Thermoforming and blow molding lines are used to produce plastic items or hollow plastic parts. The technology is different for every type of the lines. In this article we will look into each of them and discuss their advantages and disadvantages.
Thermoforming
With thermoforming lines you can easily produce goods like cups, food packaging or automobile parts. The equipment is suitable for both large and small items. Productivity depends on the size of the machine, mold and the produced items. If we talk about large industrial lines, their capacity may reach thousands of finished items per hour.
Usually a plastic sheet is used as an input material. It can be made out of polyethylene (PE), polypropylene (PP), polystyrene (PS) or polyethylene terephthalate (PET). It also can be of a variable thickness and color. If a thermoforming line is connected to an extrusion line, the plastic sheet is fed right from the extruder. The sheet is heated and formed to a desirable shape in a mold using either air, vacuum pressure or both. Then the shape is trimmed in order to create a product. A sheet web remains after the parts are trimmed. It is normally collected and fed into a crusher for recycling and further use in the production process. Another option is to sell the sheet web to reprocessing companies.
Thermoforming lines are the least expensive when comparing to injection, blow molding or compression lines. In particular, the mold is usually made out of aluminum which doesn’t cost much. This great advantage makes thermoforming lines a perfect choice for low-volume production or prototype development.
Another important advantage is that the mold can be designed to meet specific needs of the client. The process is very flexible, so with one line you can produce a variety of goods.
Blow molding
The process of blow molding is very similar to a glassblowing. Its mass production was first set in 1939 in the United States and has been gaining popularity ever since.
With blow molding lines you can produce a large variety of small and medium plastic items, e.g. PET bottles, milk bottles, fuel tanks etc. This manufacturing process is perfectly suited for mass production as the lines work fast and efficiently. They also ensure a uniform wall thickness.
An extrusion blow molding process starts with heating up the plastic. Then machines inject air blowing up the material into a mold in which plastic expands taking the shape of the mold. The final step is cooling the plastic and ejecting it.
With a multilayer blow molding machine it is possible to produce plastic containers that can be heat resistant, non-toxic, impact resistant or anti-bacterial. These qualities are reached by the usage of two or more layers of plastic. It can be the same type or different types of the polymer, e.g. nylon, PVC, PE, polyvinyl alcohol, polyolefin etc. The layers are injected into a blow molding machine and a parison is formed by a nose.
Extrusion blow molding is the most commonly used type as it has many advantages like low tool cost, high efficiency and ability to manufacture complex items. On the other hand, with blow molding lines you cannot mold anything other than hollow products or parts.
BOMAC Industries strives to provide innovative solutions for recycling plastics and offers a wide range of plastic recycling lines and machines for most common plastics and rubber, for example PET bottles, plastic film, car tires, PVC profiles etc.
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