Injection mold maintenance management
Injection mold maintenance management is critical to ensuring production continuity and reducing costs. A comprehensive preventive maintenance system, including daily inspections, regular maintenance, and fault warning mechanisms, is essential. Daily inspections should focus on the wear of vulnerable parts (such as ejector pins, guide pins, and seals). A production line, during a five-minute pre-shift inspection, discovered loose ejector pins in 30% of its molds. Prompt tightening prevented scratches on batches of molded parts. Regular maintenance should be planned based on mold runs or schedules. Typically, a comprehensive maintenance is performed every 10,000 mold runs, including cavity cleaning, grease replacement, and clearance testing. After regular maintenance, the sudden failure rate of a certain automotive mold dropped from 8% to 2%. Fault warnings can be achieved through the installation of sensors. In one smart factory, molds are equipped with temperature and vibration sensors. When abnormal data (such as a sudden temperature rise of 5°C) is detected, the machine automatically shuts down and issues an alarm, reducing fault resolution time from 2 hours to 30 minutes. The core of maintenance management is recording and analysis. Maintenance files are established for each mold, including the type of failure, replacement parts, and maintenance costs. A company analyzed 500 maintenance records and found that 70% of the failures were caused by insufficient lubrication. After targeted improvements, maintenance costs were reduced by 30%.
Classifying and addressing common mold failures is fundamental to maintenance management. Standardized maintenance procedures should be developed based on the nature of the failure to improve maintenance efficiency. Cavity surface damage (such as scratches and dents) requires polishing or repair welding. For example, a mirror-finished mold had a cavity scratch 0.05mm deep. By polishing with graded sandpaper (800#-1500#) and diamond paste, the surface roughness was restored to Ra 0.02μm, costing only 200 yuan. A 1mm deep dent, on the other hand, required repair welding with argon arc welding, costing 2,000 yuan and requiring remachining of the cavity dimensions. Ejector mechanism failures (such as bent ejector pins and stuck ejector plates) are often caused by poor lubrication or foreign matter. In one mold, the bent ejector pin was caused by iron filings entering the guide hole. After cleaning, the ejector pin was replaced (costing 50 yuan) and a magnet filter was added. The same type of failure has not recurred within three months. Cooling system failures (such as clogged water channels or leaks) require high-pressure water jet flushing or replacement of sealing rings. For example, scale clogged the water channels of one mold, resulting in a 40% drop in cooling efficiency. Chemical cleaning restored the system to normal operation, and the repair cost was 800 yuan, far less than the 5,000 yuan required to replace the water channel inserts. For complex failures (such as cavity cracking), the cost of repair must be assessed. For example, the cost of repairing a five-year-old mold that cracked reached 30% of its original cost. Ultimately, the mold was scrapped and replaced with a new one to avoid repeated repairs that would impact production.
The management of spare parts directly impacts maintenance efficiency, necessitating a rational inventory and procurement mechanism to ensure the availability of critical spare parts. A certain inventory of consumable parts (such as ejectors, springs, and seals) must be maintained. One factory maintains a stock of ejectors covering common specifications (diameters 3-12mm, lengths 50-200mm), reducing the waiting time for ejector replacements from two days to one hour. Standard parts (such as guide pins, guide bushings, and sprue bushings) can be processed under a VMI (vendor managed inventory) agreement with suppliers. One company used this approach to increase inventory turnover by 50% and reduce capital tied up by 30%. For non-standard parts (such as cavity inserts and special cores), drawings must be retained and two or three high-quality suppliers must be selected to ensure delivery within 48 hours in the event of an emergency repair. For example, a supplier completed machining of a damaged special-shaped insert in a mold within 40 hours using drawings, saving three days compared to when no drawings were available. Spare parts storage needs to be moisture-proof and rust-proof. A factory’s spare parts warehouse uses a constant temperature and humidity environment (25°C, 50% humidity), combined with anti-rust oil and vacuum packaging, to extend the shelf life of spare parts from 6 months to 2 years.
Controlling repair costs is a key management priority. This requires reducing expenses through process optimization and increasing reuse rates, while also ensuring repair quality. A modular repair concept was adopted, breaking down the mold into multiple modules (such as the cavity module and ejector module). For a complex mold with an ejector module failure, disassembling and repairing it individually saved 60% of labor hours and reduced repair costs by 40% compared to disassembling the entire mold. Reusable repaired parts are rigorously inspected. For example, a repaired cavity insert had a dimensional deviation of 0.01mm, meeting service requirements, and its reuse cost was only 20% of a new part. Repaired parts with excessive precision are resolutely eliminated. For example, a gear cavity had a pitch deviation of 0.03mm after repair, failing to meet requirements, but continued use resulted in a 5% increase in the scrap rate and increased costs. The balance between outsourcing and in-house repairs should be determined based on the difficulty of the problem. Simple repairs (such as ejector pin replacement) can be completed in-house (lower cost), while complex repairs (such as mirror polishing) can be outsourced to specialized vendors (higher quality). One company achieved a 25% reduction in overall repair costs through this strategy. Regular evaluation of the maintenance input-output ratio revealed that the average annual maintenance cost of a certain mold accounted for 15% of the original cost, which was higher than the industry standard of 10%. Analysis revealed that this was due to mold aging. The decision was made to replace the mold in advance, which actually reduced long-term costs.
The development of a maintenance team is a core resource for maintenance management, and training and incentive mechanisms are needed to enhance technical capabilities and motivation. Skills training should cover both theoretical and practical aspects. One company conducts training twice a month, covering topics such as mold structure, material properties, and the use of maintenance tools. This, combined with practical assessments, has resulted in a 50% improvement in maintenance personnel’s ability to handle complex faults. Equipped with specialized maintenance tools (such as coordinate measuring machines, ultrasonic cleaners, and precision grinders), a factory’s maintenance workshop invested 100,000 yuan in these equipment, improving maintenance accuracy from ±0.05mm to ±0.01mm and increasing the repair pass rate from 85% to 98%. By establishing an incentive mechanism that links maintenance efficiency and quality to performance, the maintenance team on one production line received additional rewards for completing emergency repairs ahead of schedule, significantly boosting employee motivation and reducing average repair time from 4 hours to 2.5 hours. Cross-departmental collaboration is also crucial. The maintenance team regularly communicates with production and design departments. In one case, a cooling water channel improvement suggestion provided by the maintenance team was adopted by the design department, reducing the failure rate of similar molds by 60%.
