Cleaning and Maintenance Procedure for Carbon Deposits on Thermosetting Compression Moulds
During thermosetting compression molding, resin crosslinks under constant high temperature and releases small volatile molecules. After repeated production cycles, carbon deposits accumulate on cavity surfaces, vents, parting lines and flash grooves. Such deposits feature strong adhesion, triggering surface pits, color difference, mould sticking, blocked vents and abnormal flash. Severe carbon buildup may scratch polished cavity surfaces. Harsh chemical agents and rough grinding cannot be adopted for thermosetting moulds. Standardized cleaning and maintenance procedures effectively remove carbon residues while protecting mould surface roughness and fitting accuracy to support stable mass production.
Ⅰ. Pre-Shutdown Preparation and Safety Pre-Treatment of Moulds
Follow standardized shutdown procedures before carbon cleaning to prevent scalding and mould collision risks. Gradually reduce mould temperature as required by process, and open the mould only after temperature drops below 80°C. Disassembly under high temperature is prohibited, as cleaning agents volatilize rapidly and leave residues, alongside high risk of burns. Switch off hydraulic and heating systems and hang warning signs to avoid accidental startup. Remove excess raw material residue on mould surfaces with copper shovels. Never use steel tools to contact molding surfaces to prevent scratches. Observe carbon distribution, and distinguish heavily carbon-blocked vents, lightly contaminated cavity appearance surfaces and guide mechanisms. Establish differentiated cleaning standards to avoid surface damage from uniform full-area treatment. Record blocked vents as priority cleaning targets.
Ⅱ. Focused Carbon Removal on Parting Lines and Vent Grooves
Parting surfaces and vents are major accumulation zones for volatile precipitates, forming hard carbon deposits that require priority treatment. Deploy dedicated thermoset mould carbon cleaner, non-woven cloth and copper brushes. Cover carbon areas with cleaner-soaked fabric for sufficient penetration to soften carbonized layers. Gently scrub along mould texture with soft copper brushes, and use thin copper strips to dredge narrow vent slots thoroughly. For stubborn carbon deposits, apply repeated soaking and layered stripping instead of heavy friction. Wipe residual chemical agents completely after cleaning. Remnants will generate white haze and contaminate molded parts in subsequent cycles. Take care to preserve sealing edges of parting lines; over-polishing causes sealing surface collapse and continuous flash in production.
Ⅲ. Fine Carbon Removal for Cavity Molding Surfaces
Appearance cavity surfaces demand strict roughness control and represent the key maintenance challenge. Hard abrasive tools are forbidden. Thin light carbon contamination can be wiped repeatedly with cleaner-impregnated non-dust cloth to dissolve carbon layers chemically. Moderate deposits can be treated with superfine diamond polishing compound and soft wool felt under low speed. Maintain consistent polishing direction to avoid random scratches. Polished mirror surfaces cannot use steel brushes or ordinary sandpaper. For isolated stubborn carbon spots, apply cleaning agent locally instead of large-area coating to reduce erosion of mould nitride layers. Conduct repeated wiping after cleaning to confirm zero carbon spots, no chemical residues and micro scratches, ensuring product appearance quality.
Ⅳ. Protection and Rust Prevention before Mould Assembly
After cleaning, remove carbon dust from gaps of guide pins, guide sleeves, ejectors and inserts. Apply high-temperature resistant lubricant to sliding components to prevent jamming and abrasion caused by impurities. Confirm cavities and parting surfaces are fully dry with no chemical residue. Select protection solutions according to production schedules: wipe thoroughly for short-term continuous production and preheat after mould closing. For long-term storage, evenly spray high-temperature mould anti-rust agent to isolate air and oxidation. Double-check vents before mould closing and ensure no cleaning debris remains inside to avoid cavity crushing damage.
Ⅴ. Establish Periodic Preventive Maintenance Standards to Slow Carbon Formation
Passive cleaning cannot fundamentally resolve carbon accumulation. Normalized preventive measures extend maintenance intervals. Strictly control compression molding temperature to avoid excessive heating that accelerates resin decomposition and volatile emission. Implement simple vent cleaning every shift to stop thin carbon layers from hardening gradually. Optimize raw material preheating and compression holding parameters to reduce volatile output. Formulate regular cleaning plans based on material type and production rhythm, including daily simple maintenance, weekly deep cleaning and monthly full disassembly inspection. Build maintenance logs recording carbon status, cleaning methods and mould surface conditions to predict deterioration and prevent sudden quality failures.
Conclusion
Carbon cleaning and maintenance of thermosetting compression moulds follow a complete workflow: safety pre-treatment, zoned cleaning, fine treatment of molding surfaces, post-job protection and proactive prevention. Prioritize dredging vents and parting lines, and adopt mild refined cleaning for appearance cavities to avoid precision damage from hard tools. Rust protection, lubrication and residue control after cleaning prevent secondary problems. Relying solely on shutdown cleaning delivers temporary improvements. Combined periodic maintenance and stable molding temperature and ventilation conditions slow carbon buildup. This standardized procedure balances cleaning performance and mould protection, reduces appearance defects, sticking and blocked vents caused by carbon deposits, lowers polishing and mould repair frequency, extends mould service life and improves production yield.
