Before we study the devices used in injection molding, we must know about injection molding.
What is Injection molding?
This process involves the insertion of molten plastic material under extreme pressure into a mold cavity. In finally shaped into the desired forms when the material is then allowed to cool. The period of the injection molding cycle ranges from a few seconds to 2 or more minutes. But it depends upon the size, design, complexity, and material of the parts.
What is Injection Molding Manufacturing in the First Part?
At First Part, we manufacture high-quality plastic molded parts for defense, medical, aerospace, and automotive worldwide.
Process of Plastic injection molding in the First Part?
The process of plastic injection molding in the First Part includes the following stages.
1. Devising the Material:
Dry plastic pellets are mixed with color additives or fillers.
2. Loading of Pellets:
Molding machines carry pellets into their hopper, and then these pellets are sent to the mold cavity in the barrel with the help of a screw.
3. Heating the Pellets:
In the barrel, the pellets undergo a heating process for melting. It also warms the mold cavity.
4. Insertion of Molten Plastic Material:
The heated mold or die cavity is filled with molten liquid or resin through an opening called a gate. The molten material, after filling into the cavity, converts into the mold form.
5. Cooling the Mold Material:
The molten material in the mold and the mold itself are allowed to chill to take a solid form.
6. Ejecting the Solid Material:
The cooled and solidified material is brought out into the loading cabin through the gate of the mold cavity. Ejector removes the mold material from the mold cavity, and a new injection molding cycle is ready to start now.
Injection Molding Machine:
It is also called injection press and used to produce plastic product parts through the process of injection molding. It consists of two main parts.
- Injection unit
- Clamping unit
1. Injection Unit:
It further comprises three main components, which are as follows.
- Heaters, Thermocouple, and Ring plunger.
- Screw motor
- Reversing screw and a barrel.
2. Clamping Unit:
The clamping unit consists of the following components.
- Motor drive
- Tie brass
Working of Injection Molding Machine:
Injection molding machine molds are locked vertically or horizontally. Most of the machines are set into a horizontal position, but the machine’s vertical role in insert molding and other processes benefit from the gravitational force. Some vertical molds can perform their tasks without fastening.
For rapid tool fluctuations, magnetic and hydraulic clamps are used. The designers must know about the mold, whether it requires a cold runner system or a hot runner system. It is necessary to pour the molten plastic material and fillers into the mold cavities.
A cold runner system is quietly incised into the mold cavity. The plastic-filled into this mold became cool down and brought out with the part as a sprue.
On the other hand, a hot runner system is intricate and employs cartridge heaters to retain the plastic in the runner warm with the cooling of the parts. After bringing out the amount, the plastic residue in the hot runner system is inserted into the upcoming product part.
Types of Injection Molding Machines:
The following machines or systems are involved in the injection molding manufacturing process.
- Hydraulic machine
- Mechanical Machine
- Electrical Machine
1. Hydraulic Machine:
This conventional system has been only a choice to mold designers. At last, Nessie Plastic Industrial Co. Limited launched its first electric injection molding machine in 1983. The hydraulic machine is one of the most popular systems in the world to make injection-molded parts.
2. Mechanical Machine:
It uses a toggle system to build up tonnage. Tonnage is the most important necessity of machines to withstand the injection pressure. The clamping side of the device remains closed (tool half fastened on platen). The plastic products will be produced by opening tool half.
3. Electrical Machine:
It is also referred to as Electric Machine Technology or electric press. It is an economic system due to the less consumption of electricity. It is also an environment-friendly system to reduce pollution. It possesses a rapid production rate with high-precision, but it may be unaffordable for middle-class people.
Some people believe that hybrid injection or Servo-Hybrid consumes less energy as compared to hydraulic and electric systems. But in fact, it requires a similar quantity of energy as hydraulic and electric systems do. The power expenditure depends on the size, complexity, and geometry of the part being manufactured.
The molded components are extracted from the molds by a robotic arm into the container.