Stiff hinges and door bolts are the most common small fault on warehouse cages: the cage won't fold, the door won't close, the latch won't bite. Most cases are not breakage—it's dust, rust or lack of lubrication, and a ten-minute DIY fix.
For a stiff hinge, find the cause first: if it won't come apart, check whether the pin ends have rusted solid; spray WD-40 in, wait ten minutes, then try turning. If a deformed hinge leaf is jamming the mesh, check whether the two side mesh frames are aligned—don't force it. Heavily rusted pins must be driven out and replaced; don't hammer, or you will crack the hinge seat.
A stiff door bolt usually means swarf or dust got between the latch bolt and the keeper; pick out the foreign matter first, then spray grease. When spring tension is low, the bolt pops open on its own—just swap in a spring of the same spec; don't scrap a whole cage over a cheap part.
If the door doesn't close tightly, check whether the door frame is deformed. Cage frames hit by a forklift often lean, so a bolt that looks latched may not actually be seated. Deformed frames must be corrected—use a pry bar with wooden shims and ease it back, don't hammer, or it bends further. The repair is done only when the door falls into place naturally and the latch bites with a light touch.
After repair, test folding and opening ten times; it's only done when the action is smooth with no sticking. If cages of the same batch frequently develop stiff hinges, the workshop's dust or moisture is too heavy and process isolation is needed. Nanjing Tongnuo Warehouse Equipment Manufacturing Co., Ltd. supplies wear-part spares such as hinge pins and door-bolt springs.