A mould that runs 2 seconds slower per cycle is almost nothing. Multiplied by 50,000 cycles, it adds up to several hours of lost production without a single alarm going off. Injection mould fouling is one of the most underestimated hidden costs in plastics processing.
Invisible fouling, until it gets expensive
On an injection press, fouling builds up slowly: release agent deposits, carbonised resin residue, micro-deposits in the vents and cooling channels. Nothing dramatic at first. Then cycle times creep up, the scrap rate rises, and operators start improvising manual cleaning between runs, often with products or tools that end up damaging the mould surface.
The real problem isn’t visible on a single part. You see it over a month of production: longer cycles, unplanned stops for cleaning, rework on defective parts, and a mould whose service life gets shorter with every aggressive intervention.
Where does mould fouling really come from?
Three sources come up almost every time with the moulders we work with:
- Release agent residue that carbonises in the heat and builds up in the contact areas
- Gradual clogging of the vents, which traps gases and leaves burn marks on the parts
- Surface corrosion caused by residual moisture between production runs, especially on untreated steel
Traditional methods, and why they cost more than they seem
Fully dismantling the mould for workshop cleaning ties up the press for several hours, sometimes a whole day for complex multi-cavity moulds. Chemical strippers dissolve residue well, but they also attack surface treatments and leave a thin film that then has to be neutralised. Ultrasonic cleaning gives good results on small dismantled parts, but isn’t suitable for a complete mould mounted on the press. As for conventional sandblasting, it’s simply out of the question on polished or textured surfaces, because the abrasion changes the surface finish irreversibly.
Dry ice cleaning: a job with no dismantling
Dry ice blasting at -78.5 °C works differently. It lifts deposits through thermal shock rather than abrasion or chemical dissolution. The mould stays on the press, no dismantling is needed, and cleaning can be done during a planned stop between runs. The ice turns instantly into gas on contact with the surface, leaving no residue or moisture, so there’s no drying or neutralising step as with solvents.
The process is also non-abrasive. It changes neither the dimensions nor the surface finish, even on a freshly polished mould. We always test on a discreet area before any full job, to check compatibility with the existing surface treatment.
What it actually changes on your line
No dismantling means no cooling down and heating back up of the mould, which is often the longest part of a conventional clean. On a typical job, you go from several hours of machine downtime to a window of 20 to 60 minutes, depending on the complexity of the mould. On a tight production schedule, that’s the difference between cleaning that gets pushed back to the next long shutdown (and so never really happens) and preventive maintenance that’s genuinely built into the schedule.
When to think about it first
Some signs don’t lie: a gradual rise in the scrap rate with no change of material or settings, recurring burn marks near the vents, a cycle time slowly drifting upwards, or simply a high-value mould (multi-cavity, mirror-polished surface) that you don’t want to expose to abrasive methods. In these cases, a free assessment confirms whether dry ice is the right answer before you commit to anything.
Icetec works on injection moulds in Belgium and Luxembourg, with a free quote within 6 working hours. Want to know more about our approach to dry ice cleaning of injection moulds, or schedule an assessment on your press? Contact us directly.