Archive: Oct 2021

Thermoset Plastics vs. PEEK

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There are two main categories of plastics: thermosets and thermoplastics. Due to a change in molecular structure, thermoset materials keep their form and remain solid under heat once cured. Thermoplastics can be repeatedly reground, reheated and remolded. In addition to the difference in their reactions to the application of heat, these material groups also demonstrate other distinct characteristics that make them suitable for different use cases.
Below, we highlight PEEK, a commonly used engineered thermoplastic material. We outline what properties it exhibits, what it is used for, and how it compares to thermoset plastics.

What Is PEEK?

Polyetheretherketone (PEEK) is a semi-crystalline thermoplastic with excellent mechanical and chemical properties. In addition to resistance to chemicals, radiation, water absorption, and wear, it offers thermal stability in temperatures up to 480° F. It can also face hot water or steam without compromising its physical properties. These qualities, combined with its strength and stiffness, make it a suitable material for parts and products used in demanding environments. It is commonly used to make components for industries such as aerospace, automotive, medical, and semiconductor.

Advantages of Thermoset Plastics Over PEEK

As a high-performance thermoplastic material, PEEK finds use in many industrial applications. However, thermoset plastics demonstrate a variety of characteristics that can make them a better option for certain manufacturing projects. For example, since thermoset plastics undergo an irreversible chemical change when cured, they typically offer better thermal stability than any thermoplastic material, including PEEK.
Other key advantages thermosets have over PEEK include:

  • Greater design freedom. Thermosets can be molded into nearly any geometry, which provides designers and engineers with greater freedom when creating a design.
  • Better physical and chemical properties. In addition to thermal stability, thermosets offer superior strength, stiffness, dimensional stability, and durability when compared to thermoplastics. As a result, components made from them can withstand harsher operating and environmental conditions. They also exhibit other advantageous physical properties, such as low water absorption, low smoke and toxicity, and low specific gravity.
  • Lower cost. In addition to being generally less expensive than alternative materials, thermoset plastics can also save money during the manufacturing process. A single mold can be used to create complex parts with many options in using inserts in a product design. Inserts can be molded-in during the molding cycle or tapped/press-fit into the part after molding.

Working With MCM Composites’ Thermoset Plastics

Need a manufacturing partner with experience working with thermoset plastics? Turn to the experts at MCM Composites. We can help you develop the right molding solution for your PEEK application, whether it involves environmental temperature requirements up to and exceeding 500°F or multi-piece to single-piece conversions.
For more information about our thermoset molding capabilities and how they can benefit your manufacturing processes, contact us today. To discuss your thermoset molding needs with one of our team members, request a quote.

Thermoset Plastics vs. Ultem Plastics

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Thermoset plastics are a popular type of molding compound used in many engineered plastic applications. Once thermoset plastics are heated and start to set, the curing process chemically alters the material so it can’t be reground or reused. Thermoset materials are cost-effective and durable, making them an ideal choice for many manufacturing projects. Conversely, thermoplastics can be returned to a ground state and recast or reused multiple times without altering the chemical structure of the material. This blog will discuss the differences between thermoset plastics and Ultem®, a specific type of thermoplastic.

What is Ultem?

Of all the different thermoplastic materials used for manufacturing goods, Ultem is one of the most advantageous for high-heat applications. This polyetherimide compound features a high melting point for a thermoplastic, which means it can be used to produce parts that stay rigid and reliable at temperatures up to 340°F. The high melting has led some engineers to choose Ultem in situations where a thermoset plastic might traditionally be used. Ultem also features good dielectric properties, high strength, rigidity, and resistance to most chemical damage.

Some of the most common applications for Ultem include:

  • Circuit boards
  • Electrical insulators
  • Electronic insulators
  • Eyeglasses
  • Food prep equipment
  • Jet engine components
  • Manifolds
  • Medical components
  • Microwaves
  • Sterilization equipment

Thermoset Plastic Advantages Over Ultem

Despite the benefits offered by Ultem and other thermoplastics, thermoset plastics remain advantageous in many applications. Manufacturing with thermoset materials presents many key advantages that are valuable during manufacturing and during the lifecycle of the product. The advantages of thermosets over Ultem include:


Thermoset compounds are less expensive than thermoplastics, which reduces overall production costs. Lower material costs also allow for a greater margin of experimentation and modification without exceeding a set budget.


Thermoset compounds can be molded into products with any geometry. No matter how complex the product design is, manufacturers can use thermosets to create solid, tough pieces with a high degree of structural integrity. This is ideal for parts that face extreme end-use environments and need to meet tight tolerances for complex configurations.

Physical Properties

Thermoset materials offer a wide variety of beneficial characteristics. After the curing process, thermoset parts have a high degree of rigidity and can withstand impact damage. The products are also strong and resistant to heat damage. Because of the excellent manufacturability thermoset plastics offer, they can be molded to extremely tight tolerances. This is ideal for electronic product components or complex mechanical assemblies with little room for error or misalignment.


Thermoset plastics feature an excellent strength-to-weight ratio. That means the products offer a high degree of strength while still being light and easy to handle. They dampen sound, resist creep, and have a low coefficient of friction that mitigates damage from abrasion. Thermosets are ideal for parts that need to retain quality and structural integrity long-term.


Thermoset products are stable and resistant to impact damage, UV radiation, fluid exposure, and heat. Some thermosets can retain their stability in environments that reach sustained temperatures of 500°F.

Thermoset Plastics and MCM Composites

At MCM Composites, we offer an extensive array of manufacturing services designed to create high-quality thermoset products. We offer thermoset injection molding and thermoset compression molding services for customers across industries. Contact us today or request a quote to see how our thermoset plastic molding capabilities can support your design.