Material designation Dongguan Keqi Plastic ABS KQ ABS CF15A identifies an injection-molding grade of acrylonitrile-butadiene-styrene reinforced with a nominal 15 wt% short carbon fiber loading. The “CF15A” segment is read as the carbon fiber content grade modifier; however, the fiber length distribution, sizing chemistry, and ashing residue must be verified from the lot certificate. Because the manufacturer’s current datasheet is the controlling document, published data for this specific configuration is limited. The following data are therefore presented as representative ranges for comparable 15 wt% short-carbon-fiber ABS systems tested under standard conditions, not as batch-specific guarantees. Carbon fiber at this loading changes unfilled ABS from an electrical insulator to a static-dissipative composite, raises elastic modulus, lowers shrinkage, and increases heat deflection temperature under load. The corresponding penalties are lower notched impact strength, higher melt viscosity, a black surface, and increased abrasive wear on molding equipment.

How Does the Melt-Processing Window for CF15A Differ From Neat ABS on Injection Molding Lines?

Before injection molding, the granulate is typically dried at 80 °C for 4 h in a desiccant dryer with a dew point of -30 °C or lower. Residual moisture measured by Karl Fischer titration should be maintained below 0.05% to ISO 15512:2019; higher moisture contents may produce surface splay and reduce interfacial bonding at the fiber-matrix boundary. On production lines, drying hoppers with a capacity of at least twice the hourly shot weight are observed to prevent feed bridging and intermittent screw starvation. If bags are left open at relative humidity above 60% for more than 8 h, redrying is required. Regrind from sprues and runners can be added up to 20 wt% for non-critical parts, but each heat history reduces fiber length, tensile modulus, and surface conductivity. High-precision parts should use virgin material until lot-specific regrind trials are completed.

Barrel temperature settings for CF15A are commonly set 20–30 °C above those used for unfilled ABS. A typical melt temperature window is 230 °C to 260 °C; sustained barrel temperatures above 270 °C may degrade the butadiene phase and release decomposition products. The mold temperature is held between 50 °C and 80 °C. Lower mold temperatures increase orientation-induced skin-layer stiffness but reduce surface gloss and raise frozen-in stress. Higher mold temperatures within this band improve knit-line strength and fiber wetting but extend cycle time. Mold temperature uniformity should be held within ±5 °C across the cavity because carbon fiber compounds amplify differential shrinkage.

Injection screw and barrel specifications matter. A general-purpose screw with 20:1 L/D ratio can process the material for short runs, but a 20:1–24:1 compression screw with an effective check ring and bimetallic barrel is preferred. Carbon fiber is abrasive; nitrided or carbide-coated barrel and screw components are needed when cumulative throughput exceeds roughly 20 tonnes per year. Back pressure is usually 0.5–1.5 MPa and screw surface speed 0.3–0.6 m/s. Excessive screw speed produces fiber fracture, which lowers tensile modulus, impact resistance, and electrical conductivity. A ball-type or poppet non-return valve with hardened surfaces is preferred because carbon fiber can wedge a sliding-ring check valve and produce shot-weight variation.

Flow length is lower than neat ABS because the melt viscosity is higher. Typical injection pressure ranges from 80 MPa to 140 MPa. Clamp force requirements are usually 3–5 kN/cm² of projected area. Hot runner systems should use externally heated manifolds, full round runners, and gate diameters not below 0.8–1.2 mm to avoid premature freeze-off. Valve gates should open after 90% of the mold filling phase to reduce gate blush. Production observations indicate that sink marks at rib intersections occur if packing pressure is lowered below 50% of peak injection pressure, because the higher thermal conductivity of the compound freezes the gate earlier than unfilled ABS. Flashing at the parting line may also occur because the reinforced melt is less compressible than neat ABS.

Single-point melt flow rate is insufficient for mold-filling simulation. The compound is shear-thinning and fiber orientation affects nozzle pressure. Capillary rheometry at 240 °C and at shear rates of 100 s⁻¹, 500 s⁻¹, and 1000 s⁻¹ should be used to generate viscosity input data. Melt flow rate measured to ISO 1133-1:2022 at 230 °C/10 kg is useful for incoming lot control but does not predict injection pressure in thin walls below 2.0 mm.

