PEEK in perfection: injection molding at the molecular level for sound technology
In audio equipment, everything revolves around the pure transfer of vibration. What you hear depends on what you don’t see - the parts that transmit, dampen, or guide the sound. For a Dutch start-up, ENBI developed an injection molding solution for a high-end audio component that performs this task with exceptional precision. The key lay in one material: PEEK – polyetheretherketone.
PEEK is a high-performance polymer with an exceptional combination of stiffness, heat resistance, and dimensional stability. These properties are essential in an environment where vibrations must be transferred accurately, without distortion or resonance. Yet those same qualities make PEEK one of the most challenging materials to process.
Crystallization as the core of the solution
The audio component needed to be not only strong and dimensionally stable but also exhibit the right degree of molecular crystallization. Only then could the internal structure deliver optimal stiffness and controlled resonance.
PEEK melts at around 340°C and is processed at over 350°C. However, the desired crystallization occurs during cooling, when the material in the mold reaches approximately 250 to 285°C.
This means the mold temperature must remain unusually high - around 170 to 180°C - to allow the material time to align and form the ideal crystalline structure. Achieving that balance between flow, cooling, and cycle time is critical: cool too fast and internal stress or fracture occurs; too slow and the cycle time becomes inefficient.
The challenge was to maintain a consistent temperature across the entire flow path so that the molecular structure could form uniformly. Only with precise thermal control could the crystallization rate be accurately managed - essential for product quality and structural stability.
Precision in process and mold temperature
To achieve this balance, ENBI designed a four-cavity mold with temperature control at its core. A sophisticated heat transfer system precisely regulated the temperature during every cycle.
Only with that level of control did crystallization remain consistent throughout the entire flow path - a prerequisite for stable product properties.
This process control was key to achieving the required combination of stiffness, hardness, and vibration transmission. The component functions as an acoustic carrier that transfers sound waves without loss or distortion - a microscopically precise task performed by a polymer shaped under extreme processing conditions.
Where material and function meet
The choice for PEEK was no coincidence. The material remains stable at operating temperatures up to 300°C and retains its mechanical properties even under long-term load. This combination of thermal stability and vibration control makes it ideal for applications in the audio industry, where precision is literally audible.
By combining deep knowledge of material behavior with advanced process engineering, ENBI found the perfect balance between design, functionality, and manufacturability. The result is a highly stable, high-performance component that plays a crucial - yet unseen - role in sound quality.
Unseen, yet essential
This development demonstrates how far the boundaries of injection molding can be pushed when material science, temperature control, and precision manufacturing come together - a solution engineered at the molecular level.
Unseen, yet essential!
