An Injection molding machine, also known as an injection press, is a machine for manufacturing plastic products by the injection molding process.
It consists of free main parts, an injection unit, a clamping unit and the frame to support them.
Construction of injection molding machines
There are 3 big parts every injection molding machine will have: Clamping Unit, Injection Unit and the Frame.
Here are main parts of the clamping unit for your information:
The drawing of the injection molding machines` clamping unit:
And the frame`s construction details as well for you to help you understand it:
Types of injection molding machines
Machines are classified primarily by the type of driving systems they use: hydraulic, mechanical, electric, or hybrid.
Hydraulic Injection Molding Machines
Hydraulic injection molding machines have historically been the only option available to molders until Nissei Plastic Industrial Co., LTD introduced the first all-electric injection molding machine in 1983.
Now in used injection molding machines are mostly hydraulic driven. And the precision is getting more and more higher. Due closed loop control system is used and putting the feedback unit near the end of required units.
Mechanical Injection Molding Machines
Mechanical type machines use the toggle system for building up tonnage on the clamp side of the machine. Tonnage is required on all machines so that the clamp side of the machine does not open (i.e. tool half mounted on the platen) due to the injection pressure. If the tool half opens up it will create flash in the plastic product.
Electric Injection Molding Machines
The electric press, also known as Electric Machine Technology (EMT), reduces operation costs by cutting energy consumption and also addresses some of the environmental concerns surrounding the hydraulic press. Electric presses have been shown to be quieter, faster, and have a higher accuracy, however the machines are more expensive.
Hybrid injection (sometimes referred to as “Servo-Hydraulic”) molding machines claim to take advantage of the best features of both hydraulic and electric systems, but in actuality use almost the same amount of electricity to operate as an electric injection molding machine depending on the manufacturer.
A robotic arm is often used to remove the molded components; either by side or top entry, but it is more common for parts to drop out of the mold, through a chute and into a container.
Above types are named by the driven system working methods. And here is another calling with there construction styles:
Vertical injection molding machine and horizontal injection molding machine
Vertical style mean the mold open and close direction is vertical with injection direction. Please check below picture to help you understand for it.
Horizontal style of course means the are paralleled. It`s much easier to understand while you know what the vertical molding machine is. Here we attached one of our dedicated injection molding machine for your reference:
Operation of injection molding machines
Injection molding machines can fasten the molds in either a horizontal or vertical position. The majority of machines are horizontally oriented, but vertical machines are used in some niche applications such as insert molding, allowing the machine to take advantage of gravity. Some vertical machines also don’t require the mold to be fastened. There are many ways to fasten the tools to the platens, the most common being manual clamps (both halves are bolted to the platens); however hydraulic clamps (chocks are used to hold the tool in place) and magnetic clamps are also used. The magnetic and hydraulic clamps are used where fast tool changes are required.
The person designing the mold chooses whether the mold uses a cold runner system or a hot runner system to carry the plastic from the injection unit to the cavities. A cold runner is a simple channel carved into the mold. The plastic that fills the cold runner cools as the part cools and is then ejected with the part as a sprue. A hot runner system is more complicated, often using cartridge heaters to keep the plastic in the runners hot as the part cools. After the part is ejected, the plastic remaining in a hot runner is injected into the next part.
Some content was quote on Wikipedia.