Do you have cooling problems with
your injection moulding tools?
Does this mean that you cannot reach your desired cycle time? Or, do you have quality
Is your water cooling not able to eliminate the hotspots?

Stemke Cooling
Refrigerant cooling

We optimize your cooling circuit for injection moulding processes

Our refrigerant cooling ensures that injection moulding tools are kept at a constant temperature. This is essential because when the injection moulding tool is kept at the optimum temperature you achieve consistently high injection moulding quality and profit from a measurable increase in productivity.

Our focus is on shortening cycle times with at least constant or even improved part quality. Our temperature control system is specifically matched to the injection moulding tool and reduces the injection process cycle time by an average of 30 percent. Our refrigerant cooling system enables mould cores, webs and the smallest areas of less than 8 mm diameter to be precisely and accurately brought to the desired tool / demoulding temperature. A homogeneous injection moulding temperature profile delivers abundant benefits with regard to productivity and parts quality.

What problems are you having with your part? Are there unwanted glossy spots? Is the quality not as good as it should be? Or do you experience hotspots during the production of the parts that determine the cycle time, lower productivity and cause considerable added cost?

We will work with you to find the right solution. So don’t hesitate any longer; join us and switch your quality and cycle time to the fast lane!

Unique, very quick and precise.
Straight to the point.

Injection moulding tool temperature control – when can Stemke cooling help?

The problem: The water cooling ducts usually require a minimum cross-section of 6 to 10 mm. This means that water cooling of thin-walled sections and smaller areas such as mould cores, domes or webs is often very ineffective or not possible at all. The resulting hot spots have an unfavourable effect on the cycle time.

The consequences: The injection moulding tool cannot be continuously cooled.  The cooling process requires more time and the cycle time is prolonged.

The solution: Stemke’s refrigerant cooling system can also efficiently cool highly filigree mould cores or webs with contours of up to 2 mm in diameter or of 2 mm wall thickness. The thermal energy introduced is transferred to the expanded refrigerant in the core and transported out of the injection moulding tool. Areas that determine the cycle time are very quickly brought to the demoulding temperature.

Advantage: All of the hotspots are eliminated. An average cycle time reduction of 30 percent is achieved with at least constant or even improved part quality. One further plus is the environmental friendliness of the refrigerant cooling; the cooling unit has an integrated compressor that enables the refrigerant to be reprocessed.

The medium circulates in a closed system – so no liquids or gases are released.

Refrigerant cooling – how the refrigeration circuit works

The refrigerant is fed into the injection moulding tool in a liquid state from the cooling unit (temperature control unit) via a pipe or hose connection.

At the position to be cooled the refrigerant expands in an evaporation space created for this purpose, and can be thought of as releasing “cold”. The gaseous refrigerant extracts and absorbs thermal energy from the surrounding area. The process is referred to as the saturation of the refrigerant. The saturated refrigerant gas is then fed back into the cooling unit, where it is compressed to high pressure and again absorbs thermal energy. The hot refrigerant gas subsequently passes through a heat exchanger, which brings this gas back into the liquid state. In this way, the refrigeration cycle runs in a closed system without any losses.

Our cooling unit has a specially developed control that also precisely regulates the quantity and temperature of the refrigerant. Temperature sensors are integrated into the areas of the injection moulding tool to be cooled. These are placed as close as possible to the position where expansion takes place enabling precise temperature measurements to be transmitted to the control unit at all times. Temperatures increase rapidly when the liquid plastic is injected into the mould. If the set limit temperature of the injection moulding tool is exceeded the control unit begins sending a pulsed control signal to the solenoid valves. This causes refrigerant to be pulse injected into the areas to be cooled, the refrigerant expands and as it changes state form a liquid to a gas, it absorbs thermal energy from the hotspots. The pulsed injection of the refrigerant continues until the desired demoulding temperature has been reached and the component can be ejected.

The Stemke cooling system offers a reliable solution for the cooling of injection moulding tools at very favourable cost. The system always keeps injection moulding tool temperatures within the optimum range, even in critical hotspots.

Besides being easy to retrofit into existing injection moulding tools, the Stemke cooling system is also ideal for use new injection moulding tools.

Examples of injection moulding tool cooling:

Cooling unit design

Our solution for cooling injection moulding tools is available in the following performance classes:

Cooling devicesCS 400CS 600CS 800
Cooling capacity Q at t0=-10°C1,9 kW4,3 kW8,9 kW
Cryogen filling quantity3 kg ≙ 11,76 t CO2-Äq.5 kg ≙ 19,6 t CO2-Äq.10 kg ≙ 39,2 t CO2-Äq.
Dimensions B x H x T410 x 770 x 773 mm410 x 770 x 773 mm605 x 830 x 1130 mm
OperationSPS over B&R touch displaySPS over B&R touch displaySPS over B&R touch display
Number of control loops4 - 364 - 364 - 36

FAQs regarding the topic of refrigerant cooling

The cause of this problem is almost always areas referred to as hotspots, which extend the cooling time. Hotspots are areas in injection moulding tools where because of the geometry an effective cooling with common media such as water or oil is not possible. These areas are therefore decisive for the overall residual cooling time of the part. Stemke cooling eliminates these hotspots by the controlled injection of refrigerant. This reduces the cooling times so drastically that quality of the part is improved.

One cause of these quality problems may be the inconsistent cooling behaviour of the injection moulding process. Once again, Stemke cooling is ideal for eliminating this problem because the system ensures controlled temperature balance and homogeneity of the cooling behaviour. These quality problems are consigned to the past.

Hotspots are particularly likely to occur at very thin or particularly small, cores with a complicated shape that cannot be cooled with conventional methods. The result is extended cooling time and quality problems. The targeted use of Stemke cooling makes it possible to cool even the smallest point of less than 8 mm diameter very quickly and precisely. The measurable system cycle times are reduced and the injection process improved.


We love to explain you the Stemke Cooling System personally. Contact us or let us call you back!