The manufacturing processes of plastics

In this article, we tell you about 2 manufacturing processes that are used with plastics, e.g. what is needed for them and how they are carried out.

Extrusion

In the world of industrial plastics manufacturing, extrusion plays a decisive role. This process enables the efficient production of plastic products in various shapes and sizes, from pipes and profiles through to films and sheets. But what exactly lies behind this fascinating process?

What is extrusion?

Extrusion is a continuous manufacturing process in which a thermoplastic plastic is pressed through a die to obtain a specific shape. The material is first heated to make it malleable and then pressed through a nozzle or a die to obtain the desired shape.

This process can be used both for mass production and for the manufacture of individual parts.

The steps of the extrusion process:

• Material preparation: The first step is to prepare the plastic in the form of granules, powder or pellets. Depending on the properties of the end product, additives such as colourants, stabilisers or reinforcing agents can also be added to the plastic.
• Melting and homogenising: The prepared material is fed into an extruder, where it is melted and homogenised by heat and mechanical movement. The extruder consists of a screw that continuously presses the material through a heated chamber.
• Shaping: After the plastic has melted, it is pressed through a nozzle or a die to obtain the desired shape. This shape can comprise a wide variety of geometries, including tubes, profiles, films or sheets.
• Cooling and curing: Once the plastic has reached the desired shape, it is stabilised by cooling or curing. This can be done by air cooling, water bath or special cooling rollers, depending on the requirements of the end product.
• Post-processing: In some cases, the extruded material can be subjected to further post-processing processes, such as cutting to the desired length, punching holes or applying surface coatings.

Applications of extrusion:

Extrusion is used in a wide variety of industries and enables the manufacture of a broad range of products, including:

• Pipes and hoses: Used in the construction industry, agriculture, the automotive sector and many other areas.
• Profiles: For example window and door profiles, trim strips and railings.
• Films and packaging: For food packaging, construction films and other applications.
• Sheets and films: Used in the manufacture of displays, signs, advertising boards and much more.

Injection moulding

In today's world, plastics are ubiquitous. From our mobile phones through packaging to medical devices – they play a decisive role in our daily lives. But how are these versatile materials created?

One of the most common manufacturing processes is injection moulding, which makes it possible to produce complex shapes with high precision and efficiency. Let us take a closer look at how this process works.

The material

First, we need the right material. Plastics come in various forms and compositions, which are selected according to the requirements of the end product. These materials are often in the form of granules or pellets and can have various properties such as flexibility, hardness, colour and chemical resistance.

The tool

The key to the injection moulding process is the tool, also known as the injection mould or injection moulding tool. This mould typically consists of two halves that can be joined together and have a cavity structure that corresponds to the desired shape of the end product. The cavities are traversed by a complex network of channels that make it possible to inject the molten material and allow air to escape.

The process

The actual injection moulding process begins with heating the plastic material to the required temperature until it reaches a molten state. The molten material is then injected into the injection mould. This takes place under high pressure to ensure that the material fills every corner and edge of the mould and air bubbles are avoided.

The cooling

Once the mould is completely filled, the material is left in the mould until it has cooled sufficiently and has assumed a solid structure. The cooling time depends on various factors, including the thickness of the part and the type of material used.

Demoulding

Once the material has cooled, the mould halves are opened, and the finished part is removed. This step often requires the use of demoulding mechanisms such as ejectors to ensure that the part is released smoothly from the mould without causing damage.

Post-processing

Depending on the requirements of the end product, post-processing may be necessary. This can include removing excess material, polishing surfaces or adding threads or other features.