Material and Surface Finish for Food-Grade Wedge Wire Screens

Stainless steel 316L is the standard material for food-grade wedge wire screens, but surface finish matters as much as the alloy. 316L provides the corrosion resistance needed for repeated CIP (Clean-in-Place) chemical exposure. V-wire geometry eliminates crevices and dead zones that trap product residue. Every weld is a fused resistance weld with no filler metal, solder, or adhesive, so the unit is a single homogeneous stainless steel piece. Surface finish determines cleanability and bacterial resistance. For dairy, beverage, and pharmaceutical applications, specify electropolished finish at Ra 0.8 micrometers or better. Electropolishing removes the disturbed metal layer and creates a chromium-enriched passive surface that resists bacterial adhesion and cleans faster than mechanically polished surfaces. For less demanding food applications (grain, sugar, starch), a standard pickled and passivated finish is sufficient. Regulatory compliance in food processing is demonstrated through material conformity, surface finish specification, and fabrication practice. The relevant frameworks include 3-A Sanitary Standards, EHEDG (European Hygienic Engineering and Design Group) guidelines, FDA 21 CFR 174-186 for contact surfaces in the US, and EC 1935/2004 in the EU. ADEN provides test reports and certificates of conformity that document compliance with these requirements. Design considerations: avoid horizontal surfaces where product can pool, ensure all internal angles are radiused (no sharp corners), and verify that the unit can be fully cleaned in place without disassembly. Wire orientation should allow drainage during cleaning cycles.