Daily Maintenance Skills for Injection Molds
Injection molds are core assets of manufacturing workshops. The maintenance condition directly affects service life, product quality and production efficiency. Molds work under long-term high temperature, high pressure and repeated opening and closing conditions. They are also impacted by scour of plastic melt, metal rust caused by moisture and friction of foreign matters. Inadequate daily maintenance will easily lead to common faults such as surface scratches, rust, stalling, water leakage and excessive flash. Implementing regular maintenance with prevention as the priority effectively reduces failure downtime and mold repair costs, and ensures stable operation of production lines. This article summarizes complete daily maintenance key points from the aspects of in-production maintenance, post-shutdown care, periodic inspection and accessory management.
Real-time Maintenance During Production
Timely protection during continuous production is critical to slow down mold loss. Before startup, inspect connection of cooling water circuits and oil circuits to confirm no leakage and unobstructed water flow, then raise mold temperature for production. Keep mold temperature stable during operation. Sharp temperature fluctuation accelerates steel fatigue and causes surface peeling and mold deformation. Ensure normal operation of vent systems. Blocked vent grooves lead to carbon deposition and local overheating, which not only damage product appearance, but also corrode mold surfaces.
Keep mold opening and closing movements stable, and avoid high-speed impact and forced mold locking to prevent deformation of parting lines, guide pins and guide bushes caused by impact. Remove flash, material scraps and carbon deposits on parting lines and cavity edges in a timely manner. Use special soft tools for cleaning. Hard metal tools are prohibited to polish forming surfaces and wear-resistant coatings artificially. Increase cleaning frequency for molds processing glass fiber materials and modified plastics to reduce friction caused by hard particle adhesion. Pay close attention to the operation of ejection systems. Stop production for troubleshooting immediately if stalling and abnormal noise of ejector pins and ejector blocks are found, to prevent cavity scratches and pin breakage.
Maintenance for Temporary Shutdown and Short-term Storage
Take phased protection measures during temporary shutdown, material replacement and shift change. For short shutdown within several hours, keep molds at proper temperature and turn off water circulation to avoid water condensation and rust on mold surfaces. If the shutdown lasts more than half a day, thoroughly clean residual plastics in cavities and runners, and wipe all forming surfaces and parting lines to keep them dry and clean without residual materials and oil stains.
Close molds completely before shutdown instead of keeping them half-opened for a long time, to prevent deformation of guide pins, springs and inserts under sustained stress. In high-humidity workshops and rainy seasons, apply a thin layer of special mold anti-rust agent on exposed metal parts such as cavities, runners and guide pins. Do not use ordinary grease to avoid mold surface contamination. Before reusing molds, thoroughly wipe off anti-rust agent with clean cloth and special detergent, to prevent oil stains from mixing into plastic melt and causing product defects.
Preservation Maintenance for Long-term Shutdown
Implement standard sealing procedures for long-term deactivation such as production suspension, long holidays and equipment maintenance. Firstly, fully disassemble and clean molds, and remove carbon deposits, dirt and dust in dead corners including runners, gates, vent grooves and gaps between ejector pins. Dry all components completely after cleaning to eliminate residual moisture. Inspect cavities and cores for minor scratches and rust spots, and polish and repair slight defects in time to prevent hidden dangers from expanding.
Carry out layered anti-rust treatment on the whole set of molds. Focus on spraying anti-rust agent on forming surfaces, guide pins, guide bushes, sliders and inclined pins. Apply protective grease on springs and small inserts separately. After anti-rust treatment, close and lock molds stably, place them on dry and ventilated mold racks with support blocks to isolate ground moisture. Avoid stacking molds to prevent extrusion deformation. Attach identification cards to mark mold number, sealing time and operating status for convenient retrieval.
Special Maintenance for Moving and Sealing Components
Moving parts are high-failure areas of molds and require independent maintenance standards. Apply special lubricating grease on guide pins, guide bushes and guide plates regularly with uniform and thin coating. Excessive grease adheres to dust and forms sludge, which increases wear instead. Adjust refueling cycle according to production load, and conduct daily inspection and refueling for high-load production. Besides regular lubrication, check fitting gaps and clean material scraps in gaps of precision moving components such as sliders, inclined pins and core-pulling mechanisms to prevent stalling and position deviation.
Inspect cooling water circuits and sealing gaskets periodically. Scale and impurities accumulate inside pipelines after long-term use, leading to poor water flow and uneven mold temperature. Clean water circuits with special descaling agents at regular intervals. Replace sealing gaskets and threaded plugs immediately once water or oil leakage is found, as minor seepage will gradually corrode mold substrates. Monitor the elasticity of springs, and replace deformed and broken springs in a timely manner to avoid abnormal mold opening and closing movements.
Periodic Inspection and Wear Prediction
Daily maintenance is not limited to surface cleaning, and shall be combined with comprehensive periodic inspection. Set inspection cycles according to production output. Stop production for full inspection after molds produce specified batches of products. Focus on detecting cavity size, surface finish and fitting status of parting lines, and check for wear, collapse and deformation. Inspect the integrity of nitride layers, hard chrome plating and PVD coatings on mold surfaces, and repair local coating peeling in a timely manner.
Fasten all screws, pressure plates and insert fixing parts regularly. Long-term vibration loosens fasteners and further causes misalignment and flash. Establish mold maintenance ledgers to record each inspection, maintenance and repair work, track mold wear conditions, predict service life of vulnerable parts in advance, and realize pre-purchase of accessories and pre-treatment of hidden dangers.
Conclusion
The core of daily maintenance for injection molds lies in frequent inspection, gentle operation, emphasis on protection and phased management. Every link including real-time protection during continuous production, phased treatment for temporary and long-term shutdown, special maintenance for moving and sealing parts and periodic inspection is indispensable. Standardized maintenance habits protect mold forming surfaces and precision structures effectively, reduce common faults such as rust, wear and stalling, extend overall mold service life, cut down repair costs and downtime losses, and lay a solid foundation for stable production and quality control.
