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How to Source Chopped Carbon Fiber: 24K vs 48K Comparison

by info@aramidlab.com•

Exploring Chopped Carbon Fiber: A Technical Dive into Its Applications and Specifications

Chopped carbon fiber is an engineered fiber composite composed of precisely cut carbon fiber tows, typically measuring between 3mm and 50mm in length. Designed for use in Sheet Molding Compound (SMC), Bulk Molding Compound (BMC), and injection molding applications, these fibers offer significant weight savings and robust mechanical properties comparable to continuous fiber materials. They are available in 24K and 48K filament tows, with Impact Material providing ISO 9001-certified options for various molding processes.

Executive Summary

  • Available Grades: Standard 24K, High-Volume 48K, with options for surface treatment and stabilization
  • Length Variations: Available in lengths of 3mm, 6mm, 12mm, 25mm, and 50mm to suit different molding needs
  • Mechanical Strength: Offers tensile strength of 3,500-4,900 MPa, significantly surpassing that of aluminum, while being much lighter
  • Cost Structure: Discount structures for bulk purchases: 8-12% (500kg), 15-20% (1,000kg), 25-35% (5,000kg+)
  • Minimum Order Quantity (MOQ): 100kg for standard products, 200kg for customized lengths or surface treatments
  • Lead Times: 7-10 days for standard items, 14-21 days for custom orders
  • Certifications and Compliance: ISO 9001, ISO 5079 standards, REACH compliance, with Material Test Certificates included
  • Applications: Widely used in automotive (SMC/BMC), aerospace interiors, electronic EMI shielding, and sporting goods
Industry Insight: As of 2024, the chopped carbon fiber market was valued at $485 million, with a robust annual growth rate of 13.8% projected until 2030. The automotive sector constitutes 42% of total demand, largely due to electric vehicle initiatives emphasizing lightweighting for battery enclosures and structural components. Dominating the market is SMC compression molding with a 58% share, followed by BMC at 28%, and direct injection processes at 14%.

1. Understanding Chopped Carbon Fiber

Chopped carbon fiber comprises short strands of carbon fiber, specifically created for high-efficiency molding processes like SMC, BMC, and injection molding. These strands, ranging from 3mm to 50mm, are derived from continuous carbon tows and are designed to tackle intricate geometries and swift production cycles.

The material features thousands of carbon filaments, typically 5-7 microns in diameter, bundled into tows of 24K or 48K filaments. These tows are chopped to predetermined lengths and often receive surface treatments to enhance resin adhesion and dispersion within thermoset or thermoplastic matrices.

1.1 Key Advantages

Chopped carbon fiber provides several benefits tailored for mass production:

  • Uniform Properties: The random orientation of fibers ensures consistent mechanical properties across all directions, setting it apart from unidirectional continuous fibers
  • Superior Flowability: The shorter fiber lengths facilitate excellent mold filling for intricate designs with thin walls (2-5mm)
  • Accelerated Cycle Times: Suitable for rapid compression molding cycles (60-180 seconds) and injection molding cycles (30-90 seconds)
  • Economic Efficiency: Offers a 40-60% reduction in material costs compared to continuous fiber prepreg while enabling 5-10x faster production
  • Optimal Surface Finish: Capable of achieving Class A surface finishes suitable for automotive exterior panels without additional finishing processes

1.2 Pioneering Evolution

The inception of chopped carbon fiber dates back to the 1980s, driven by the automotive industry’s pursuit of lighter alternatives to steel. Initial applications were predominantly in BMC electrical components and SMC-based vehicle panels. The 2010s witnessed significant adoption with the BMW i3 and i8 models (2013-2022), which utilized SMC forms of chopped carbon fiber for their passenger cell components, confirming the material’s viability for high-volume automotive production.

Recent innovations in surface treatment technologies and fiber length customization have expanded its applications into aerospace interiors, consumer electronics casings, and industrial machinery parts.

2. Detailed Specifications and Classification

Impact Material provides a comprehensive array of chopped carbon fiber grades tailored for specific molding demands and performance benchmarks. Recognizing these grades is essential for optimizing material choice and molding efficiency.

2.1 Specifications of Standard Grades

Parameter 24K Standard 48K High-Volume Surface-Treated Testing Standard
Filament Diameter 7.0 ± 0.3 µm 7.0 ± 0.3 µm 7.0 ± 0.3 µm ISO 11566
Tensile Strength ≥ 3,530 MPa ≥ 3,530 MPa ≥ 3,530 MPa ISO 5079
Specific Modulus 230 GPa 230 GPa 230 GPa ISO 527-4
Density 1.76 g/cm³ 1.76 g/cm³ 1.76 g/cm³ ISO 10119
Thermal Conductivity 5 W/m·K 5 W/m·K 5 W/m·K ISO 22007-4
Electrical Conductivity 6,000 S/cm 6,000 S/cm 6,000 S/cm ASTM D4496

For further detailed data and to buy chopped carbon fiber, contact our specialists.