PEEK Injection Molds: Why Grade Selection Decides the Outcome

PEEK is often specified as a single word, as if it described one material. In practice the grade you choose changes stiffness, wear behaviour, flow in thin walls and price by a factor of several — and the mold has to be designed around that choice.

What actually differs between grades

• Unfilled versus reinforced — 30 % carbon-fibre grades such as 450CA30 are markedly stiffer and more wear resistant, but they are abrasive on the tool and shrink far less along the fibre direction.
• Molecular weight and flow — a high-flow grade fills a thin, complex geometry that a general-purpose grade simply will not fill, at some cost in toughness.
• Regulatory status — medical and aerospace applications constrain the choice long before price enters the discussion.

Why we evaluate both sides

International grades from Victrex, Solvay and Evonik are the reference points, and we keep representative grades on hand. Domestic industrial PEEK is now mature and costs roughly half as much. For many industrial parts it performs perfectly well.

The honest answer is that the cheaper grade is sometimes right and sometimes not, and the difference shows up in specific strength, creep under sustained load, or dimensional stability across a thermal cycle — not in the datasheet headline figures. We tell you which side of that line your part falls on, before the mold is cut.

The mold consequences

Grade choice drives gate size, shrinkage compensation, steel wear allowance and venting. Change the grade after the tool is built and some of those become expensive. This is why material analysis comes first in our process, not last.