Pot Magnet Holding Force Estimator

This is a rule-of-thumb estimator, not a substitute for a tested rating. It starts from a theoretical bare-magnet direct-contact pull force (Br²·A/2μ₀ with a ~55% practical-efficiency factor), applies a pot-assembly concentration multiplier (typically 2–4× a bare magnet of the same size, depending on cup design — genuinely variable across manufacturers), then derates for air gap, surface condition, and pull direction (shear ≈33% of direct pull-off for pot magnets, per published industry figures). Real holding force depends heavily on the specific cup geometry, steel grade, and wall thickness — always confirm against a manufacturer-tested rating for anything load-bearing or safety-relevant.