practice, we often observe that customers buy a cleanroom even though a CNC Cleanroom would be perfectly adequate – or, conversely, that they start with a simple cleanroom that does not meet their process requirements. This is precisely where our consulting services at Schilling Engineering come in: we help you to find the right room solution for your specific requirements – neither oversized nor undersized.
Conclusion
Cleanrooms and CNC Cleanrooms basically solve the same problem – uncontrolled particles in production. The difference lies in the detail: Cleanrooms control invisible, airborne microparticles according to an international standard. CNC Cleanrooms control visible, sedimenting particles according to process-defined requirements. The technology is often similar – but the effort, costs and requirements differ considerably.
Talk to us about your process – we will evaluate neutrally whether a cleanroom or a CNC Cleanroom makes technical and economic sense.
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