The mechanical response of a 15 wt% short-carbon-fiber ABS compound is anisotropic and depends on fiber alignment. Table 1 gives representative values from short-carbon-fiber ABS systems measured under standard test conditions; the table is supplied for material-selection comparison and is not a guarantee for any individual lot of KQ ABS CF15A.

Impact strength is sharply reduced relative to unfilled ABS because the carbon fibers act as stress concentrators. Designers should therefore avoid molded-in thread bosses and sharp corners in load-bearing areas; add radii of at least 0.5 mm and use load-spreading washers. Tensile elongation at break drops below 3% in oriented skin layers, so snap-fit arms should be designed with reduced strain and increased hinge length. Because ISO and ASTM specimens differ in thickness, values obtained under ISO 527-2:2012 are not directly interchangeable with ASTM D638-14. ISO Type 1A specimens are 4.0 mm thick; ASTM Type I specimens are 3.2 mm thick. For carbon fiber compounds, the thinner ASTM specimen may not reflect the flow orientation present in structural sections above 4 mm. Acceptance testing should specify one specimen geometry and conditioning protocol.

Conditioning before property measurement is typically 48 h at 23 °C and 50% relative humidity to ISO 291:2008 or ASTM D618-21. Incoming lot testing should include melt flow rate, density, tensile modulus, notched Izod impact, and surface resistivity. The certificate of analysis should state the exact method, specimen type, and conditioning time. Lot-to-lot variation in carbon fiber sizing can shift melt flow rate by more than 20% without a proportional change in filler content. For that reason, a single-value property guarantee should be treated as insufficient for structural or static-dissipative applications.

Electrical, Tribological, and Dimensional Stability Characteristics in End-Use Environments

Carbon fiber at 15 wt% lowers surface resistivity from the insulating range of neat ABS into the static-dissipative range. The exact value is strongly influenced by fiber length retention and skin-layer morphology. Molded plaques with high orientation may show surface resistivity between 1×10³ Ω/sq and 1×10⁶ Ω/sq under ASTM D257-14, while through-thickness resistivity is typically higher. The material is therefore suitable for housings that require electrostatic dissipation but not for grounding-grade conductive compounds where resistivity below 1×10² Ω/sq is required. If the application must comply with ATEX/IECEx electrostatic discharge limits, testing to IEC 60079-0:2017 and IEC 60079-32-2:2015 is required; the generic surface resistivity range is not by itself a compliance statement.

Thermal expansion is lower along the flow direction. Coefficient of linear thermal expansion may be reduced from roughly 80×10⁻⁶ K⁻¹ for neat ABS to 30×10⁻⁶–45×10⁻⁶ K⁻¹ for the reinforced grade, depending on measurement direction. Creep resistance under sustained load is improved by the carbon fiber network, but secondary creep above 60 °C remains controlled by the ABS matrix. The compound should not be used for continuous loads above the HDT boundary without creep data acquired at the specific stress and temperature.

Tribological behavior differs from unfilled ABS and glass-filled ABS. Carbon fiber lowers the coefficient of friction against steel under dry sliding and increases thermal conductivity, reducing local surface temperature. However, the graphite-rich surface can produce black wear debris and may not be compatible with paints or adhesives without surface treatment. If bonding is required, plasma or corona treatment is preferred over solvent wipe alone. Silicone-based mold releases should be avoided because they may remain on the surface and reduce paint adhesion or static-dissipative performance.

Chemical resistance remains governed by the ABS matrix. Aromatic hydrocarbons, ketones, esters, and chlorinated solvents can attack the styrene-butadiene phase and cause stress cracking. The compound is not suitable for continuous contact with brake fluid, strong acids, or oxidizing agents. Published data for this specific configuration under combined chemical exposure and mechanical load is limited; component testing under service fluids is required before production release.

