Plastic injection molding is the ideal process for manufacturing plastic products across the world. Injection molds can be used to create a variation of products, from household cutlery to automotive parts to electronics and pocket combs, injection molds can be found almost everywhere. The injection process is ideal for those who want to produce a high volume of plastic products because multi-cavity injection molds can be created. There are many benefits of using injection molds, few are mention below.
An extensive range of material selection
Low labor costs
Nominal scrap losses
Injection Mold Machinery
Through the injection molding process, an injection molding machine, or press, must be used. The molds are tightly clamped to the platen of the machine, where the plastic is then injected to create an injection mold. Most presses are rated by tonnage, which is the calculation of the clamping force that the machine can exert. This is the force used to keep the mold closed during the injection molding process. Tonnage can often vary from less than five tons to 600 tons.
Nowadays, electric presses are taking over the old hydraulic injection molding machines. Most manufacturing companies prefer electric presses because they offer 80% less energy consumption and nearly 100% repeatability. It’s important to note that the rate of an electric molding machine is generally 30% higher than a hydraulic press.
The Mold Itself
Mold or die are the general terms used to describe the tooling used in plastic injection molding. In the earlier, injection molds were very expensive to manufacture, and they were only used when mass production was needed. Most molds are constructed from hardened steel, aluminum, pre-hardened steel, and beryllium-copper alloy. Whereas steel molds generally cost more to construct, they offer a longer lifespan. Pre-hardened steel injection molds incline to be less wear-resistant and they are used for lower volume requirements or larger components.
The Injection Molding Process
An injection molding machine contains of two main parts: the injection unit and the clamping unit. The vital steps of the injection molding process are as follows:
Clamping – The clamp unit consists of metal plates or platen. The initial process begins with the mould being clamped together under pressure. This accommodates the injection and cooling process.
Injection – This is when the molten thermoplastic material is injected under pressure into the mould through either or screw or ramming device.
Dwelling – Once the molten plastic has been injected into the mold, more pressure is exerted to make sure all of the mould’s spaces and cavities are filled.
Cooling – During the cooling process, the plastic is left to cool and solidify within the mould.
Opening – The movable platen is separated from the fixed platen to separate the new mould.
Ejection – Completed by the use of rods, a plate, or an air blast, the plastic component is completely removed from the mould.