Common types of high temperature plastics include polyimides (PI), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), liquid crystal polymers (LCP), Polyethersulfone (PES), Polyphenylsulfone (PPSU), Polyether Imide (PEI), Polysulfone (PSU), PolyEtherKetone-EtherKetoneKetone (PEKEKK), Polyetherketone (PEK), Polytetrafluoroethylene(PTFE), Perfluoroalkoxy Alkanes (PFA), Polyvinylidene Fluoride(PVDF), polysulfones.Key application areas are in aerospace, automotive, oil & gas, electronics and medical sectors.

High Temperature Injection Molding is an injection molding technology characterized by the injection filling and cooling process when the mold temperature is usually higher than 150°C and the molding temperature is usually higher than 300°C.

Different from conventional injection molding, high-temperature injection molding uses high-temperature molds to reduce the viscosity of the molten plastic and enhance the fluidity of the material in the mold cavity. It can fill the mold cavity more fully and evenly, reduce flow lines and internal stress, and improve the appearance of molded parts. . These advantages make it particularly suitable for materials such as engineering plastics that are difficult to mold at conventional temperatures. For example, PEEK, PPS, PFA, PEI, PES, etc.

However, high-temperature injection molding also places higher requirements on mold materials and cooling systems. Care must be taken to prevent long-term high temperature damage to the mold.

High temperature plastics also called high-performance plastics, refer to a class of high performance thermoplastic polymers that can withstand and operate at elevated temperatures, typically in the range of 150°C to over 260°C. Some key characteristics of high temperature plastics:

• High heat resistance and thermal stability at continuous-use temperatures above 150°C without significant thermal degradation or dimensional changes. This high heat distortion temperature allows them to replace metals in many applications.
• Good mechanical properties such as strength, stiffness, creep resistance and toughness at both room and elevated temperatures. This allows them to maintain mechanical performance when exposed to heat.
• High chemical resistance against acids, bases, fuels, oils and solvents. This provides durability in harsh chemical environments.
• Flame retardance and self-extinguishing properties for safety in high heat applications.

Here are some of the main challenges associated with high temperature injection molding:

• Mold materials – The mold must withstand prolonged exposure to high temperatures without losing dimensional stability or wearing prematurely. This requires mold materials like beryllium-copper alloys or specialized tool steels.
• Thermal expansion – The significant expansion and contraction of mold components with temperature cycling can lead to issues with precision, part quality, and mold life. Precise allowance must be made for thermal expansion.
• Cooling system – An efficient cooling system is critical to bring down cycle times. This is challenging due to the hot mold surfaces. Conformal cooling channels close to the mold surfaces are often required.
• Process control – Tight control over temperatures, pressures, timing, and velocities is crucial to achieve a balanced fill and optimum part quality. This requires precise process monitoring and control.
• Part ejection – Hot parts tend to stick in the mold or deform during ejection. The right ejection force, timing, and temperature control is important.
• Resin drying – Many high temperature polymers are hygroscopic. Adequate resin drying is essential to avoid splay and inconsistent properties.
• Warpage and stresses – Residual stresses due to uneven cooling and shrinkage can induce significant warpage in parts. This may require modifications in part and mold design.
• Cost – The mold materials, cooling requirements, and process control systems required make high temperature injection molding an expensive process.

As a high temperature molding company with over 15 years of experience, we have extensive experience in this type of high performance plastics molding. Here are some of the key points we summarized. Careful selection of mold materials, mold deign, mold making, process optimization, tolerance control and mold flow analysis are key enablers for high temperature injection molding.

Here are some key factors for successful high temperature injection molding:

• Mold materials – Use hardened tool steels or beryllium-copper alloys to withstand prolonged exposure to temperatures above 150°C.
• Mold cooling system – Effective conformal cooling channels close to the mold surfaces are essential for rapid cycling.
• Temperature controls – Precise monitoring and control of nozzle, barrel, mold temperatures to maintain process consistency.
• Materialdrying – Many high temp polymers are hygroscopic. Moisture content must be kept very low through proper drying.
• Dimensional tolerance – Account for and minimize thermal expansion effects to maintain tight tolerances.
• Part and mold design – Optimize wall thickness and geometry to ensure adequate stiffness and avoid warpage.
• Demolding – Controlled ejection force and timing required to avoid part distortion while hot.
• Process monitoring – Critical process parameters need real-time monitoring to identify any deviations.

While high-temperature molding can achieve higher quality parts, the costs involved tend to be higher than conventional injection molding, both in terms of material costs and mold and injection molding costs. But compared with the cost of other materials, it still has advantages. High-temperature plastic parts have a long service life, are resistant to high temperatures and corrosion, are lightweight and durable. Therefore, in the long run, the cost is lower than products made of iron, aluminum and other materials.