“Stainless Steel Worm Gear” Is Not the Same as Food Grade

NSF H1 lubricants are formulated for applications where incidental contact with food product is possible. They use food-approved base oils and additive packages. NSF H2 lubricants are for non-food-contact surfaces only — they may contain additives that are not approved for food contact. For any worm gear drive in HACCP Zone 1 or Zone 2 — which includes most conveyor drives, portioning drives, filling drives, and agitator drives in food production areas — specify NSF H1. If there is any doubt about whether a drive position is Zone 2 or Zone 3, default to H1. The cost difference between H1 and H2 lubricants is small; the cost of a food safety non-conformance is not.

Tin bronze worm wheels are acceptable in HACCP Zone 2 (splash zone) food processing applications when the wheel flanks are electropolished to Ra ≤ 0.8 µm and the drive is adequately sealed against product ingress. In Zone 2, the risk is surface bacterial adhesion, not product contact — and a properly electropolished bronze surface provides adequate resistance. The case for bronze over stainless steel in Zone 2 is the tribological advantage: bronze provides better anti-scuffing performance at the sliding contact velocities typical of food machinery drives (1–6 m/s), particularly when using NSF H1 lubricants that lack EP additives. For Zone 1 direct product contact, the wheel must be SS316 or another FDA-acceptable material.

Three elements require attention for sub-zero operation. First, lubricant: ISO VG 460 mineral oil at −20°C reaches viscosities of 4,000–8,000 cSt, causing severe viscous drag and motor overcurrent. Specify NSF H1 synthetic PAO ISO VG 100 or 150, which maintains approximately 300–500 cSt at −20°C. Second, seal material: standard NBR seals become brittle below −20°C; specify FKM (Viton) or silicone seals. Third, housing material: standard ductile iron housings are acceptable to −30°C; below −30°C, specify ferritic stainless steel or aluminium housing to avoid brittle fracture risk.

Yes. PPAP Level 1 (Part Submission Warrant), Level 2 (PSW + limited supporting documentation), and Level 3 (PSW + full supporting documentation) are available for established supply programs. Confirm the required PPAP level at order placement — Level 3 requires additional production documentation lead time and should be agreed in the initial order confirmation. PPAP is not available on first-order prototype or sample quantities; it is available for production supply programs after sample approval.

SS316 is compatible with: sodium hydroxide (NaOH) at up to 4% concentration, 80°C; phosphoric acid (H3PO4) at up to 2%, 60°C; nitric acid (HNO3) at up to 2%, 60°C; peracetic acid (PAA) at up to 0.3%, 40°C; and chlorinated alkaline CIP agents at up to 200 ppm active chlorine, 50°C. Avoid CIP solutions containing hydrochloric acid (HCl) — this will cause rapid pitting corrosion on all grades of stainless steel.

For equipment in Zone 1 and Zone 2, yes. Your HACCP documentation should include a list of all materials in contact with or adjacent to food product, including drive train materials and lubricants. The documentation package from Korea Ever-Power (material certificate, lubricant compatibility confirmation, surface finish report) provides the information needed for this disclosure. If your facility undergoes IFS, BRC, or SQF certification in addition to HACCP, additional disclosure requirements may apply.

The material specification (SS316, Ra ≤ 0.4 µm electropolished) is the same. The documentation requirements differ. Food processing facilities typically require NSF/FDA compliance documentation. Pharmaceutical manufacturing facilities under GMP regulations require additional documentation: ISO 10993-1 biocompatibility grouping, material traceability to starting stock, and PPAP or equivalent qualification documentation. Korea Ever-Power can provide the standard food-grade documentation package for food applications and the extended pharmaceutical package for GMP applications — confirm which documentation standard applies at order placement.

NSF H1 PAO synthetic gear oils have extended drain intervals compared to mineral oils — typically 3,000–4,000 operating hours for enclosed drives at normal operating temperatures. For food processing applications where the housing temperature remains below 60°C, an annual oil change (or every 2,000 hours, whichever comes first) is appropriate. The first oil change after any gear replacement or new installation should be at 50–100 operating hours to remove running-in bronze wear particles. Use only NSF H1 certified lubricants for top-up — mixing H1 and H2 lubricants in a Zone 1 or Zone 2 drive invalidates the H1 compliance of the entire fill.