Polyoxymethylene (POM) or acetal is another engineering thermoplastic in a lower price bracket than ultra-premium materials like PEEK. It provides good stiffness and low friction, with a relatively high CST. Molded POM can be made into various engineering parts like gears and fasteners, as well as automotive and electronics parts.

EVCO Plastics has many years or experience with multi-shot and two-shot plastic injection molding, and designing and building high quality multi-shot and two-shot molds, for a wide range of applications, including:

We specialize in multi-shot injection molding, as well as two-shot plastic injection molding. It is an efficient and cost-effective method for molding custom plastic parts with two or more plastic resins or colors in one operation. We have extensive experience in designing and building high-quality molds for multi-shot and two-shot injection molded plastics for a wide range of applications.

So which are the best heat-resistant thermoplastics for injection molding? This article discusses some of the most popular thermally resistant injection molding materials, noting their respective advantages and applications, as well as discussing the complexities of using such materials during the injection molding process.

Engineers sometimes need temperature-resistant moldings that do not need to be of aerospace-grade quality. In these cases, they can choose from more affordable temperature-resistant polymers with good engineering properties. (For the lowest possible budgets, engineers might select a commodity polymer like ABS, which has a reasonable CST of 90 °C but which is also sold in various “high heat” ABS formulations resisting up to 110 °C.)

Another molding consideration with high-temperature plastics is unwanted freezing off of the nozzle or mold gates. If temperatures are not quite high enough, gates or the machine nozzle can freeze off before the mold cavity is completely filled. Larger gates may mitigate this issue if it persists.

For an ultra high-temp plastic like PEEK, the injection molding machine barrel will reach temperatures above 400 °C, with the molds around 160 °C. These high temperatures can pose certain issues, such as residue getting stuck in the barrel feeder areas. High-temp materials like PEEK often necessitate purging of the machine before use of a subsequent molding material.

Polyether ether ketone (PEEK) is a high-performance polymer used for engineering purposes. With a melting temperature of 343 °C, it is as robust and strong as it is difficult to process. Its extremely high CST makes it suitable for applications in demanding industries like aerospace. Example PEEK parts include bearings, pumps, and compressor plate valves.

Engineers will select a thermoplastic based on the requirements of the molded part. Some moldings need to be impact-resistant, some need to be food-safe, while others need to be flexible. Another property that engineers and product designers often require is heat resistance. Heat-resistant molded parts can be used in a range of situations, such as near engines, within powerful electronic parts, and in extreme outdoor environments.

Because the injection molding machine must melt down pellets of the chosen thermoplastics, high-temperature materials are necessarily more difficult to process. However, with the right setup, it is still possible to achieve high-quality moldings using these engineering materials.

The most temperature-resistant injection molding plastics come at a high cost but exhibit excellent thermal performance, both in terms of their continuous service temperature (CST) — how much heat they can withstand over long periods of time — and their resistance to even higher temperatures in short bursts.

Polycarbonate (PC) is often used for its high-quality appearance — especially for transparent parts — and good impact resistance, but the thermoplastic also offers good heat resistance. PC can be molded for uses in electronics, automotive, and aerospace. It is also used for optical and lighting components like headlamp lenses.

3ERP has many years of experience making prototypes and production parts via injection molding, and we can mold parts in the above materials and many more besides. Request a free quote for your next batch of high-temperature plastic parts.

Injection molding can process a wide range of materials. In addition to metals and thermosets, injection molding is suited to a large number of thermoplastic polymers, from commodity polymers like ABS to high-performance materials like PEEK.

Specialize in CNC machining, 3D printing, urethane casting, rapid tooling, injection molding, metal casting, sheet metal and extrusion

Polyetherimide (PEI), often known by the brand name Ultem, is a high-performance polymer often used as a slightly more affordable alternative to PEEK. As well as performing well in high temperatures, it offers good strength, ductility, and chemical resistance. Applications of PEI include medical components, throttle bodies, and thermostat housings.

In multi-shot and two-shot custom plastic injection molding, plastic polymers from two or more injection units are applied through independent nozzles on one plastic injection molding machine to produce custom plastic parts such as soft-grip handle inserts, multi-colored parts, dashboard or instrumentation, or parts with molded seals, flexible hinges, or movable components.

Nylon 66 is one of the more heat-resistant polyamides (PA) that is widely used in injection molding. With good mechanical strength and rigidity, nylon 66 has applications in the automotive industry for under-the-hood components like air intake manifolds. Glass-filled PA66 has a slightly higher CST, while PA46 is another good choice for high-temp applications.

Polyphenylene sulfide (PPS) is another high-performance polymer with engineering applications. As well as having a high CST, it exhibits excellent UV and chemical resistance, making it suitable for outdoor use. PPS parts include gaskets, seals, and electrical insulation. Polyphenylsulfone (PPSU) is slightly weaker and less thermally resistant, but exhibits greater hardness.