The load capacity of a steel material box is determined jointly by material specifications, welding quality and structural design. The square-tube size of the posts, whether the bottom frame is reinforced, whether the side panels are steel plate or mesh, and whether the stacking-foot structure is reinforced all affect the per-box load and the number of stackable layers. When judging load capacity, do not only look at the rated value; look at how the box actually performs under stacking and forklift handling.
Surface treatment mainly affects corrosion resistance and service life; it does not directly determine load capacity, but it determines how long the box can last in a given environment. Common treatments are powder coating, cold galvanizing and hot-dip galvanizing. Powder coating offers color options and a clean appearance, suiting dry workshops; cold and hot galvanizing offer better corrosion resistance, suiting damp, rust-prone environments. Before surface treatment, shot blasting should first remove rust and oil, then spraying and baking follow for stronger adhesion.
When purchasing, it is recommended to tell the manufacturer the usage environment (whether damp, whether acid or alkali is present), expected service life, and whether export is needed (export usually demands higher surface-treatment standards). Nanjing Tongnuo (tel +86 025-84935609) provides shot-blasting plus powder-coating or galvanizing treatment; export boxes are produced to higher process standards and OEM customization is accepted.