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Know about Injection Molding: Parts and Processes

by Josh Biggs in Tech on 27th February 2023

Injection molding is a process in which different products are made using a plastic injection machine. This is achievable by using the required force to develop a finished product. Injection molding Is used to introduce new product designs for different applications.

Injection molding is a manufacturing process that produces items quickly and consistently. Injection molding is done with the use of raw plastic pellets and other materials, including metals

Parts of Injection Molding machine:

The injection molding machine consists of the following parts:

  • Hopper
  • Screw motion
  • Heaters
  • Nozzle
  • Extraction Pin
  • Split Molds
  • Clamping Unit
  • Injection Unit
  • Drive unit
  • Hydraulic Unit

Injection molding process step by step:

Below is the process of injection molding:

  • Plastic materials are fed into a hopper then from the hopped; it goes into the barrel of the machine.
  • There’s a reciprocating screw whose function is to rotate and push the plastic material forward.
  • The material then goes to the area where it gets heated and turns into molten plastic.
  • Then the molten material is fed into the mold through a nozzle.
  • The molten plastic is left for a while to cool and take the shape of the mold.
  • After the cooling process, the product is ejected from the mold using an extraction pin
  • Through this process, you can make different products like 

Types of injection moldings

  • Metal injection molding
  • Die casting
  • Injection molding of liquid silicone rubber
  • Thin-wall injection molding
  • Reaction injection molding

Below is a brief description of each of these injection moldings.

Metal Injection Molding 

This process involves mixing metal powder with the plastic material powder and then producing the feedstock. Then this feedstock goes through the injection unit into an already-designed cavity. The feedstock is poured into the cavity, and the end product is the “green” mold metal part.

The cavity size is usually more oversized than the expected shape because the mold metal may shrink after the cooling process. That’s why there’s provision for extra space. After this process, the plastic binding powder is separated from the metal part; to achieve this, the metal part is heated or dissolved in a chemical composition.

The following metals are used for this process

  • Low alloy steels
  • Stainless steels
  • High-speed steels
  • Irons
  • Cobalt alloys
  • Copper alloys
  • Nickel alloys
  • Tungsten alloys
  • Titanium alloys

Die Casting

Through the die-casting process, a product can achieve a perfect dimensional and accurate surface finish. This process entails pouring the molten metal into the die to achieve the desired shape.

  • Die casting is done by two methods:
  • Die-casting hot chamber

These alloys are mainly used for die casting:

  • Zinc
  • Aluminum
  • Magnesium
  • Copper
  • Lead
  • Tin

Injection Molding of Liquid Silicone Rubber

Durable materials can be produced through this process.

Thin-Wall Injection Molding

This molding process can be applied when thin plastic parts are needed to be produced to reduce the production cost compared to using another molding process. This molding process is mainly used to make medical devices, cooking equipment, etc.

Reaction Injection Molding

This process involves mixing two types of material at high pressure into a mixer and then pour into the mold at low pressure.

Categories: Tech