Heat-Resistant Plastics: Top Choices for Injection Molding

Injection molding boasts a broad material compatibility, encompassing not only metals and thermosets but also an extensive array of thermoplastic polymers, ranging from common ABS to high-performance PEEK.

Selecting Thermoplastics for Specific Requirements

Engineers meticulously choose thermoplastics based on the precise needs of the molded component. Some applications necessitate impact resistance, while others mandate food safety compliance or flexibility. Furthermore, heat resistance emerges as a critical property sought by engineers and product designers, enabling applications in proximity to engines, high-powered electronics, and harsh outdoor environments.

Identifying Optimal Heat-Resistant Thermoplastics

Delving into the realm of heat-resistant materials suitable for injection molding, this article evaluates prominent thermoplastic options renowned for their thermal resilience. Highlighting distinctive advantages and application scopes, the discussion elucidates the intricacies inherent in employing these materials within the injection molding process.

Evaluating Premium Temperature-Resistant Plastics

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Temperature-resistant injection molding plastics, while commanding a premium price, demonstrate outstanding thermal characteristics, encompassing both continuous service temperature (CST) — indicative of sustained heat endurance — and resistance to elevated temperatures during brief exposure.

1. PEEK (Polyether Ether Ketone)

  • Maximum CST: 260 °C

PEEK stands as a high-performance polymer renowned for its engineering applications. Despite its formidable melting point of 343 °C, processing this material poses challenges due to its robustness. Its exceptional CST renders it ideal for demanding sectors such as aerospace, where components like bearings, pumps, and compressor plate valves exemplify its utility.

2. PPS and PPSU (Polyphenylene Sulfide and Polyphenylsulfone)

  • Maximum CST: 220 °C and 210 °C

PPS emerges as another high-performance polymer tailored for engineering applications. Beyond its elevated CST, it boasts commendable UV and chemical resistance, rendering it suitable for outdoor usage. Applications span from gaskets and seals to electrical insulation. Conversely, PPSU, while slightly less thermally resistant, compensates with enhanced hardness.

3. PEI (Polyetherimide)

  • Maximum CST: 170 °C

Commonly recognized under the brand name Ultem, PEI serves as a high-performance polymer offering a marginally more cost-effective alternative to PEEK. Alongside its proficiency in high-temperature environments, PEI showcases commendable strength, ductility, and chemical resistance. Medical components, throttle bodies, and thermostat housings represent just a fraction of its diverse applications.

Cost-Effective Temperature-Resistant Plastics

In scenarios where aerospace-grade quality is not imperative, engineers seek affordable temperature-resistant polymers boasting commendable engineering attributes. For budget-conscious projects, even commodity polymers like ABS, with a reasonable CST of 90 °C, offer viable options, especially in their “high heat” formulations resisting temperatures up to 110 °C.

1. PC (Polycarbonate)

  • Maximum CST: 140 °C

Polycarbonate, prized for its superior aesthetic appeal and impact resistance, also exhibits noteworthy heat resistance. Widely utilized in electronics, automotive, and aerospace sectors, PC finds applications in transparent parts as well as optical and lighting components such as headlamp lenses.

2. PA 66 (Nylon 66)

  • Maximum CST: 140 °C

Nylon 66, a heat-resistant polyamide, enjoys extensive adoption in injection molding owing to its robust mechanical strength and rigidity. Particularly prevalent in the automotive industry, it serves under-the-hood components like air intake manifolds. Glass-filled variants offer enhanced CST, while PA46 presents another compelling option for high-temperature applications.

3. POM (Polyoxymethylene)

  • Maximum CST: 105 °C

Polyoxymethylene, commonly known as acetal or POM, stands as an engineering thermoplastic offering competitive pricing compared to ultra-premium materials like PEEK. Noteworthy for its stiffness and low friction, POM finds utility in diverse engineering applications including gears, fasteners, and automotive and electronics components.

Critical Factors in Injection Molding

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In injection molding processes involving high-temperature materials, certain challenges arise due to the necessity of melting thermoplastic pellets. Despite the inherent complexities, optimal setups can still yield superior moldings using these advanced engineering polymers.

Temperature Management

For ultra high-temperature plastics such as PEEK, meticulous temperature control is imperative. Injection molding machine barrels must surpass 400 °C, while molds typically maintain temperatures around 160 °C. However, such elevated temperatures can lead to issues like residue accumulation in barrel feeder areas. Consequently, thorough purging of the machine becomes necessary before transitioning to a different molding material.

Preventing Freezing Off

Another critical consideration involves preventing the undesired freezing off of nozzles or mold gates. Inadequate temperatures may result in premature solidification, causing gates or the machine nozzle to freeze off before the mold cavity is fully filled. To address this challenge, utilizing larger gates can help mitigate freezing-off concerns and ensure consistent molding processes.

Injection Molding High-Temperature Plastics with BOYI

BOYI boasts extensive experience in producing prototypes and manufacturing parts through injection molding. Our expertise extends to molding parts using various high-temperature plastics, including those mentioned above and beyond. Reach out today for a complimentary quote on your upcoming high-temperature plastic parts production.

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