Warehouse cage load ratings are generally divided into three grades—light, medium and heavy—based on the rated load of a single cage, and picking the right grade is what balances safety, cost and stacking levels. For cages with the same overall dimensions, a different load grade can double the amount of material used and widen the price gap accordingly.
Light-duty cages typically carry a rated load of 300~500kg, with a wire diameter of 3.5~4mm and 20×20 square-tube posts; they suit cartons, bagged materials and light hardware parts and can be stacked 2 high. Medium-duty cages carry 500~1000kg, with a wire diameter of 4.5~5mm and 25~30 square-tube posts; this is the most common grade for workshop turnover and can be stacked 3 high.
Heavy-duty cages carry a rated load of 1000~2000kg or even more, with wire diameters above 6mm, reinforced 40×40 square-tube posts and ribbed base plates; they suit casting blanks, stamping parts and full-pallet loads. They must be fitted with stacking feet and are limited to 2 stacking levels. Heavy-duty cages are themselves heavy, weighing 80~120kg each.
Do not choose the grade by average cargo weight alone; calculate margin based on the heaviest single fully loaded unit. Operating at 80% of the rated load is the safety line, while sustained loading above 90% accelerates weld cracking and post deformation. After loading, also watch the center of gravity: with off-center loads, the effective capacity must be discounted further.
Selection tip: tell the manufacturer the heaviest single-unit weight, the number of stacking levels and the frequency of use. Since its founding in 2013, Nanjing Tongnuo Warehouse Equipment Manufacturing Co., Ltd. has produced standardized light/medium/heavy grades, and also supports non-standard customization based on measured loads.