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Extrusion - zonal temperature control: Efficient temperature control with Tool-Temp units
Precise temperature control is essential throughout the entire extrusion process. We will help you determine which temperature control unit is right for your production processes.
Temperature control and cooling units from Tool-Temp optimise and control the temperature for process steps such as melting, compounding, homogenising, conditioning and removal. Temperatures may need to be raised or lowered on a zonal basis depending on the product and production methods.
There are a range of clear advantages to using temperature control units with liquid heat transfer mediums. Alongside homogenous heat distribution, heat delivery and removal are simultaneously controlled within a temperature zone. Precise and fast changes in temperature improve the structure of the material and helps ensure an optimum surface quality. The improved conveying characteristics allow for high throughputs whilst maintaining the same level of quality and increased energy efficiency.
In order to keep up with the ever increasing market demands on production and quality in extrusion processes, we offer a wide range of high performance, fast and precise temperature control units.
Tool-Temp temperature control units in the extrusion process:
Robust, durable and designed for 24/7 operation: Temperature control units for use in your extrusion process.
Tool-Temp products are developed and produced exclusively in Switzerland. Starting in the development phase, careful attention is given to the selection of high-quality components for our products. All parts that come into contact with water are made of stainless steel or bronze Tool-Temp does not use any flexible joints in its products, choosing to use only robust piping. All control units make use of the latest technology to precisely regulate the temperature to within one tenth of a degree. They also feature integrated flow rate measurement which constantly monitors circulation of the medium.
Tool-Temp possesses a high degree of vertical integration, guaranteeing quality at every stage of production. Key components such as pumps, heat exchangers, flow sensors and special switches and relays are produced at the factory in Sulgen.
Short response times for bespoke customer solutions are an integral part of the service we offer. We ensure optimum temperature control so that you can concentrate on your extrusion production process.
Extrusion - zone temperature control -Efficient temperature controlwith Tool-Temp units
What is extrusion?
Extrusion is a process in which conveyor equipment (extruders) based on the principle of an Archimedes screw pushes a viscous mass under high pressure evenly through a shaped opening. This creates a solid, known as the ‘extrudate’, that has a cross-section in the shape of the opening. Theoretically, this extrudate can be of any length. Our temperature control units can deliver optimum temperature control for these complex processes.
Design and function of an extruder
An extruder fundamentally consists of a screw shaft inside a screw cylinder whose inner diameter is roughly the same as the outer diameter of the screw. At the front end of the cylinder is an opening, known as the ‘nozzle’. The screw is mounted at the rear end of the cylinder. This is where the motor is located. This motor is usually an electromotor with a gear unit. These gears are responsible for controlling the rotation of the screw. In most cases, the material being used is continuously fed into the cylinder from above via a funnel. When using multi-component materials, it is important to ensure that the composition is precisely dosed and reproduceable. Depending on the regulating mechanism used, either gravimetric or volumetric dosing is used.
If additional components are required for the extrusion, these can be added via a needle valve or side feed into the screw cylinder – this process is known as coextrusion. When working with plastics, for example, dyes (masterbatches), antioxidants, plasticizers or reinforcing fibres can be added.
Controlling the temperature of an extruder – with a process thermostat from Tool-Temp
Extrusion process – excellent temperature control for your processes with temperature control units from Tool-Temp
An extruder can be used for a range of different tasks. It can be used for mixing, compacting, blending, degassing and granulating a material. Depending on the base material and the intended end product, different designs are used. Piston, screw, double screw and planetary roller extruders are among the designs available.
Extrusion using an extruder is a versatile process for working with elastomers and thermoplastics, but also foodstuffs and pet food.
Extrusion has become an important technical process within the plastics and food industries as well as in recycling. A huge range of products can be produced using extrusion. Products that can be produced using extrusion include pipes, poles, window frame profiles, seals and tubes. Semi-finished products, sheets for use in thermoforming, films, polystyrene hard foam panels, small automotive parts and bicycle wheel rims are also among the wide range of things that can be produced, along with pasta products, snack foods, biscuits, reformed meat and pet food.
The various different properties of different materials have resulted in the development of a large number of different processing methods. Extruders can be divided into two fundamental types: processing and compounding extruders. Processing extruders usually have a single screw and are primarily used for forming operations. Compounding extruders are used when chemical and/or physical modifications to the material are needed. Double screw extruders and mixers are often used in this case.
- Cold extrusion
Low pressures, low temperatures and shearing forces - Warm extrusion
Low pressures, higher temperatures - Hot extrusion
High pressures and high temperatures - Coextrusion
Merging of two similar or dissimilar materials before they leave the profile nozzle. This is either a single-step or two-step process.
