RUBBER & PLASTICS
CLEANER WATER – BETTER PRODUCTION
Dave Roberts, Service Manager at ICS Cool Energy UK, believes water treatment is the most overlooked service in plastics moulding cooling and temperature control – and explains the cost implications when it’s ignored
H
ere is how water treatment issues in the plastics moulding cooling typically unfold. A temperature control unit (TCU) starts causing problems. Parts come off the mould inconsistently. Cycle times creep up. The issues persist for weeks, sometimes months. Eventually, a service engineer is called in. By that point, the damage is almost always beyond economical repair. Recommendations are made: filter installation, draining the system and refilling with treated water, but by then all the damage has already happened. A new TCU may be ordered. It arrives, gets installed, and is immediately introduced into the same environment, the same untreated water system that caused the original problems. The cycle begins again. “Rather than fixing the root cause, customers buy a new pump, a new heater element, then a new TCU. And then face the same problems all over again,” said Dave Roberts. This pattern is well recognised by service engineers. When a TCU fails, the customer blames the unit. The engineer knows the water is at fault. That is a hard conversation to have at the best of times, but it is especially difficult when you are effectively telling the customer the problem is their own, in the middle of a production crisis.
What makes this particularly damaging is that many TCUs are not especially expensive to replace. So rather than investigating the root cause, some operations simply buy another unit when one fails, put it on the same system, and wait for it to degrade in turn. It is not treating the problem at the source. It is costing potentially thousands more in new equipment, repeatedly, without ever resolving the underlying issue. The cost of this pattern is difficult to quantify
precisely. It depends on the number of machines, the number of moulds, the cycle time, and the value of what is being produced. It could be a small component or a large, high-value part. But in every case, poor water quality means a higher cost per hour, per day, and per year of lost or degraded production. Service engineers are typically only on site once or twice a year for scheduled servicing. For the rest of the year, the water system is entirely in the customer’s hands. Proactive advice can be given at the commissioning of the system or at the start of a service contract – what to monitor, what treatment routine to follow – but very few customers act on it until they see a problem. And by then, the advice arrives too late.
What water actually does to your systems In plastics manufacturing, three things are non- negotiable: tight temperature control, fast heat transfer, and consistent uptime. TCUs exist to deliver
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all three circulating heated or chilled water through micro-channels within the mould tool to maintain precise process temperatures. Water quality is the critical variable that determines whether they succeed or fail.
Poor water quality leads directly to longer cycle times, inconsistent parts, higher scrap rates, and unplanned downtime on moulding machines. The micro-channels within mould tools are extremely fine and block very easily. Any sediment, scale, or corrosion debris in the water circuit will restrict flow, disrupt temperature control, and compromise part quality.
Why TCUs are particularly vulnerable TCUs operate at higher temperatures than standard cooling circuits, and this is what makes water quality especially critical within them. Elevated temperatures accelerate corrosion. They also destroy inhibitors in the system faster. Even a water treatment programme that would survive in a standard cooling circuit will fail more quickly inside a TCU running at high temperature. Poor water that might last elsewhere will fail sooner in a TCU. The consequences are wide-ranging. Sediment accumulates in the bottom of the tank and blocks internal components. Heater elements burn out. Pump failure, sticking valves, blocked heat exchangers, all of these can be caused by poor water quality inside a TCU.
In more severe cases, the risks go beyond equipment damage. One documented incident
PROCESS & CONTROL ENGINEERING | MAY 2026
involved a pressurised system running at 140°C: heat transfer components became blocked, causing superheated water to spray onto the factory floor next to an operative. The customer blamed the unit. The unit was not at fault. Water quality was the cause.
The mould change and the contamination There is a structural challenge specific to the plastics industry that can continuously reintroduce contamination into water systems: mould changes. When a mould is taken off the press, it is disconnected from the water circuit and put on a shelf. Residual moisture inside the mould’s micro- channels oxidises during that storage time. Sometimes it’s months, sometimes it’s a year or even longer. Rust forms. When the mould is reinstalled and reconnected, that rust and debris goes straight into the water system. The nature of how mould storage works is that
the front face of a mould tool is always kept clean and polished. The internal workings are routinely corroded. Unless a plastics company runs every mould indefinitely without ever taking it off the press, which is not commercially realistic, some degree of contamination on reconnection is unavoidable. Cleaning every mould thoroughly every time it comes off the press is equally unrealistic in practice. This means ongoing filtration and water management are not optional extras. A well-treated system will be regularly challenged by reintroduced debris from mould changes. Without filtration in
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