Filter fineness in extrusion is always defined in microns (µm) — but screen packs are still specified in mesh count. This page gives you the complete mesh-to-micron conversion chart, an interactive calculator, and practical guidance on selecting filtration fineness for your specific extrusion application.
Mesh count is the number of wires per linear inch in a woven metal screen. A 100 mesh screen has 100 wires per inch; a 325 mesh screen has 325. The more wires per inch, the smaller the opening — and the finer the filtration.
Micron (µm) is the actual opening size between wires, measured in thousandths of a millimeter. A 100 mesh screen has an opening of approximately 150 µm; a 325 mesh screen narrows to roughly 44 µm.
The relationship between mesh and micron is not linear. It depends on wire diameter and weave type. The values in the conversion chart below follow ASTM E11 (Standard Specification for Woven Wire Test Sieve Cloth) and ISO 3310-1 (Test Sieves), which are the two dominant standards used across the extrusion industry.
“Specifying only mesh count without stating wire diameter or weave standard leaves room for significant variation between suppliers. Always cross-reference with micron opening.” — Process engineer, European film extrusion line
| Mesh Count | Micron Opening (µm) | Typical Application in Extrusion |
|---|---|---|
| 20 | 850 | Pre-filtration, heavy contamination, scrap recycling |
| 30 | 600 | High-contamination recycling, post-consumer streams |
| 40 | 425 | Post-industrial recycling, general compounding |
| 50 | 300 | Compounding, masterbatch, pipe extrusion |
| 60 | 250 | Pipe, sheet, general purpose |
| 80 | 180 | Blown film (PE/PP), extrusion coating |
| 100 | 150 | Film extrusion, wire & cable insulation |
| 120 | 125 | Blown film, stretch film |
| 150 | 106 | Cast film, stretch film, fiber |
| 200 | 75 | Fiber spinning, nonwoven (spunbond) |
| 230 | 63 | Fine filtration, fibers, technical film |
| 270 | 53 | BOPP film, technical film |
| 325 | 44 | Fine filtration, BOPET film, high-clarity film |
| 400 | 38 | Ultra-fine, optical film, specialty fibers |
| 500 | 25 | PET fiber, bottle-to-fiber applications |
| 635 | 20 | Fine filtration limit for most screen changers |
Values based on ASTM E11 and ISO 3310-1. Opening size may vary ±5% depending on wire diameter and weave construction.
Enter a mesh count, a micron value, millimetres, or inches — the converter calculates the equivalent and highlights the nearest standard screen size.
| Mesh # | µm | mm | inches |
|---|
Choosing the wrong filtration fineness has a direct cost. Too coarse, and contaminants pass through, causing gel defects, surface imperfections, and spinneret blockages. Too fine, and pressure builds too fast, causing frequent screen changes, downtime, and process instability.
According to AMI Consulting’s extrusion equipment market data, melt filtration-related downtime accounts for 10–30% of unplanned production stops in continuous extrusion lines. For a line running at 800 kg/h, a single 20-minute screen change means 267 kg of lost output — and if it happens three times per shift, that is over 800 kg per shift.
The right filtration fineness minimizes both defect risk and screen change frequency simultaneously.
Use our Productivity Savings Calculator to quantify the production and cost impact of your current filtration setup — and see the difference a continuous screen changer makes.
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