Exablend® POK GF50 F4 — High-Stiffness 50% GF Polyketone for Stable Structural Parts

Exablend® POK GF50 F4 — high-stiffness polyketone with 50% GF for stable structural parts

Exablend® POK GF50 F4 is a highly filled polyketone-based compound reinforced with 50% glass fiber. The grade is intended for molded parts that require high stiffness, low shrinkage, geometric stability and reliability in contact with technical media.

This material belongs to the group of rigid structural POK compounds, but it should not be described through its glass fiber content alone. The strength of Exablend® POK GF50 F4 lies in the combination of reinforcement, the polyketone matrix and controlled molding behavior. The material is of interest for parts where stiffness must work together with chemical resistance, wear resistance, low moisture sensitivity and dimensional repeatability in serial production.

Engineering rationale of the grade

POK GF50 F4 is worth considering for parts where a simple increase in strength no longer solves the problem. In structural housings, support elements, precision parts or under-hood components it is important not only to withstand the load, but also to maintain fit dimensions, retain stiffness in a warm environment and avoid uncontrolled geometry changes after molding.

This is where the 50% glass fiber has practical significance: it increases the modulus, reduces shrinkage, limits deformation under load and allows the polymer part to be treated as a structural element rather than a simple substitute for a standard plastic. The polyketone matrix adds resistance to chemical and fuel-and-oil media, which is particularly important for automotive, industrial and precision technical assemblies.

Where the material performs best

Exablend® POK GF50 F4 makes sense where a rigid molded part with low shrinkage, a good thermal margin and stable performance is required in a more demanding environment than dry office or household use. It is a material for parts that must remain geometrically accurate after molding, assembly, heating, contact with technical fluids or cyclic loading.

• structural automotive parts;
• under-hood components;
• rigid technical housings;
• electronic and electrical housing elements;
• precision gears;
• support elements of mechanisms;
• parts where metal replacement is being considered;
• assemblies operating near fuel, oils or technical fluids.

How this grade differs in engineering logic

While POK GF30 is more often chosen as a balanced reinforced material, GF50 F4 has a different emphasis — higher stiffness, lower shrinkage and a stronger focus on structural stability. It is a grade for cases where part deformation, deflection, fit instability or gap changes may be more critical than maximum impact strength.

At the same time, GF50 F4 should not be perceived as a “plastic metal” without limitations. The high glass fiber content creates anisotropy, flow-direction-dependent properties, sensitivity to weld lines and higher demands on mold design. The material delivers the best results when it is selected together with the part geometry, the gating scheme and the actual operating conditions.

Key advantages of Exablend® POK GF50 F4

• 50% glass fiber for high stiffness and shape stability;
• low linear shrinkage: 0.1–0.3% in the flow direction;
• flexural modulus of 11 800 MPa;
• tensile strength of 165 MPa;
• flexural strength of 214 MPa;
• HDT of 215°C at 0.45 MPa load;
• resistance to chemical and fuel-and-oil media;
• good suitability for precision molded parts with demanding geometry requirements;
• potential for metal replacement in moderately loaded parts.

Technical specifications

The main physical-mechanical and thermal characteristics are given in the table below. For this grade it is important to assess not only strength but the whole set of parameters: the level of reinforcement, shrinkage, flexural modulus, HDT, impact behavior and geometric stability after molding.

Processing recommendations

Exablend® POK GF50 F4 is intended for injection molding. Due to the high glass fiber content, mold filling, fiber orientation, injection pressure, tooling condition and cooling uniformity must be controlled. For such materials the actual part quality is often determined not only by the pellet properties, but also by how correctly the mold, the gating and the processing regime are designed.

The material is supplied pre-dried, but requires moisture control after the packaging is opened. For stable molding, drying before processing is recommended, especially if the bag has been opened or the material has been exposed to air.

Design considerations

For parts made of POK GF50 F4, the flow direction, glass fiber orientation, weld line locations, the difference in shrinkage along and across the flow, fillet radii, local stress concentrations and the potentially abrasive effect of the material on tooling must all be taken into account.

This grade is well suited to applications that require a rigid, stable and chemically resistant part, but it should be tested on the actual geometry. It is in the finished part that the effects of reinforcement, fiber orientation, cooling regime and assembly design become visible.