At a Glance
Follow manufacturer maintenance intervals and record all repairs in detailed maintenance logs.
Clean coolant lines quarterly and ensure no more than 5°F temperature increase between inlet-outlet.
Replace hot runner heater bands every six to 12 months and inspect thermocouples regularly.
As the year winds down, injection molds and machines deserve a thorough tune-up to ensure smooth operations in the year ahead. Neglecting maintenance can lead to costly downtime and compromised product quality. The end of the year is a critical time to restore this equipment to optimal operating condition for the new year.
Mike Stemm, business development manager for molding supplier PCS Company of Fraser, MI, emphasizes the importance of preventive and predictive maintenance over reactive approaches.
"Tooling and machines are a costly investment deserving care and respect," he said.
PCS Company, which provides solutions and products for the injection molding, mold making, and die casting industries, has more than 40 years of field experience helping molders optimize their tooling and equipment.
Stemm shared real-world insights with PlasticsToday, explaining that the automotive industry traditionally shuts down between Christmas and New Year's, providing a quiet period to focus on maintenance, tool repairs, and tool changes. This remains an ideal time to return machines and tools to optimum condition.
Preventive vs. reactive maintenance
Stemm advised following foundational guidelines to ensure end-of-year maintenance is systematic and effective:
Follow manufacturers' recommended maintenance intervals, which can be defined by calendar and/or cycle count
Record all repairs in maintenance logs, noting preventive maintenance (PM) interval changes and replacement parts required
Adopt a robust schedule of quarterly and annual maintenance periods tied to predictive cycle counts. Digital mold cycle counters can be embedded in maintenance software
While shops often plan to perform routine maintenance based on shot data, Stemm noted that execution often falls short. "That's why it often comes down to calendar timing," he said.
Key maintenance guidelines
Assessing and addressing component wear is a somewhat subjective aspect of maintenance, Stemm explained.
"When determining wear, start with a visual review and note light scoring and deep gouges," he said. "If it is seen, then you can clean, measure, and repair as needed."
Proper lubrication is another critical factor. Stemm emphasized the importance of using high-quality lubricants that meet or exceed manufacturers' recommendations and ensuring contaminants are removed prior to lubricating.
Mold maintenance checklist
To prepare molding operations for 2026, Stemm offered a detailed checklist of maintenance tasks:
Molds
Tear down and restore molds: Devote two to three days on average, or three to five days for heavily worn molds
Gating
Confirm dimensions of cold gates to prevent cavity balance degradation
Use gate inserts for easier repair and maintenance
Venting
Clean static vents and ensure dimensions are correct
Measure, inspect, and clean dynamic vents. Use ultrasonic cleaning for porous vents
Hot runner
Inspect manifold and flow channels for leaks and wiring issues. Clean with a bake-out process above 800°F
Replace heater bands every six to 12 months and inspect thermocouples
Confirm wiring and connectors are functioning properly
Measure gate needles and tips, and repair or replace valve pins and seals as needed
Mold sensors
Recalibrate every six to 12 months, with extra sensors on hand for uninterrupted operations
Cavity & core surface finish
Clean textured surfaces with dry ice blasters and confirm gloss levels
Polish deep ribs and cores occasionally to ensure proper part ejection
Coolant circuits
Clean coolant lines and measure mold surface temperatures quarterly
Ensure no more than a 5°F increase between inlet and outlet temperatures
Ejector system
Inspect pins, springs, collapsible cores, unscrewing mechanisms, slides, and lifters for wear and replace as necessary
Date codes & inserts
Update date inserts to reflect the correct year and month
Injection machine maintenance checklist
A proper maintenance regimen for injection molding machines (IMMs) can take one to two weeks. Performing checks throughout the year shortens end-of-year repair time.
Electrical system
Inspect connection points and wires
Check integrated ancillary equipment, including robotics, mold sensors, hot runners, material hoppers, and material handling systems
Hydraulics
Inspect for leaks at pipe joints, hoses, and couplers. Repair or replace as needed
Clean the oil tank, replace oil, and inspect filters, valves, and oil coolers
Barrels, screws & tips
Confirm barrels are within spec annually, or every six months for high-wear resins
Inspect and replace screw tips on the same schedule
Cooling
Flush and descale water lines, manifolds, heat exchangers, and chillers
Calibrate coolant flow meters
Controls
Review machine logs for incidents and anomalies
Test and repair emergency stops, safety gates, and interlocks
Calibrate pressure and temperature sensors
Educational opportunity
To streamline maintenance processes and increase efficiencies, the American Injection Molding (AIM) Institute offers specialized courses tailored to maintenance personnel, managers, and tooling engineers. Course options include:
Mold Maintenance, Troubleshooting & Repair: Structured approaches to maintenance and documentation
Hot Runner Troubleshooting & Repair: Focused on hot runner systems
Mold Maintenance Strategies: Insights into managing a busy mold repair shop
Hands-on courses: Covering mold component welding, polishing, repair, and texturing
These courses provide practical knowledge and shop skills to ensure molds and machines are ready for the challenges of 2026. Stemm noted that by following these guidelines and leveraging educational resources, companies can avoid costly downtime and ensure their equipment operates at peak performance in the year ahead.
