Perforated metal in food processing facilities does more than move product from one stage to the next. It is a hygiene surface. The material choice, surface finish, hole geometry, and edge treatment all affect how cleanly and reliably the screen performs in regulated production environments. Specifying the wrong grade or finish can lead to corrosion, contamination risk, and costly equipment replacement at a time when the facility may have product liability and regulatory exposure on the line.

Grade selection for the processing environment

304 stainless is the standard specification for most general food processing applications. It is food-grade under United States Food and Drug Administration regulations, European Union Regulation 1935/2004, and Canadian Food Inspection Agency guidance. Dairy processors use 304 for conveyor screens, drainage panels, and sorting equipment in most of their production areas. Bakeries use 304 perforated sheet for baking trays, cooling racks, and ingredient separation screens throughout production lines that operate in dry to moderately humid environments.

316 stainless is the appropriate specification when the processing environment involves chlorinated sanitizers, salt brines, acidic marinades, or frequent high-pressure washdown. Seafood processors, meat packing facilities, and pickle and sauce manufacturers use 316 for exactly this reason. Clean-in-place systems that cycle concentrated cleaning chemicals and high-temperature rinses through the same surfaces multiple times per day will eventually pit 304 surfaces through chloride attack. The same surfaces in 316 resist that degradation because of the molybdenum content that stabilizes the passive oxide layer against chloride penetration.

Surface finish affects hygiene as much as alloy selection does. Mill finish is acceptable for most non-contact surfaces. Direct product contact surfaces are typically specified with a 2B finish or smoother, as finer surfaces reduce microbial adhesion and make cleaning more effective. The 3-A Sanitary Standards that govern dairy and food processing equipment design in North America specify surface finish requirements alongside material grade. Equipment fabricators building to those standards should confirm finish requirements with their supplier at the request for quotation stage.

Hole geometry and edge treatment

Hole size in food processing screens is determined by the product being handled. Fine separation screens for grain milling, spice processing, and powdered ingredient handling use very small round holes, often in the 1 to 3 millimetre range. Conveyor decking and drainage trays use larger holes, typically 5 to 12 millimetres, where the goal is to drain liquid or allow air circulation rather than separate particles. Seafood and meat processing screens that support product weight while allowing drainage often use round holes in the 6 to 10 millimetre range in 16 or 14 gauge 316 stainless.

Burr-free edges are a common requirement for food contact surfaces. Perforating creates a small burr on the exit side of each hole, and in food equipment that burr must be removed to eliminate product lodging points and cleaning obstacles. Specify deburring or edge treatment in your request for quotation when the material will be used in direct product contact applications. Canada Perforating supplies mill test reports and certificates of conformance for all stainless material on request, which food equipment fabricators typically require for regulatory compliance documentation.