Is Injection Molding for Thermoset or Thermoplastic?

Injection molding is used for both thermoset and thermoplastic materials, each offering distinct advantages and applications depending on the project requirements.

Is Injection Molding for Thermoset or Thermoplastic?

Injection Molding Process

The injection molding process is a common method used for manufacturing various plastic parts. This technique is highly efficient, scalable, and suitable for producing high-volume, complex components.


The core concept of injection molding revolves around injecting a melted plastic material into a mold cavity. After cooling, the material solidifies into the shape of the cavity, creating a part or component. The process involves several steps, each contributing to the overall efficiency and quality of the molded parts.

Steps Involved

  1. Material Preparation: The chosen plastic material, usually in the form of pellets, is loaded into the injection molding machine.
  2. Melting: A screw mechanism pushes the plastic pellets into a heating chamber, where they melt into a liquid form.
  3. Injection: The melted plastic is then injected into the mold cavity using high pressure.
  4. Cooling: Once the material fills the mold, it starts to cool and solidify, taking the shape of the mold.
  5. Ejection: After cooling, the newly formed part is ejected from the mold, and the process is repeated for the next cycle.

For more details, you may refer to the Wikipedia article on Injection Molding.

Machine Components

  • Hopper: The hopper is where the plastic pellets are initially loaded.
  • Heating Chamber: This is where the pellets are melted. It is crucial to maintain an optimal temperature for different materials.
  • Screw Mechanism: This part pushes the melted plastic into the mold. It also plays a role in mixing and heating the material.
  • Mold: The mold is a metal piece with a cavity shaped as the desired part. It can be a single cavity or multi-cavity, depending on the production needs.
  • Ejector System: After the cooling phase, the ejector system pushes the part out of the mold.


Thermoset Injection Molding

Thermoset injection molding is a process used for creating parts and components from thermosetting plastics. Unlike thermoplastics, thermosets form irreversible chemical bonds when cured, providing certain advantages such as high thermal stability and resistance to solvents. Below are the characteristics, applications, and pros and cons of thermoset injection molding.


  • Irreversible Bonding: Once cured, thermoset plastics cannot be remelted or reprocessed.
  • Thermal Stability: These materials can withstand higher temperatures without losing their structural integrity.
  • Chemical Resistance: Thermosets are generally resistant to solvents, making them ideal for harsh chemical environments.


  • Automotive: Due to their high thermal and chemical resistance, thermosets are used in under-the-hood components in cars.
  • Electrical Components: Used in circuit boards and other electrical assemblies due to their insulating properties.
  • Industrial: Various mechanical parts such as gears and housings are made of thermosets due to their durability.

Here’s a useful link to Wikipedia’s page on Injection Molding to explore how thermoset materials are commonly used.

Advantages and Disadvantages


  • Durability: Thermosets are known for their long-lasting nature, especially under stressful conditions.
  • Cost-Effective: Generally cheaper to produce in high volumes.



  • Non-Recyclable: Once set, thermosets can’t be remelted for reuse, contributing to waste.
  • Limited Flexibility: The curing process limits the kinds of shapes and sizes you can produce with thermosets.

Thermoplastic Injection Molding

Thermoplastic injection molding is a widely used manufacturing process that produces parts from thermoplastic materials. These materials differ from thermosetting plastics in that they can be melted, solidified, and then remelted without undergoing any significant chemical change. This article outlines the characteristics, common applications, and advantages and disadvantages of thermoplastic injection molding.


  • Reusability: Thermoplastic materials can be remelted and reused, allowing for more sustainable manufacturing practices.
  • Ease of Processing: Generally easier to mold than thermosetting plastics, offering a broader range of design possibilities.
  • Strength and Flexibility: Many thermoplastics offer a good balance of mechanical strength and flexibility, allowing them to be used in a diverse array of applications.

To know more about thermoplastic properties, you might find this Wikipedia article on Thermoplastic useful.


  • Medical Devices: Commonly used in syringes, tubes, and other single-use medical equipment.
  • Consumer Electronics: Used in the casings of smartphones, laptops, and other gadgets.
  • Packaging: Widely used in creating various types of packaging materials due to its moldability and cost-effectiveness.

For more on applications, you can refer to Wikipedia’s section on Injection Molding.

Advantages and Disadvantages


  • Versatility: Suitable for a wide range of applications due to its ease of processing.
  • Recyclability: These materials can be recycled, reducing waste and environmental impact.


  • Lower Thermal Resistance: Generally, thermoplastics are not as heat-resistant as thermosetting plastics, making them unsuitable for some high-temperature applications.
  • Cost: Some high-performance thermoplastics can be more expensive than their thermosetting counterparts.

Comparison between Thermoset and Thermoplastic Injection Molding

Characteristic Thermoset Plastics Thermoplastic Plastics
Reusability ❌ Cannot be remelted ✔️ Can be remelted and reused
Thermal Resistance ✔️ High heat resistance ❌ Lower heat resistance
Chemical Resistance ✔️ Resistant to many solvents ❌ May be less resistant
Material Cost ✔️ Generally cheaper ❌ Can be more expensive
Production Speed ❌ Slower due to curing time ✔️ Faster cycle times
Design Flexibility ❌ Limited due to curing ✔️ More flexible
Part Complexity ❌ More difficult for complex parts ✔️ Easier for complex geometries
Recyclability ❌ Non-recyclable ✔️ Recyclable
Environmental Impact ❌ Higher waste ✔️ Lower waste due to recyclability

Industry Examples

Injection molding finds applications across various industries due to its versatile capabilities. Below are some examples of industries where both thermoset and thermoplastic injection molding play a crucial role.

Automotive Industry

  • Dashboard Components: Injection molding produces various parts of a car’s dashboard, such as knobs and dials.
  • Under-the-Hood Components: Items like air filters and coolant reservoirs often come from injection molding processes.
  • Interior Parts: Door handles, seat adjusters, and other interior car components are also made using injection molding.

Medical Industry

  • Syringes: One of the most common uses of injection molding in the medical industry is the production of disposable syringes.
  • Medical Implants: Some types of biocompatible medical implants are made using injection molding techniques.
  • Surgical Instruments: Many disposable surgical tools like scalpel handles and specula are produced using injection molding.

Consumer Electronics

  • Smartphone Cases: Injection molding is commonly used to create a variety of smartphone cases.
  • Remote Controls: The plastic components of TV and air conditioner remote controls are often made via injection molding.
  • Computer Components: Parts like keycaps, chassis, and even circuit board components can be produced through injection molding.

Scroll to Top