Molding Site Maintenance Basics: Preventive, Predictive and Breakdown Maintenance
Neglecting equipment maintenance at molding sites can cause various problems with molded products, injection molding machines, molds, and peripheral equipment, potentially impacting production schedules. This guide covers essential maintenance types and management strategies.
Three Types of Maintenance
Maintenance can be broadly categorized into three types:
1. Breakdown Maintenance
- Performed after equipment has already experienced functional degradation or stopped working. Involves identifying causes, replacing parts, and performing repairs.
- Effective when repairs are simple and can be completed quickly with minimal production impact.
- For minor faults, quick resolution is often possible through spare parts replacement.
- However, severe failures requiring extended repair time or parts procurement cannot be adequately addressed through breakdown maintenance alone.
- Mold failures in particular require significant time to repair and greatly impact production.
2. Preventive Maintenance
- Planned, periodic inspection, parts replacement, and repair performed according to predetermined standards.
Time-Based Maintenance (TBM):
- Predetermined inspection and replacement time intervals.
- Based on accumulated operational hours or molding cycles.
Condition-Based Maintenance (CBM):
- Predetermined component condition criteria for replacement.
- Requires establishing component lifespan and degradation judgment standards.
- Critical to accumulate past failure data and maintenance details for developing appropriate maintenance plans.
3. Predictive Maintenance
- Senses equipment condition and analyzes collected data to predict failure location and timing.
- Enables parts replacement or repair at optimal timing before failure occurs.
- While mold predictive maintenance is still in the practical application stage, some equipment can perform predictive maintenance through log data analysis.
- Various molding machine manufacturers have begun partial practical implementation in recent years.
Common Problems from Poor Maintenance
Mold issues: water leakage, abnormal sounds, flash/burr formation, pin deformation and breakage, cavity scratches, PL surface damage, mold rust, abnormal temperature rise, abnormal mold movement, mold opening/closing abnormalities.
Product issues: flash generation, products not releasing, foreign material appearance defects, cavity-to-cavity variation, shape defects, dimensional defects.
Machine issues: heater disconnection, abnormal mechanical movement, abnormal temperature rise, abnormal holding pressure, abnormal sounds, abnormal circulation, conveyor system stoppage.
Four Key Maintenance Principles
- Principle 1: Regularly inspect mold and machine movement, vibration, and sound to detect abnormal signs. Changes in these parameters may indicate developing issues, though this relies on experienced technician judgment.
- Principle 2: Regularly inspect product dimensions and appearance to detect defect trends. Dimensional trend management can detect early signs of mold wear or release problems. For appearance defects, carbon buildup is often the main issue — monitoring for yellow or brown oxides as precursors to carbonization allows intervention before carbonization occurs.
- Principle 3: Establish and execute maintenance plans. Accumulate past failure and repair knowledge to determine appropriate cycles, inspection points specific to each mold, and maintenance content.
- Principle 4: Prepare spare parts for fault situations. For molds, prepare easily breakable insert pins. For equipment, balance risk and cost for components with long delivery times.
Maintenance Data Management
- Centrally manage mold specifications, design drawings, molding records, injection conditions, problem records, and mold location data together.
- Retain information with universal applicability to enable organizational experience accumulation rather than just listing isolated facts.
Implementing systematic maintenance strategies at molding sites ensures stable production quality and extends equipment service life.
