RENJIE® Injection Molded PEEK: Properties, Processing Parameters and Applications

PEEK (polyetheretherketone) is a high-performance thermoplastic engineering plastic with an excellent overall property balance, which makes it particularly well suited to precision injection moulding. It is, however, an unforgiving material to process: high melting point and high melt viscosity mean the parameters must be set deliberately, not inherited from a PA or POM job.

This guide covers the property profile that justifies PEEK, the processing window that makes it work, and where it is actually used.

Properties of Injection Molded PEEK

High temperature resistance

Continuous operating temperature reaches 260 °C, with short-term resistance to 300 °C or higher. The heat distortion temperature under 1.8 MPa load exceeds 300 °C, so the material holds its shape in service temperatures that would soften most engineering plastics.

Excellent mechanical properties

High strength, high rigidity and fatigue resistance, with good mechanical stability even at elevated temperature — the combination that allows metal parts to be replaced without losing load capability.

Chemical corrosion resistance

Excellent resistance to acids, alkalis, oils, organic solvents and most chemicals. The material is corroded only in strong oxidising media such as concentrated sulphuric acid — a critical distinction when specifying seals and pump internals.

Low friction and wear resistance

Excellent self-lubricating properties and a low coefficient of friction allow long-term operation without lubrication, removing grease from the design and the maintenance schedule.

Electrical insulation

High dielectric strength with low dielectric constant and loss factor, maintaining stable electrical properties even at high frequencies and high temperatures — suited to connectors and test fixtures rather than only structural parts.

Dimensional stability

Extremely low water absorption (<0.1%) gives high dimensional accuracy after moulding and minimal shift with humidity, so a part moulded to tolerance stays within tolerance in a humid plant.

Injection Molding Processing Technology

Processing injection moulded PEEK requires special control because of its high melting point and high viscosity. The window below is the working baseline.

1. Raw material preparation

Dry the resin at 150–160 °C for 3–4 hours before injection moulding. This removes trace moisture and prevents bubbles and silver streaks in the moulded part.

2. Injection temperature control

Barrel temperature: 360–400 °C, adjusted according to part thickness and flowability requirements. Nozzle temperature: 370–400 °C. Mould temperature: 150–200 °C, which ensures sufficient crystallisation and reduces internal stress.

3. Injection parameters

Injection speed: medium to high, to ensure complete mould filling. Holding pressure: appropriately high, to reduce shrinkage and warpage. Screw speed: 30–60 rpm, to avoid shear overheating.

4. Post-treatment

Annealing at 150–200 °C for 1–2 hours eliminates internal stress and improves dimensional stability. Skipping it is the usual reason a PEEK part measures correctly on the bench and drifts after annealing or in service.

Reading the process window

Applications of Injection Molded PEEK

Frequently Asked Questions

What barrel temperature should be used for PEEK? 360–400 °C, adjusted for part thickness and flowability. Nozzle temperature runs slightly higher, at 370–400 °C.

What mould temperature does PEEK need? 150–200 °C. A hot mould ensures sufficient crystallisation and reduces internal stress; a cold mould produces brittle, dimensionally unstable parts.

Does PEEK need drying before moulding? Yes. Dry at 150–160 °C for 3–4 hours to remove trace moisture and avoid bubbles and silver streaks.

Is annealing necessary? Annealing at 150–200 °C for 1–2 hours eliminates internal stress and improves dimensional stability. It is strongly recommended for precision parts.

What is PEEK's maximum service temperature? Continuous operating temperature up to 260 °C, short-term up to 300 °C or higher, with HDT/A at 1.8 MPa exceeding 300 °C.

What chemicals attack PEEK? Strong oxidising media such as concentrated sulphuric acid. PEEK resists acids, alkalis, oils, organic solvents and most other chemicals.

Moulding PEEK with RENJIE®

• Consistent granule quality — moisture-controlled supply, so drying behaves predictably.
• Grade selection support — unfilled, carbon-filled, glass-filled and ESD grades matched to the part, not the catalogue.
• Process guidance — the parameter window above, plus troubleshooting support for first-article runs.

Send your part drawing, service temperature and chemical exposure to receive a grade recommendation and processing sheet.