PSU CF10: Properties, Machining, and Applications Guide

Polysulfone (PSU) is a high-performance thermoplastic known for its exceptional thermal stability, mechanical strength, and hydrolytic resistance. The CF10 grade represents a specialized variant where PSU is reinforced with 10% carbon fiber, significantly enhancing its stiffness, dimensional stability, and creep resistance while maintaining the inherent benefits of the base polymer. This guide provides a comprehensive technical overview of PSU CF10, covering its chemical composition, mechanical and physical properties, key characteristics, typical applications, and machining considerations. Engineers and procurement specialists will find detailed insights to determine if this material is suitable for demanding precision components. For specialized projects requiring tight tolerances, understanding how to machine this material is critical, much like the precision required for CNC camera parts.

Chemical Composition and Structure of PSU CF10

Base Polymer: Polysulfone (PSU)

Polysulfone is an amorphous thermoplastic characterized by a backbone of aryl groups linked by sulfone (-SO2-) and ether (-O-) groups. The sulfone group imparts high oxidative and thermal stability, while the ether linkage provides chain flexibility. The repeating unit is typically derived from bisphenol A and 4,4′-dichlorodiphenyl sulfone. This molecular structure results in a material that maintains its mechanical properties over a wide temperature range, from -100°C to +150°C, and exhibits excellent resistance to hydrolysis and mineral acids.

Carbon Fiber Reinforcement (10%)

The “CF10” designation indicates the inclusion of 10% by weight carbon fiber. These fibers are typically short, chopped strands (approximately 6 mm in length) that are uniformly dispersed within the PSU matrix during compounding. The carbon fibers act as a reinforcing phase, bearing a significant portion of the applied load. This addition increases the tensile modulus from around 2.5 GPa for unfilled PSU to approximately 6-8 GPa for the CF10 grade. The fibers also reduce the coefficient of thermal expansion (CTE) and improve creep resistance, making the material more dimensionally stable under load and temperature variations.

Additives and Fillers

In addition to the carbon fiber reinforcement, PSU CF10 formulations may include small amounts of stabilizers, processing aids, and lubricants. Thermal stabilizers, such as phosphite antioxidants, are added to prevent degradation during high-temperature processing. Internal lubricants, often based on polytetrafluoroethylene (PTFE) or silicone, can be incorporated to improve mold release and reduce friction during machining. These additives are typically present at less than 1% by weight and do not significantly alter the bulk properties.

Mechanical Properties of PSU CF10

Tensile and Flexural Strength

The addition of carbon fibers dramatically improves the tensile and flexural strength of PSU. Unfilled PSU has a tensile strength of approximately 70-80 MPa. PSU CF10 exhibits a tensile strength of 110-130 MPa, depending on the specific grade and processing conditions. Flexural strength follows a similar trend, increasing from about 100 MPa for unfilled PSU to 150-170 MPa for the CF10 variant. This makes the material suitable for structural applications where load-bearing capacity is required.

Modulus and Stiffness

The stiffness, measured by the tensile modulus, is the most significantly enhanced property. Unfilled PSU has a tensile modulus of approximately 2.5 GPa. PSU CF10 achieves a modulus of 6-8 GPa, representing a 140-220% increase. This high stiffness reduces deflection under load, making PSU CF10 ideal for components that must maintain precise dimensions, such as jigs, fixtures, and structural brackets. The flexural modulus is similarly elevated, typically ranging from 5 to 7 GPa.

Impact Resistance and Creep

While carbon fiber reinforcement improves strength and stiffness, it typically reduces impact resistance. The notched Izod impact strength of unfilled PSU is around 70-80 J/m. For PSU CF10, this value drops to 20-40 J/m, indicating a more brittle material. Designers must account for this by avoiding sharp notches and stress concentrators. Creep resistance, however, is substantially improved. At 100°C and 10 MPa stress, unfilled PSU may exhibit 1% creep strain after 1000 hours, while PSU CF10 shows less than 0.3% under the same conditions. This makes PSU CF10 superior for long-term load-bearing applications.

Mechanical Properties Comparison Table

Note: Values are typical and may vary by specific grade and manufacturer.

物理与热学性能

Density and Water Absorption

The density of PSU CF10 is slightly higher than unfilled PSU due to the denser carbon fiber. Unfilled PSU has a density of 1.24 g/cm³, while PSU CF10 has a density of approximately 1.30-1.34 g/cm³. Water absorption is low, typically 0.3% after 24 hours immersion in water at 23°C, and about 0.7% at saturation. This low moisture absorption contributes to excellent dimensional stability, even in humid environments.

