Thermoplastics and thermosetting plastics are two separate classes of polymers that are widely used in the process of injection molding to create products of various types. Both these categories of plastics possess different properties and characteristics. Hence, choosing the right category of polymer, between the two, is of paramount importance to achieve the expected results when used in applications. Most of the injection molding service providers usually receive a question from their clients about the differences between thermoplastic and thermoset molding process. Here, in this post, let’s see thermoset & thermoplastic injection molding comparison.
Defining Thermoplastic and Thermosets
Before we go deeper into the topic, it is important to understand the two terms thermoset and thermoplastic. Let’s first find out what are thermosets and thermoplastics.
What are Thermosets?
Thermoset plastics “set” after they cure and are generally stronger than thermoplastic materials. Initially, the polymer is a liquid or soft solid, which becomes rigid later when cured. Owing to their high mechanical and physical strength, resistance to heat, corrosion, and mechanical creep, thermosets are used in a variety of applications. A few amongst the common thermoset materials used in the injection molding process include alkyds, epoxy, phenolic, polyimides, thermoset polyester, and so on.
What are Thermoplastics?
In contrast to thermoset, thermoplastics liquefy and become pliable when heat is applied. Thermoplastic polymers can be reheated and reprocessed many times, which is impossible when it comes to thermosets. Usually stored in the form of pellets prior to the molding process, these categories of polymers can withstand multiple re-shaping without causing any damage to the material. They possess high strength, shrink-resistance, flexibility, high-Impact resistance, and chemical resistant, among others. A few amongst the common thermoset materials used in the injection molding process include ABS, nylon, PET, polypropylene, polyethylene and TPE, among others.
Difference between Thermoset & Thermoplastic Injection Molding
The way thermosets are molded differs with respect to thermoplastics in several aspects and both the categories require varied treatment during the injection molding process. Let’s check a few differences when molding thermosets and thermoplastics.
Thermosets |
Thermoplastics |
Cold material is injected into an extremely hot mold to produce parts. |
Plastic material is melted and injected into a mold to produce parts. |
Form a permanent chemical bond. |
100% reversible as no chemical bonding takes place during the process. |
Can’t be remolded or reshaped |
Can be remolded and recycled |
Comparatively difficult to surface finish |
Injection molding using thermoplastics produces flexible, accurate and aesthetically pleasing surface finishes. |
Thermoset injection molding doesn’t require high heat and high pressure compared to the molding of thermoplastics. |
Thermoplastic injection molding demands high heat and high pressure. |
Prepared mostly by condensation polymerization. |
Prepared mostly by additional polymerization. |
Production process encompasses compression, transfer and casting. |
Production process involves injection molding, extrusion and blow molding. |
Example of products made from thermosetting injection molding include: Tool handles, billiard balls, sprockets, insulation, parts of computers, parts of TVs or any electronic equipment, gardening items, tools, cooking utensils |
Example of products made from thermoplastic injection molding include: Vacuum cleaners, kettles, toasters, toys, machine screws, gear wheels and power tool casings, packaging film, sacks and gas pipes and fittings. |
Disadvantages include: |
Disadvantages include: |
Now that you know how thermoset injection molding differs with respect to thermoplastic injection molding. With the information provided in the post, you would be able to make a judgment on the type of polymer category you should opt to produce molded parts. However, just knowing the differences between the materials won’t be enough, instead you would need an injection molding service provider who can mold your parts as per the right specifications provided. Partner with leading injection molding companies like Veejay Plastic who own a comprehensive working knowledge regarding thermoplastic vs thermoset molding.
