Cleaning, rust prevention, cooling channels and records - how to make a mould worth thousands last for millions of shots.
Every machine in the plant can be replaced from a catalogue within weeks. Your moulds cannot: each set is a custom precision part carrying your container's design, your neck standard and your production quality. A $10,000 mould maintained on a schedule runs for millions of shots; the same mould neglected dies in a season - rusted, scored and leaking quality with it.
This guide is the maintenance schedule most plants never write down. It pairs directly with the blow and injection defect guides - because many "machine problems" are actually mould problems: blocked vents, scored parting lines and scaled cooling channels.
The ScheduleVisual check of first-off parts, wipe the parting line if visible flash or residue appears, confirm mould water flow and temperature.
Clean and blow out vents, inspect the parting line under light, check ejector pins and guide pillars, log shot counts.
Full cavity wipe-down with approved solvent, deeper vent cleaning, verify clamp surfaces, check cooling flow rates against baseline.
Full strip-down deep clean, chemical flush of cooling channels, re-polish cavities where needed, replace worn seals and O-rings.
The fastest way to ruin a good mould is cleaning it badly. Brass and copper tools only near cavities - steel scrapes, and one scratch across a parting line becomes permanent flash on every shot.
Brass scrapers, copper brushes, plastic picks for vents. Never steel, never sandpaper on cavity surfaces - use polishing compounds and felt only.
Use mould-specific cleaners or the solvent your material supplier recommends. Harsh solvents attack the steel's protective surface and residue can contaminate the next batch.
Clogged vents cause burn marks and short shots - clean them weekly with vent-cleaning tools, never drill them wider out of frustration. Vent dimensions are engineered.
Never open a hot mould full of molten material. Purge, cool, then clean. Impatience here causes the burns and dents we see in for refurbishment.
Moulds rust fastest when not running. Never store a mould wet: dry it completely, spray cavities with rust-preventive oil, close the halves, and store in a dry, stable-temperature area. Coastal and humid climates need dehumidified storage - humidity finds every polished steel surface.
Hard water leaves scale inside cooling channels that acts as insulation - cycle times creep up weeks before anyone notices. Flush channels with chemical descaler every 3-6 months, use treated water in the circuit, and log flow rates monthly: a falling flow rate is scale announcing itself.
Starting a cold mould in humid air sweats water onto the cavity. Warm moulds to just above dew point before opening the water circuit - a ten-minute habit that prevents a season of rust spots.
One record per mould: shot count, cleaning dates, vent work, repairs, and the defect history from the troubleshooting log. The card tells you when refurbishment is due - before quality tells the market.
Refurbish when damage is local: parting lines re-machined, vents re-cut, surfaces re-polished - typically 10-20 percent of replacement cost. Replace when cavities are corroded or cracked, or the product design has moved on. Our engineers assess from photos, free, via the contact desk.
Aluminium blow moulds: millions of shots with care. Steel injection moulds: 1-10 million cycles by grade. The difference between the top and bottom of those ranges is exactly the schedule on this page.
Wipe the cavity and parting line at every mould change, clean vents weekly in production, and do a full deep clean - including cooling channels - every 3 to 6 months depending on material and water quality.
Never store a mould wet: dry it, spray cavities with rust-preventive oil, and store in a dry, temperature-stable area with mould halves closed. Coastal plants need extra vigilance - humidity is the mould killer.
Scale and biofilm build up inside channels, cutting cooling efficiency and cycle time. Flush with a chemical descaler every 3-6 months, use treated or filtered water in the circuit, and log flow rates to catch blockage early.
A well-maintained aluminium blow mould serves millions of shots and a steel injection mould 1-10 million cycles depending on grade and care. Neglect shortens this dramatically - rust and scored parting lines end moulds early.
Refurbish when damage is local: scored parting lines can be re-machined, vents re-cut, and surfaces re-polished for a fraction of replacement cost. Replace when the cavity itself is corroded, cracked, or the product design has changed.
Send photos of the mould and your shot counts - our engineers assess it free within 24 hours. Replacement moulds built to your existing designs ship worldwide.