Thermal Stability and Glass Transition Temperature

PSU CF10 maintains the high glass transition temperature (Tg) of the base polymer, typically around 185-190°C. The material can be used continuously at temperatures up to 150°C, with short-term excursions to 170°C. The heat deflection temperature (HDT) at 1.82 MPa is approximately 175°C, compared to 170°C for unfilled PSU. The carbon fiber reinforcement does not significantly alter the Tg but improves the material’s ability to maintain stiffness at elevated temperatures.

Coefficient of Thermal Expansion (CTE)

One of the key advantages of PSU CF10 is its reduced CTE. Unfilled PSU has a CTE of about 56 x 10⁻⁶ /°C (linear). PSU CF10 exhibits a CTE of 20-30 x 10⁻⁶ /°C, depending on the fiber orientation. This reduction is critical for applications where the material must maintain dimensional accuracy across temperature changes, such as in precision fixtures or optical components. The CTE is anisotropic; it is lower in the direction of fiber orientation.

Physical Properties Comparison Table

Key Characteristics and Advantages

Hydrolytic Stability and Chemical Resistance

PSU CF10 retains the excellent hydrolytic stability of the base polymer. It can withstand repeated steam sterilization cycles (autoclaving at 121°C) without significant degradation. This makes it a preferred material for medical and food processing equipment. Chemically, it is resistant to aliphatic hydrocarbons, alcohols, and dilute acids. However, it is attacked by strong bases, ketones, and chlorinated solvents. The carbon fiber reinforcement does not alter the chemical resistance profile.

Dimensional Stability and Creep Resistance

The combination of low moisture absorption, reduced CTE, and high modulus gives PSU CF10 exceptional dimensional stability. Parts machined from this material maintain their tolerances over a wide range of environmental conditions. The improved creep resistance ensures that components under continuous load do not deform over time, which is critical for structural parts like brackets and supports in precision assemblies. This stability is comparable to that required for mounting blocks in industrial equipment.

Electrical and Flammability Properties

PSU is inherently flame retardant, with a UL94 V-0 rating at 1.5 mm thickness. PSU CF10 maintains this rating. The material has a limiting oxygen index (LOI) of approximately 30%, indicating it is self-extinguishing. Electrically, PSU CF10 has a dielectric strength of 15-20 kV/mm and a volume resistivity of 10¹⁶ Ω·cm. However, the carbon fiber content makes the material slightly conductive, which can be advantageous for electrostatic discharge (ESD) applications but may require careful design for high-voltage insulation.

Typical Applications of PSU CF10

Aerospace and Automotive Components

In the aerospace sector, PSU CF10 is used for interior cabin components, such as seat back shells, tray tables, and overhead bin latches, where its low weight, flame retardancy, and dimensional stability are valued. In automotive applications, it is found under the hood for sensor housings, connectors, and structural brackets that must withstand high temperatures and chemical exposure. The material’s ability to be machined to tight tolerances makes it suitable for custom prototypes and low-volume production parts.

Medical and Food Processing Equipment

The hydrolytic stability and steam sterilizability of PSU CF10 make it ideal for reusable medical devices. Examples include surgical instrument handles, sterilization trays, and components for diagnostic equipment. In food processing, it is used for pump housings, valve components, and conveyor system parts that require repeated cleaning with hot water and detergents. The material does not support bacterial growth and meets FDA requirements for food contact in many applications.

Industrial and Semiconductor Manufacturing

In industrial settings, PSU CF10 is used for jigs, fixtures, and test equipment that must maintain accuracy under thermal cycling. The semiconductor industry uses it for wafer handling components, such as cassettes and carriers, where its low outgassing and dimensional stability are critical. The material’s resistance to aggressive chemicals used in etching and cleaning processes further extends its utility. For complex geometries, precision machining is essential, similar to the processes used for terminal blocks.

Applications Summary Table

Machining and Fabrication Considerations

Cutting Tools and Parameters

PSU CF10 is abrasive due to the carbon fiber content, so carbide or polycrystalline diamond (PCD) tools are recommended. High-speed steel (HSS) tools will wear rapidly. For turning and milling, use sharp tools with positive rake angles to reduce cutting forces. Recommended cutting speeds are 100-200 m/min for carbide tools and 200-400 m/min for PCD. Feed rates should be moderate, around 0.1-0.3 mm/rev for turning and 0.05-0.15 mm/tooth for milling. Depth of cut should not exceed 2 mm to avoid excessive heat generation.

