COVER STORY
Your cleanroom meets spec, so why are there still particles on your product?
Why laminar flow hoods can’t solve everything, and what can Y
ou’ve done everything right. Your laminar flow hood or clean workbench is qualified, the HEPA filters are in date, and
the airflow is on target. Yet under the inspection lamp, there they are again: tiny fibres and specks on a catheter, a syringe barrel or a blister tray, on parts that were clean a moment ago. If that sounds familiar, you’re not alone. Many medical device manufacturers keep finding particle contamination, and paying for the rework, even when their cleanroom conditions meet specification.
THE CULPRIT YOU CAN’T SEE In many of these cases, the cause isn’t your air at all. It’s electrostatic attraction (ESA). Many medical devices are made from
polycarbonate, polypropylene, polyethylene, ABS or PEEK. These plastics are electrical insulators, which also makes them very good at holding on to static charge. Every time a tray is handled, a protective film is peeled off, or a part is picked, placed and pressed, static charge builds up on the surface resulting in attraction of particles. Think of a charged balloon picking up dust. A laminar flow hood removes airborne particles. It does not neutralise static charge. So, a charged plastic part sits in perfectly clean air and still attracts particles. Airflow alone cannot fix that. It follows you through the whole process ESA travels with the product from the first tray to the final pack: 1. Preparation: material transfer, tray handling and protective film removal generate charge before assembly has even begun
2. Assembly: pick-and-place bonding, fastening and operator handling add more charge, and particle contamination leads to assembly defects
3. Verification: visual inspection and functional testing lead to extra cleaning, inspection and rework
4. Packaging: packaging materials and final handling can recontaminate a product just before it ships
Sound like a typical week on your line? Then you
probably also know the follow-on effects: extra inspection steps, troubleshooting sessions that stop production, and customer returns that turn into quality investigations.
IS STATIC YOUR PROBLEM? Static problems are easy to misdiagnose as a filter, cleaning, material or operator issue. A few clues point towards static instead: • Particles keep appearing on plastic parts, even though your hood or workbench is qualified and the airflow is on target
• Parts are contaminated again shortly after handling, tray transfer or removal of a protective film
• The problem gets worse when the air is dry. Insulating materials hold on to more charge at low relative humidity (below 30 per cent). Raising the humidity is not a reliable fix, though: unacceptable charge levels can still build up and persist at high humidity
You don’t have to guess. Static charge can’t be seen, but it can be measured. A handheld electrostatic fieldmeter such as the Simco- Ion FMX-004 shows the charge on a surface in kilovolts, and its polarity, up to 30 kV at a measuring distance of 25 mm. Measuring is the first step in controlling static: it shows where charge is generated and later lets you check that your solution is working.
WHAT IT COSTS Take a manufacturer assembling 5 million plastic catheters a year, at €3.50 per finished unit. In this example, contamination costs roughly €400,000 a
Challenge
Scrap from contamination defects Rework and additional inspection
Production downtime and troubleshooting Customer returns and quality investigations Estimated annual impact
10 September/October 2026 Irish Manufacturing
year: These figures are for illustration only. Your
numbers will differ with production volume, product complexity and quality requirements. But most quality and production managers can plug in their own figures and see the pattern.
SOLVING IT AT THE SOURCE At Simco-Ion, we don’t try to clean up the consequences. We go to the root cause. Ionisation equipment produces positive and negative ions: a negatively charged part attracts positive ions, a positively charged part attracts negative ions, and the charge is neutralised. Once the charge is gone, the part no longer pulls particles towards it, and contamination is prevented before it happens. Three products from our European range are
Operational impact 25,000 units (0.5 per cent) 50,000 units (1.0 per cent) 200 hours
40 investigations
Estimated annual cost €87,500 €133,000 €107,500 €72,000 €400,000
www.irish-manufacturing.com
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