What are Thermosets and Thermoplastics | Difference Between Thermosets and Thermoplastics | CNCLATHING


When choosing a material for CNC machining services, engineers and manufacturers often consider mechanical properties of the metal or plastic and its cost-effectiveness. As wide used polymers materials, what are thermosets and thermoplastics and what’s the difference between them? 

What are Thermosets?

Thermosets, refers to the thermoset plastics, or thermoset composites, are synthetic materials that strengthen when heated. Before forming, thermosetting plastics have the same chain structure as thermoplastics. In the forming process, thermoset plastics react by thermal or chemical polymerization to form a cross-linking structure. Once the reaction is complete, thermosets become immiscible, insoluble solids. If there is no cracking, it can not be softened or reprocessed even with the heat. Thermoset plastics have resistance to high operating temperatures, corrosion, and chemicals, good mechanical strength and dimensional stability. Many thermoset plastics are engineering plastics.

Types of Thermosets

– Polyester

– Vinyl Ester

– Polyimides

– Polyurethanes

– Polyureas

– Structural Foams

– Epoxies

– Melamine

– Silicone

– Urea Formaldehyde

– Phenol formaldehyde

What are Thermoplastics?

Thermoplastic, also referred to as thermosoftening plastic, is a plastic polymer material that has plasticity or become moldable at a certain elevated temperature and solidifies upon cooling, and can repeat this process. Thermoplastic is one of the most widely used plastics, which is mainly made up of thermoplastic resin and various additives. At a certain temperature, the plastic can be softened or melted into any shape, and maintain the shape after cooling. Lots of thermoplastics are common materials in CNC milling and turning. 

Types of Thermoplastics

– Acrylic (PMMA,  poly(methyl methacrylate))

– Acrylonitrile butadiene styrene (ABS)

– Polyamides (Nylon)

– Polylactic acid (PLA)

– Polybenzimidazole (PBI)

– Polycarbonate (PC)

– Polyether sulfone (PES)

– Polyoxymethylene (POM)

– Polyetherether ketone (PEEK)

– Polyetherimide (PEI)

– Polyethylene (PE)

– Polyphenylene oxide (PPO)

– Polyphenylene sulfide (PPS)

– Polypropylene (PP)

– Polystyrene (PS)

– Polyvinyl chloride (PVC)

– Polyvinylidene fluoride (PVDF)

– Teflon (PTFE)

CNClathing.com is specialized in an extensive range of drilling/turning/milling plastic services, such as Nylon CNC machining, ABS CNC machining, PC CNC machining, etc.

Difference Between Thermosets and Thermoplastics

Due to the differences between thermoplastics and thermosets, including properties, structure, cost, uses, and more, they are applied to different areas or made into certain plastic products. 

1. Chemical structure

Thermosets have cross-linked molecular chains, while thermoplastics are made up of linear molecular chains.


2. Curing process

The curing process of thermosets is irreversible and the formed plastic can’t be reprocessed and reshaped, while the curing process of thermoplastics is completely reversible, there is no chemical bonding take place, and the plastic can be melted and softened again with heat.


3. Recyclability

Thermoplastics can be remolded and recycled at certain temperature without negatively affecting the material’s physical properties, so it’s highly recyclable, but thermosets can’t be recycled.


4. Application

As more resistant to high temperatures, thermosets plastics are ideal for applications with  extreme low/high temperatures and sealed products like electronics and appliances. While thermoplastics have low melting points and often serves low-stress applications like plastic bags or high-stress mechanical parts.



Thermoplastics are generally more expensive than thermoset.


6. Injection molding feasibility

Injection molding utilizing thermosetting polymers can use less heat and pressure, which is more cost-effective and time-efficient than thermoplastics.