Thermoforming is a method of processing plastics, which is used in the production of packaging and other products for the needs of industry. Thanks to the mechanization of the production phases and the precise management of the individual stages of the technological process, the processing of thermoplastic plastics is as fast and precise as never before. Check how the forming of blanks is carried out and what machines are used for processing materials.
Thermoforming - what is it?
The processing of plastics by thermoforming consists in heating their surface above the yield point and then imprinting the material in a special form (reproduction of the inside) or on the hoof (reproduction of the outer part). Under the influence of stress, deformations occur, which are fixed during cooling. After that, the plastic is trimmed and becomes a finished product.
Thermoforming — what is it and what are its types?
During processing, only one side of the material is in contact with the mold. The mapping can therefore concern the outside of the mould (negative thermoforming) or the inside of the mould (positive thermoforming). Considering the way pressure affects the sheet, two types of thermoforming are distinguished - vacuum (deformation occurs with the help of vacuum) or pressure (vacuum replaced by compressed air). In both cases, negative or positive forms can be used.
How is thermoforming profes performed?
You already know what thermoforming is. So how does it work in practice? Let's trace the progress of the process using vacuum technology. The first stage of work is the placement of plastic for extrusion over the opening of the vacuum chamber. When the frame is lowered, the operator puts on it a set with heaters that heat the material from above. At the same time, air is pumped out of the vacuum chamber. When the plastic begins to collapse, the heaters are pushed back, and a table with a hoof or mold is introduced into the chamber. After the molding is complete, the operator turns on the fans that cool the product, and then detaches the finished products from the template. Removing the outer edges with a CNC milling machine allows you to give the workpiece the final shape.
What are some examples of thermoforming applications?
Thermal processing of plastics is used in many industrial industries. Thermoforming technology will prove itself in the production of packaging for food, components of equipment of motor vehicles, door linings of refrigeration equipment or covers of medical equipment. The application range of thermal molding is very wide. An additional advantage of this process is the possibility of using materials with different properties and parameters, which allows you to create parts that are even better adapted to the implementation of specific tasks.
What materials are used in thermoforming?
Thermoforming of plastics is a very flexible technology that will work well in individual and mass production. The possibility of implementing the process using a wide range of materials, offering different mechanical properties, is an undoubted advantage of this method of processing. Among the most commonly used raw materials are:
- Polystyrene — thermoforming polycarbonate is a relatively easy process due to the plasticity of the plastic. Polycarbonates are used in the production of packaging, cups or trays.
- ABS — thermoforming is very simple and not troublesome, because the material is characterized by high strength and rigidity.
- PMMA — is a material susceptible to mechanical and thermal treatment. Thermoforming plexi can be done with the use of extruded plates (cheaper) or sheets poured into molds.
Thermoforming plastic is one of the most frequently implemented technological processes, which does not mean that heat treatment does not include other materials as well. It is equally common, for example, thermoforming of felt, that is, a material made of processed natural or artificial wool.
What tools are used in thermoforming?
Heat treatment requires the use of specialized equipment. Depending on the scale of the activity, thermoforming lines with one, two or three stations are used. If a single station line is used, the plastic is under the same machine at all times. The use of more stations allows you to streamline work and increase production efficiency. This is especially important in enterprises where work is carried out with high intensity.
Molds
The basic element used in the thermal molding process is a thermoforming mold also called a die or template. What exactly are molds for? Thermoforming is a process that aims to give objects the desired shape. When heated, the plastic sheet becomes flexible and conforms to the mold, which allows you to achieve a strictly defined appearance of the final product.
Heaters
You know how vacuum thermoforming works. So let's look at the key process, which is the heating of the raw material. The machines used in this process are called thermoformers. Heating plates, equipped with heaters, are used to heat plastics from below and above (at the same time). The heater control software and the zone temperature control are responsible for heating the material. Part of the heaters (controlling thermoforming heaters) has built-in elements that are responsible for zoned temperature monitoring. At the same time, bilateral heating of the processed plates occurs. The power of the heaters, which are located in the lower part, is on average 40% less. Thanks to the use of high-tech solutions, the time between heating the plastic to a given temperature and the start of forming the product is reduced to a minimum.
Also check out: Ring heaters
In vacuum thermoforming machines, contactless (ceramic, quartz, halogen) or conductive-based (contact heaters) heaters are used. Heating can take place anywhere, provided that the semi-finished product will have a suitable temperature. The time between the end of heating and the beginning of the molding should therefore be as short as possible.
So which thermoforming heaters will be the best? You need to know that by using halogen heating elements, you can reduce the heating time by up to half. These types of heaters will work for all materials used during heat treatment processes. Of particular note is the low absorption of the wavelength, which allows the penetration of radiation and gives the possibility of uniform heating of even very thick elements.
Read more: Heating spirals
Thermoforming with Sinkoplex heaters
In the offer of the manufacturer Sinkoplex you will find a wide range of heaters designed for thermoformers. Their special design allows a large amount of heat to be emitted. Thanks to the use of coking technology, which causes a high concentration of magnesium oxide and significantly improves the parameters of the heating elements, the heaters can maintain compact dimensions without the risk of loss of performance.
If you are looking for high-quality spare parts for thermoformers, be sure to check out Sinkoplex's offer. For any questions, we cordially invite you to contact us by phone or e-mail.
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