Congratulations on your recent article, “Cleaning up automotive manufacturing” in Cleanrooms magazine (October, pg. 12).

As a cleanroom HVAC professional in the Detroit metropolitan area who has been designing semiconductor, pharmaceutical as well as automotive facilities for the last 18 years, I fully agree with the cases you revealed concerning the contamination control progress in automotive manufacturing.

As you noted, many “cleanroom” applications in automotive manufacturing facilities don't adhere to the ISO classifications. A majority of critical spaces, such as transmission, fuel injector assembly and spray-paint booths were not initially designed as certified “cleanrooms,” but rather as non-classified “cleaner rooms.” Automotive facilities engineers, however, are increasingly aware of the need to make cleaner manufacturing-and the trend toward more stringent control is accelerating.

German automotive supplier Siemens utilized Class 10,000 for its fuel injector assembly facilities more than a decade ago. Eight years ago, I served as a cleanroom consultant to design an overseas fuel injector assembly facility at a Class 10,000 facility for Ford-its design concept was much closer to a typical semiconductor facility rather than a traditional automotive manufacturing line.

We conducted air sampling in some existing automotive “cleanroom” spaces and found that the contaminant particle sizes were quite large-often 50 µm and larger. These particles were mainly due to poor pressurization and lack of airlocks and pass-throughs, as well as the lack of pre-cleaning treatments to equipment, personnel and parts. We found that cleanroom classifications could be achieved after we applied the following measures:

• Pre-cleaned equipment, personnel and parts prior to entrance into the critical rooms;
• Sealed enclosures with controlled multistage pressurizations, temperature and humidity;
• HEPA filtration;
• Process enhancement to reduce particle/sediment generations;
• Protective garments;
• Cleaning;
• Double-door arrangement separating the adjacent spaces, including shipping/receiving area.

It is feasible to have critical spaces designed as classified cleanrooms. As one engineer in your article indicated, “Over the next decade, we will migrate toward the semiconductor manufacturing model and away from the heavy steel industry.”

Wei Sun, P.E.
Principal, Chief Mechanical Engineer
Engsysco Consulting Engineers
[email protected]