Plastic moulding: what it is and how it works

Brief introductory guide to plastic moulding

In the field of industrial processing, plastics, together with metals, are the most widely used materials. For both materials, production processes are carried out using specific machinery, suitable in terms of characteristics and functionality to work with plastic or metal. The objective of the processing is to obtain a piece ready to be finished or destined for a subsequent transformation stage.
The industrial processing of plastics, in particular, is moulding.

What is plastic molding

Plastic moulding is a production technology used for the manufacturing of plastic components through the use of custom-designed plastic moulds. This has taken on primary importance in the manufacturing industry, especially in recent decades, due to the ever-increasing demand for finished plastic products and the need for hardware for precision processing.

Increasingly advanced technologies have enabled a decisive evolution of moulding, which today allows the production of the most diverse products and components in polymeric material thanks to increasingly sophisticated plastic moulding tools.

Let’s look in more detail at how the industrial plastic moulding process works. First of all, it owes its name to the fact that the procedure involves the use of a mould.

There are different ways to carry out the moulding process, depending on how the plastic material is processed and the type of object to be obtained: each particular type of polymer has specific processing conditions, including:

• moulding temperature, which ranges between 165 and 360 degrees;
• mould temperature, which is generally between 20 and 140 degrees. However, PTFE worked in moulds at temperatures between 200 and 230 degrees is an exception

In general, the technique of “plastic moulding” means any industrial processing process that allows a plastic material object to be shaped by means of moulds for plastics in order to obtain either a finished object or a subsequent processing step.

It is a technique widely used at industrial level (as Beschi does) and finds application in a wide range of sectors. Think of how many plastic material objects (vinyl, polymers and others) are made by many different manufacturing companies: textile accessories such as those produced by Beschi, household appliances, high-tech products, automotive, communications and much more.

These are processes that evolve considerably over time, thanks to changes in machinery and the evolution of industrial plastic moulds, to the advantage of the variety of shapes, designs and applications.

The different types of plastic moulding

Based on how the starting plastic material is processed, and the way in which it is transferred into the moulds, the moulding process can be carried out in different ways.

It is a technique that can only be carried out with the use of professional equipment dedicated to specific processing – especially presses or more complex moulding systems. These machines, together with precision plastic molds, are essential to carry out processing that is absolutely precise and of high quality.

The main industrial plastic moulding techniques are:

• Injection moulding: it is one of the main and most widely used industrial moulding methods for plastics. In this technique, the plastic material is injected into plastic injection moulds by means of an injection module. This heats the material until it reaches a viscous state, so that it can be pushed into the mould, which in turn is kept closed by a hydraulic or mechanical system. In the RMI variant (Reaction Injection Moulding), two fractions of liquid plastic are used, destined to be first mixed and then directed into an aluminium mould. Here polymerization occurs, i.e. the hardening of the compound. It is a process that requires precise control of the mould temperature, so that the solidification process takes place correctly.
• Compression moulding: it exploits the principle of vulcanization: the plastic material is first prepared (divided into parts of the ideal weight or size) and then inserted into the machine. “Compression” involves the material being lowered into a heated aluminium mould. Then, a part based on sulphur and additives is added, which makes the plastic more malleable and easy to shape in the mould. Finally, the shape of the object to be made is impressed.
• Blow moulding: it is a technique mainly aimed at making hollow objects. The molten plastic material is inserted into a mould; then, air is blown in, so as to push the polymer (not yet solidified) to adhere perfectly to the walls of the mould.
• Thermoforming: with this technique, sheets or films of plastic material are shaped. These are laid on a mould to obtain an object of the defined shape. The process can be carried out starting from preheated sheets or films compressed on a mould with an air system that also facilitates cooling.
• Rotational moulding: it is mainly used to make large objects. The plastic material is inserted into a special mould (aluminium or composite material). This is rotated and heated: the polymer becomes viscous and is distributed along the internal walls of the mould, until it takes its shape.
• Foam moulding: expanded materials (generally foams) are used to create structures of even very small dimensions.

Prospects and future materials for plastic moulding

The injection molding technique was invented in 1872. The injection moulding technique was invented in 1872. The type of technique has obviously changed greatly and evolved strongly over time, as have the type and variety of materials adopted and the plastic moulds used. The process is now more than consolidated and mature. This does not mean that changes and evolutions have ended, on the contrary. Great innovations are coming in the next few years.

First of all, the ever-increasing attention to environmental sustainability. The need to reduce the impact of production processes on the planet is leading to increasing research and adoption of bioplastics and recycled plastics. Materials with low environmental impact, but which still present criticalities that will need to be resolved. Bioplastics are sensitive to degradation and need precise control of process parameters to avoid this phenomenon. Recycled plastics, on the other hand, may contain impurities that can make cleaning and maintenance of machinery more frequent.

Another major change underway concerns the integration of the Industrial Internet of Things (IIoT) and artificial intelligence with 5G technologies to enable real-time monitoring and optimization of production processes.

Since 1972, Beschi SRL has specialized in plastic moulding and in the design of moulds for plastics, especially in the production of plastic accessories for the textile industry and metal furniture accessories. Made in Italy production expresses the excellence of creativity and craftsmanship that create superior quality products through plastic moulding techniques carried out at the highest levels, with an eye to sustainability and innovation.

In fact, advanced production and design techniques for plastic moulding tools, together with the search for ever greater sustainability, have made it possible to create products that satisfy the highest functional and aesthetic requirements, while reducing their environmental impact.