Introduction to Injection Mold Maintenance
Injection molds are primary equipment in injection molding production. Establishing proper mold inspection and maintenance methods is essential for effectively maintaining mold precision, stabilizing production operations, ensuring molded product quality, and reducing production process failures. Well-maintained molds perform at their best, extend service life, and ensure production continuity. As the industry saying goes: Seventy percent mold, thirty percent process. Mold maintenance is just as important as the injection molding machine itself for product quality.
Injection Mold Structure Overview
Understanding mold structure is fundamental to proper maintenance. Key components include: moving template, fixed template, cooling water channels, fixed mold base plate, locating ring, sprue bushing, core plate, guide pillars, guide bushings, moving mold base plate, support plate, limit pins, ejector plate, ejector retainer plate, sprue puller, ejector guide pillars, ejector guide bushings, ejector pins, return pins, and spacer blocks.
The mold system can be divided into eight functional sections: forming components (core and cavity that give shape to the plastic), runner system (channels for molten plastic flow), guide components (ensuring precise alignment during mold closing), ejection mechanism (for part removal), side core-pulling mechanism (for undercuts), temperature regulation system (cooling/heating channels), venting system (for air escape during filling), and structural components (plates, supports, and fasteners).
Daily Mold Point Inspection Before Production
- Open the mold slowly in stages, checking for abnormalities in the core, slide positioning balls, guide pillars, side locks, slides, and angled pins
- Check for water leaks and plastic debris on the parting surface
- If oil stains are found on the core or cavity, spray mold cleaner onto cotton and wipe the stained area, then blow dry with an air gun
- Important: Mirror-finish or electroplated molds must not be wiped with cloth; use only clean cotton for gentle wiping. Textured mold cores must never be scraped with hard objects
- Clean guide pillars, ejector pins, and return pins thoroughly and apply grease evenly (use high-temperature resistant grease for hot-runner molds)
- Open and close the mold multiple times to verify normal operation; if no abnormalities, close the mold without high-pressure clamping and clean surrounding water stains, oil, and tools
In-Production Mold Care
During normal production, keep the parting surface clean. Personnel should wipe the mold surface every 5 to 8 hours to prevent plastic threads and foreign matter from damaging the mold surface and to ensure proper product venting. For molds running on machines, operators must lubricate their molds every 12 hours to ensure normal production and prevent seizing of moving parts.
For short-term shutdowns (5 minutes to 1 hour): close cooling water, reduce material temperature, and shut down the motor. For short holiday shutdowns: close water valves, blow dry all residual water inside and outside the mold, then run a few more shots to heat the mold. Spray sufficient wax-based anti-rust agent. Keep the mold in closed position without high-pressure clamping, maintaining 1 to 3 centimeters gap between front and rear mold halves, then shut down the motor.
For long-term shutdown or mold removal: evenly spray anti-rust agent on the mold surface, paying special attention to rib areas to prevent rust. Distinguish between short-term anti-rust oil (for several days, less than one week) and long-term anti-rust oil (for over one week).
Shift Handover Procedures
- Inspect first-shot samples for flash, burrs, or other abnormalities
- Check mold upper and lower surfaces for damage or rust; verify no water or oil leaks; confirm mold opening, closing, and ejection actions have no unusual sounds
- After taking over, immediately check lubrication status of all moving mold parts; apply lubricating oil to under-lubricated areas
Post-Continuous Production Maintenance
After continuous production exceeding one month, molds require disassembly for comprehensive maintenance due to moving part wear, lubricant degradation, water leak corrosion, material decomposition corrosion, and plastic residue compression damage. Maintenance includes: rust removal from exterior, parting line, cavity, core, ejection, and slide surfaces; re-lubrication of ejection mechanisms and slides; replacement of worn components including springs, bolts, and core pins; repair of defects including flash, ejector marks, and drag marks.