A. Plastics industry and plastics processing
Tool-Temp temperature control systems bring proven and robust technology to your extrusion production process. We will be happy to pass on our many years of experience and develop a customised solution that precisely meets the temperature control needs of your process.
Extrusion can be used to produce seamless plates, pipes and profiles with a constant cross-section. Alongside semi-finished products, extruders are regularly used as a preliminary stage for injection moulding.
When extruding plastics, heating bands are attached to the screw cylinder to melt the plastic granules or powder. Depending on the plastic being used, equipment to pump out gases may be required to prevent bubbles from forming in the end product. Extruders do not need to be heated, while there are a few processing techniques where it is necessary to cool the plasticized material. This cooling is done either using cooling blowers or cooling channels integrated into the cylinder through which a cooling medium flows. Thermoplastics and thermoplastic elastomers are usually used in extrusion. Thermosetting plastics are extruded only in special cases. Various methods can be used:
Sheet extrusion
The plasticized material is pressed through a wide slit nozzle and then smoothed out across a three-roller machine at decreasing temperatures and brought to the right thickness. Once cooled, the product is cut into sheets.
Pipe and profile extrusion
This type of extrusion presses the plasticized material through a ring or profile nozzle, it is then calibrated and cooled. Pipe and profile extrusion requires that the extruded material is cooled in a calibration table so that it does not deform. The core of the calibration table is the sizing sleeve, the primary function of which is to ensure the pipe or profile retains its shape. This is positioned directly after the nozzle on the extruder and consists of a metal block, the interior of which is precisely the same size as the pipe or profile cross-section. Calibrating hollow profiles uses inflation air or a vacuum. The extruded pipe or profile passes through the calibration sleeve. The shape of the profile is maintained inside the sleeve using air or a vacuum. Vacuum openings at various point in the sleeve along the length of the cross-section suck the profile against the inner walls while water flows through and around the profile to cool it. The exact type and shape of the calibration table depends on the plastic product to be extruded. Complex profiles such as window frames require a lot of expertise to ensure that the profile does not sag inwards on itself and become deformed while being cooled.
Film extrusion
The plasticized material is pressed through a narrow slit nozzle and drawn over cooling rollers as well as being stretched through a rolling mill. This process can produce films with thicknesses of 8-15 µm and a width of up to 4 m.
Blown film extrusion
Extruders are also found in blown film production systems. In this process, rather than extruding a profile, the plasticized material is blown into an extremely thin film bubble. The molten material is guided vertically upwards and through spiral mandrel dies into the shape of a hose. Up to nine extruders are arranged in a ring and the individual flows of molten materials are combined in the spiral mandrel dies, allowing multi-layered films to be produced. The material is then stretched both horizontally and vertically in order to reduce the thickness of the molten tube down to the thicknesses commonly used today which are measured in hundredths of a millimetre. This is done by blowing in air centrally. The flow of air not only mechanically stretches the hose, but also cools it so that it sets into its shape. The film hose is calibrated through a basket, cut and rolled.
Blow moulding
The plasticized material is pressed through a ring-shaped nozzle to form a tube. The still plastic tube is pinched off by a two-part mould and blown using pressurised air. The hose becomes pressed to the mould and the blown part is ejected once cooled. This method is used for creating hollow products such as tubes, bottles, cannisters, barrels, etc.
B. Food industry – temperature control and cooling foodstuffs
Extrusion is at the centre of many the production processes used in the food and pet food sectors. We can provide you with the equipment you need for your processes. Alongside the plastics industry, the food industry is the main user of extruders. Extruders knead, mix, cook and portion food such as cereals, cornflakes, texturised proteins, vitaminised rice and pasta. To ensure that products remain consistent in terms of quality, consistency and flavour, precise and reproduceable temperature control is essential. Cooking processes need to be performed with perfect precision. Furthermore, there will often be several recipes that have to be switched between during production. Using hot extrusion, an aqueous material is heated under high pressure in a compression screw. The pressure drops off at the outlet nozzle and the product loosens up. Starch that has already gelatinised can support gas retention and hold on to solid pores. Typical products made using this method include peanut flips, snacks, various types of bread and baked goods.
C. Rubber industry
Rubber extrusion is a hot extrusion shaping process in which synthetic or natural rubber granules are pressed through a die to produce profiles, sealing materials, mats, etc.
D. Recycling
Special single or double screw extruders are used to turn clean and sorted plastic waste into recyclates (recycled material for creating new plastic products). The polymer unit is extremely important for achieving the high degree of quality required in this process. So that all contaminants within the plastic to be recycled can be removed, they are removed from the flowing molten material between the conveyor machine (extruder) and the extrusion die. Various separating techniques are often used in advance to ensure the purity of the material. Additives can be included during the extrusion process to improve the properties of the plastic.