Injection moulding is one of the most widely used industrial production processes for melting plastic material and injecting it into a mould at high pressure, this is a brief description of this industrial process which we will now look at in more detail.
THE INJECTION MOULDING MACHINERY
There are different types of injection moulding machines, there are motorised machines, hydraulic machines, and hybrid machines that are driven by servomotor and hydraulic motor.
To try to understand the type of this type of machinery, one only has to think of a nozzle that injects the plastic material into the mould which has been previously heated, clearly then different plastics have different melting temperatures and different characteristics, but the principle of these machines is this.
On the nozzle side there is also a hopper which is used as a container for the material to be heated and the cylinder which is where the material is heated and then fed into the mould by the nozzle.
THE INJECTION MOULDING PROCESS
The injection moulding process is simple in concept, perhaps more complicated in execution, we need the product and the mould that will have been designed, tried, tested and changed, but it is very important that all steps in this process are perfect in order to create excellent end products.
First, the plastic material must be poured into the hopper, usually in granules, and the choice of material will be made according to the different characteristics that the final parts will have to have.
Once the granules are in the hopper, they are heated and melted inside the cylinder so that they are ready to be sent into the mould from the nozzle.
Once the plastic material is injected into the mould, it is allowed to cool so that it hardens and takes the exact shape of the mould.
The mould is opened and the part that has been moulded is removed from the mould and is ready for its use, whatever that may be.
There are more complex moulds that sometimes comprise several parts together, which is why the mould must be designed by specialists who are able to obtain precise moulds while avoiding as much waste and errors as possible, which on the production of many parts can be many.
When the product from the mould is taken out, it is cleaned and some parts that may be redundant such as the sprue are cut off.
INDUSTRIAL PLASTIC MOULDING
These induction moulding machines are made for industrial production, they are very bulky machines used to produce large quantities of parts in the shortest possible time and with the least possible waste.
The temperatures reached are very high and it would not be possible to achieve them with non-industrial machinery.
One of the main features of this injection moulding system is also economical, as it is possible to produce many parts and thanks to this the cost/unit is greatly reduced, but the possibility of modifying the production of the final product by changing the mould is also a considerable advantage.
Another important feature is the possibility of moulding in combination with metal inserts, as well as producing elements in different colours and materials. Today, the high precision of mould design (thanks to increasingly high-performance computers and programmes) allows the creation of very complex and sometimes multi-element products.
Today’s machines can produce parts with absolute precision and at a speed that seemed impossible before.
A minor cost flaw (which is mitigated, however, by industrial production of thousands of parts) the hot chamber can run into the thousands, which is why parts are produced for the automotive and packaging sectors. In fact, in these two sectors the parts needed are in the thousands, which justifies the costs.
