5 applications of thermoset resins

5 applications of thermoset resins

Thermoset resins are among the toughest materials in the world of plastics. They are ideal for applications that require dimensional stability, high heat resistance, electrical insulating properties, corrosion resistance and creep resistance. They are also frequently used to replace metal because they combine exceptional toughness with light weight.

But many engineers aren’t aware of what thermoset resins are and the applications where they work best. This helpful guide will provide you with an overview of five industries where thermoset parts are being successfully used, along with examples of parts Ci-Dell has produced for each one:

  • Electrical Insulation / Power Distribution
  • Food service
  • Agriculture
  • Aerospace
  • Lab equipment

What are thermoset materials?

They are made of polymer resins that are cured through a heat and chemical cross-linking process. This curing process transforms the resin into its final form. Once the cross-linking has taken place, the material cannot be melted or re-shaped. 

Thermoset materials are generally stronger than thermoplastic materials and are better suited to high-temperature and high-strength applications than many other types of plastics. Their dimensional stability is ideal for applications where other types of plastics may tend to “creep” under high heat conditions. Thermoset materials are an excellent candidate for products being considered for metal replacement.

Electrical / Power Distribution

Parts used in electrical and power distribution must have excellent dielectric strength. In other words, they’re great insulators. Depending upon the application, dimensional stability and high heat and corrosion resistance are also desirable properties.


Sealed limit switch housing

  • Applications: Material handling, packaging, food processing and transportation – ideal for wet environments and wash-down applications
  • Material used: Diallyl phthalate – long glass-filled DAP
  • Requirements: Corrosion resistance for prolonged exposure to salt water & corrosive chemicals while retaining dimensional stability to prevent leaks

Large switch lever for transformer actuator

  • Application: Used to regulate the voltage at electrical substations
  • Material used: BMC – glass-filled wet polyester
  • Requirements: Thermal stability and mechanical strength

Insulator for dynamic braking systems

  • Application: Dynamic braking takes energy generated by wheel motors on locomotives and large mining trucks and passes it through large resistor grids. This slows them down. This part is used to hold the wires that dissipate the heat from dynamic braking. 
  • Material used: BMC – glass-filled wet polyester.
  • Requirements: Excellent heat and ignition resistance and dielectric (insulating) properties.

Food Service

Many parts produced from thermoset resin are used in public-facing applications. That means a smooth, glossy finish is a must. They must also be resistant to oils from human hands and acidic food products. Depending upon the application, heat resistance may also be desirable.


Pump knob

  • Application: These knobs are used to dispense catsup, mustard and other liquids at restaurants, coffee shops and large entertainment venues. In this application, a high gloss finish and dense material convey that this is a high-quality, durable part.
  • Materials used: Glass-filled polyester, melamine or phenolic.
  • Requirements: Resistance to oils and acidic food products, such as catsup.

Sanitizer shroud

  • Application: This plastic container surrounds a heated metal canister used to sanitize utensils on food buffets. The top part of the shroud contains an opening for the sanitizer’s temperature controls.
  • Material used: BMC –glass-filled wet polyester
  • Requirements: Heat resistance with a high-quality matte finish. Dielectric properties insulate the shroud from its electric heater and controls. The material chosen allows this part to be molded in a variety of colors and textures to meet customer needs.


Off-road equipment used in the agriculture industry, such as farm tractors and combines, are exposed to extreme heat, dust and vibration daily. Parts used in this application must have excellent mechanical stability and heat resistance.

Relay module housing

  • Application: This part is used to hold high-voltage electrical relays and fuses on farm tractors.
  • Material used: BMC – high glass-filled wet polyester.
  • Requirements: Dielectric (insulating) properties, heat resistance, mechanical stability and creep resistance, due to the number of components that need to be attached to this housing.


Parts used in aerospace applications need to be lightweight but strong. In many cases, thermoset resins are being used to replace heavier metals used to make components. In some cases, parts need to be paintable to match the color scheme of the instrument panels where they’re being used.


Front and rear circuit breaker panels

  • Application: These panels are in the cockpits of aircraft, where the crew can easily monitor and reset circuit breakers. The front panel contains the breakers, while the back panel sits behind it and protects it against wiring and other equipment.
  • Material used: BMC – glass-filled wet polyester.
  • Requirements: Light weight. Dull surface finish, so the panels don’t reflect light into the eyes of the flight crew.

Aerospace actuators

  • Application: Coil forms, cases and bobbins used in hydraulics to control ailerons and other flight surfaces on aircraft.
  • Material used: Diallyl phthalate and epoxy.
  • Requirements: Light weight and high strength. Temperature and moisture resistance. Aircraft are subject to low temperatures when flying at high altitudes.

Lab Equipment 

Parts used in lab applications need to have a high-quality finish and excellent chemical resistance. Depending upon the application, they may also need to exhibit excellent heat resistance.


Alcohol torch body

  • Application: This type of torch is used in dental labs to melt the wax that is used to make dentures.
  • Material used: Heat-resistant phenolic.
  • Requirements: This part must be heat resistant and flame retardant because of the flame of the torch. It must also be corrosion resistant because alcohol can affect the surface finish and integrity of plastics. This part also requires dimensional stability, because multiple holes must be drilled and tapped into it to hold the wick, the torch itself and its nozzle holder. The parts need to align precisely for proper assembly.

Contact CI-Dell today to discuss your specialty molding needs.

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