When Carbon Fiber Orientation and Shrinkage Anisotropy Control Part Geometry

Because short carbon fibers align in the melt flow direction, mold-filling pattern determines local modulus and shrinkage. A gate at one end of a long ribbed housing produces flow-direction modulus substantially higher than cross-flow modulus. Moldflow simulation using fiber orientation tensors and a measured fiber aspect ratio is necessary when flatness below 0.5 mm over a 150 mm length is specified. Shrinkage after 48 h conditioning is commonly 0.10%–0.30% in the flow direction and 0.35%–0.60% transverse to flow. This anisotropy is greater than that of glass-filled ABS because carbon fiber is more flexible and aligns more completely in shear flow.

If gate location, weld-line position, and packing pressure are not balanced, the difference between flow and cross-flow shrinkage produces bowing or twist. Multi-point pin gates or fan gates with widths at least 60% of local wall thickness reduce jetting. Sequential valve gating can orient fibers along the longitudinal axis in long structural parts, but the process requires simulation validation. Wall thickness should not vary by more than 25% across transitions to prevent differential cooling and fiber orientation gradients. Sink marks at thick sections may be more visible because carbon fiber reduces surface gloss and highlights local flow hesitation.

Shrinkage measurement should follow ISO 294-4:2018 or ASTM D955-21. Data collected on 60 mm × 60 mm × 2 mm plaques may not predict large parts; production-scale trials are required for parts above 500 g. Published data for this specific configuration is limited, so initial mold dimensions are often derived from shrinkage trials on a 2-cavity prototype tool before commitment to production tooling. Fiber orientation, melt-front advancement, and packing time should be recorded in each trial because they influence dimensional stability more than a single shrinkage factor.

Applications for KQ ABS CF15A are those in which the flow of neat ABS is acceptable, but stiffness, dimensional accuracy, and static dissipation must be improved without moving to a more expensive engineering resin. Typical uses include electronic housings, sensor brackets, robotic end-arm fixtures, inspection jigs, pneumatic actuator covers, and automotive interior brackets exposed to controlled cabin temperatures. It is not indicated for underhood components where continuous temperatures exceed 105 °C or for exterior parts without UV stabilization. Static-dissipative tooling and trays for electronic assembly are common uses, provided the surface resistivity is verified on the molded part rather than assumed from pellet data.

Compared with 20 wt% glass-fiber ABS, the carbon fiber grade offers a lower density at equivalent tensile modulus and provides static-dissipative surface properties. However, glass-filled ABS is lower cost, naturally electrically insulating, and usually available in lighter colors. Compared with unfilled ABS, the main differences are higher tensile and flexural modulus, lower shrinkage, lower impact toughness, higher melt viscosity, and a black surface. Compared with PC/ABS blends, the carbon fiber ABS grade generally has lower notched impact strength and lower HDT than heat-resistant PC/ABS grades but higher tensile modulus and lower surface resistivity. Compared with 15 wt% carbon-fiber PA66, the ABS matrix absorbs less moisture, processes at lower melt temperatures, and is less sensitive to hydrolysis, but it has lower continuous-use temperature and lower chemical resistance to aromatic hydrocarbons.

The compound has defined operational boundaries. It must be kept dry before molding; exposure to relative humidity above 60% for more than 8 h may require redrying. It is not a food-contact grade and should not be assumed compliant with FDA 21 CFR 177.1020 unless the supplier provides a specific regulatory letter. It is not inherently UV-stabilized. The material should not be used with amine-based mold release agents or certain unsaturated ester lubricants that can interfere with fiber sizing adhesion. Carbon fiber surfaces may interfere with electromagnetic interference gaskets if surface resistivity is above 1×10⁴ Ω/sq; continuity testing is required. RoHS recast 2011/65/EU and REACH 1907/2006 compliance must be confirmed with the supplier’s lot-level documentation; generic ABS compliance does not automatically include the carbon fiber sizing and binder system. Batch-to-batch fiber sizing changes may alter melt flow rate and conductivity, so all production parts should be qualified with incoming lot sampling for melt flow rate to ISO 1133-1:2022, density to ISO 1183-1:2019, and notched impact to ISO 180:2023.