Rust Prevention Solutions for Long-term Storage Protection of Injection Molds

Rust forms easily on mold cavity, core, slide and lifter surfaces when molds are stored or idle. Moisture, plastic decomposition residue and corrosive workshop gas will leave pitting corrosion, scratch marks and dimensional deviation. A complete rust protection system includes pre-storage cleaning, rust inhibitor selection, sealing packaging, environment management and regular re-inspection.

Cleaning and dismantling before storage

Clear plastic residue, acidic volatile substance in cavities, runners and vents. Glass-filled and flame-retardant plastics have stronger corrosion. Soft copper brushes and dedicated mold cleaner are used without sandpaper or hard scrapers. Drain all cooling water and blow dry channels with compressed air. Wipe oil and dust on guide pins and slide rails. Light rust spots are polished gently with mold rust remover before preservation.

Select rust preventive agents by storage cycle

Thin-film displacement anti-rust oil fits short-term shutdown within 7 days, easy to wipe before restarting. Anti-rust grease with dense oil film is suitable for medium and long-term storage from two weeks to half a year, applied thickly on threads and tiny inserts. VCI anti-rust paper and bags are used for long-term storage or ocean shipment. Volatile inhibitor molecules reach narrow gaps which spray oil cannot cover.

Mold sealing and packaging operation

Only pack after full cleaning and drying. Wrap cavity and core with VCI paper and seal with PE bags. Do not fully seal airtight, as condensation may form under temperature fluctuation. Lock ejector plates, slides and lifters to avoid collision and scratch of protective oil film. Hot runner molds install protective caps on nozzle tips to protect heating coils and thermocouples.

Storage environment management

Place molds on raised shelves in a dry warehouse, with humidity controlled below 60%RH. Keep away from windows, water pipes and spilled cooling water. Polished mirror, nitrided and PVD coated molds are stored separately. Temporary storage area in workshop should stay away from cooling spray zones and flame-retardant molding stations with acidic volatile gas.

Periodic inspection and re-maintenance workflow

Carry out inspection every 30 days normally, and shorten the cycle to 15 days in rainy seasons. Re-clean and reapply rust preventive if oil film is damaged. Before production, remove all anti-rust medium completely with degreaser to avoid bubbles and silver streaks on plastic products. Nitrided and coated molds have better anti-rust performance, but corrosion will still happen once the coating chipped. Multi-cavity small molds for coil seals and threaded plugs need more careful cleaning for narrow gaps. Rust protection works only based on thorough cleaning.