Coolant and Chip Management

Coolant is essential to prevent heat buildup, which can cause the material to soften or melt. Use a water-soluble coolant at a concentration of 5-10%. Flood coolant is preferred over mist to ensure effective heat removal. Chips from PSU CF10 are short and powdery due to the brittle nature of the composite. Use a vacuum system or chip conveyor to remove them from the cutting area, as they can become airborne and cause respiratory irritation. Proper ventilation is necessary.

Finishing and Tolerances

PSU CF10 can be machined to tight tolerances, typically ±0.05 mm for general dimensions and ±0.025 mm for critical features. Surface finishes of Ra 0.8 µm are achievable with fine machining passes. For holes, use carbide drills with a point angle of 118-130°. Peck drilling is recommended for deep holes to clear chips. Threading should be done with thread mills or taps designed for abrasive materials. After machining, edges may be sharp due to the carbon fiber; deburring with a fine file or abrasive pad is recommended.

Comparison with Related Grades

PSU CF10 vs. Unfilled PSU

The primary difference is stiffness and dimensional stability. PSU CF10 has a tensile modulus 2-3 times higher than unfilled PSU, making it suitable for structural applications. However, unfilled PSU has better impact resistance and is easier to machine. Unfilled PSU is preferred for parts requiring high toughness, while PSU CF10 is chosen when stiffness and creep resistance are paramount.

PSU CF10 vs. PSU GF30 (Glass Fiber Reinforced)

PSU GF30 uses 30% glass fiber instead of carbon fiber. Glass fiber reinforcement is less expensive and provides good stiffness, but with a higher density (1.45 g/cm³) and lower modulus (5-6 GPa) than carbon fiber. PSU GF30 has better impact resistance than PSU CF10 but lower thermal conductivity. PSU CF10 is preferred for applications requiring lower weight and higher stiffness, while PSU GF30 is a cost-effective alternative for less demanding applications.

PSU CF10 vs. PEEK CF30

PEEK CF30 (30% carbon fiber reinforced PEEK) is a higher-performance material with a continuous service temperature of 260°C and tensile strength of 200 MPa. It also has superior chemical resistance and wear properties. However, PEEK CF30 is significantly more expensive (3-5 times) and more difficult to machine. PSU CF10 is a cost-effective alternative for applications with service temperatures below 150°C, offering good performance at a lower price point.

PSU CF10 Machining at Tuofa CNC

Precision Capabilities for PSU CF10

At Tuofa CNC Germany, we specialize in machining high-performance thermoplastics like PSU CF10. Our facility is equipped with state-of-the-art CNC milling and turning centers capable of holding tolerances as tight as ±0.01 mm. We use diamond-coated tooling specifically selected for abrasive carbon fiber composites, ensuring long tool life and consistent surface finishes. Our experienced machinists understand the unique challenges of this material, including heat management and chip evacuation, to produce parts that meet your exact specifications.

Material Sourcing and Quality Assurance

We source PSU CF10 from certified suppliers to ensure material traceability and consistent quality. Each batch is inspected for key properties such as tensile strength and modulus before production begins. Our quality assurance process includes in-process inspection and final dimensional verification using coordinate measuring machines (CMM). We provide full material certification with every order, giving you confidence in the performance of your components.

Custom Solutions and Rapid Prototyping

Whether you need a single prototype or a production run of thousands, Tuofa CNC can accommodate your requirements. Our engineering team works closely with you to optimize part designs for machinability, reducing lead times and costs. We offer rapid prototyping services with turnaround times as fast as 3-5 business days. For complex geometries, we utilize 5-axis machining to minimize setups and improve accuracy. Contact us to discuss your PSU CF10 project and receive a competitive quote.

结论

PSU CF10 is a high-performance composite material that combines the thermal and chemical resistance of polysulfone with the stiffness and dimensional stability of carbon fiber reinforcement. Its excellent hydrolytic stability, low CTE, and creep resistance make it ideal for demanding applications in aerospace, medical, and industrial sectors. While machining requires careful attention to tooling and coolant, the material can be fabricated to tight tolerances with proper techniques. Compared to unfilled PSU and glass fiber reinforced grades, PSU CF10 offers a unique balance of properties at a moderate cost. For precision components requiring reliability under extreme conditions, PSU CF10 is a superior choice. Partner with Tuofa CNC for expert machining of this advanced material.