Guangzhou Kingfa Science & Technology Co., Ltd. supplies the GFABS-R series as glass-fiber-reinforced acrylonitrile-butadiene-styrene injection-molding compounds in which the suffix R10, R20, and R30 corresponds to nominal chopped glass fiber mass fractions of 10%, 20%, and 30%. The material class is not a straightforward extension of unfilled ABS. The glass strands alter the melt flow field, the solid-state elastic response, the heat deflection temperature under load, the post-mold shrinkage anisotropy, and the weld-line failure path. Because the Kingfa technical data sheet and lot certificate are the controlling documents for specification, the values discussed in this technical description are representative windows for this product class, reported against ISO methods, and are not substitutes for production-lot test data. The products are intended for injection-molded technical components in which the design requires higher tensile and flexural modulus than unreinforced ABS, lower mold shrinkage than glass-fiber polypropylene, and lower moisture sensitivity than glass-fiber polyamide.

The three grades are differentiated principally by fiber weight fraction, but this single variable changes melt viscosity, density, notched impact, surface appearance, and abrasion. The selection is not a simple monotonic upgrade from R10 to R30. R10 is used where filling of thin walls or long flow paths dominates and where the component sees moderate stress. R20 is the structural balance point for housings and brackets that must combine stiffness, process stability, and acceptable impact. R30 is selected where the part functions as a load-bearing carrier, frame, or locating feature and where the mold and machine can tolerate higher melt viscosity and higher abrasive wear. The viscosity shift is captured by melt mass-flow rate according to ISO 1133-1 under 260 °C and 5 kg load, with representative values falling from 10–18 g/10 min for R10 to 4–10 g/10 min for R30.

What distinguishes the R10, R20, and R30 grades in a load-bearing design loop?

The property progression from R10 to R30 is governed by load transfer from the ABS matrix to chopped E-glass strands. Under ISO 527-2/1A tensile testing, the representative tensile modulus for the 10% grade lies in the range 3.0–4.0 GPa; the 20% grade moves to approximately 4.5–5.5 GPa; the 30% grade reaches 6.5–8.0 GPa. Tensile stress at break follows a similar increase because the fibers bridge the crack front before matrix yielding, with representative windows of 55–65 MPa for R10, 65–75 MPa for R20, and 75–85 MPa for R30. These values must be treated as class windows rather than guaranteed minima; actual lot data can shift with matrix molecular weight, fiber sizing, colorant type, and moisture.

Flexural modulus measured according to ISO 178 is the more common design criterion for ribs and bosses. In this test the outer fiber stress is sensitive to fiber orientation at the surface. Representative flexural modulus windows are 3.2–4.2 GPa for R10, 4.8–6.0 GPa for R20, and 7.0–9.0 GPa for R30. Flexural stress at 3.5% strain follows a window of 80–95 MPa, 100–115 MPa, and 120–135 MPa across the three grades. Because glass strands align more readily in the flow direction, flexural values can be higher in flow-oriented specimens than in cross-flow specimens. This anisotropy is not captured by a single data sheet value and must be verified on prototype cavities.

Heat deflection temperature under 1.8 MPa loading, measured according to ISO 75-2/A, rises from approximately 96–100 °C for R10 to 100–104 °C for R20 and 104–108 °C for R30. The improvement is driven by the fiber network resisting deflection, but it does not imply that the matrix has a higher glass transition temperature. Continuous load at elevated temperature is still limited by the amorphous ABS phase. Notched impact moves in the opposite direction. Representative Charpy notched impact values according to ISO 179-1/1eA decrease from 8–12 kJ/m² for R10 to 7–10 kJ/m² for R20 and 6–9 kJ/m² for R30. The glass fiber increases stiffness but reduces the energy absorbed before crack propagation; designers should not use R30 in impact-dominated snaps or living hinges.

Weld-line strength is the main design limitation. In a fiber-reinforced system, the weld line contains a high concentration of fiber ends oriented perpendicular to the flow front. Tensile strength at a weld line can be 40–60% lower than the bulk tensile strength, with the largest reduction occurring at 30% fiber loading. For a load-bearing bracket, this requires moving the gate so that the weld line forms in a low-stress region, or increasing wall thickness locally to maintain a minimum effective cross-section. Testing should follow ISO 527-2/1A on end-gated tensile bars with a central weld line.

On the shop floor, the main difference between the three grades appears first as melt pressure and screw torque. Higher fiber content reduces melt flow and increases viscosity; a mold that fills with R10 at a peak injection pressure of 70 MPa may require 90–110 MPa with R30 on the same machine. This pressure increase must be evaluated against the clamp force and the projected area to avoid flash. The following starting conditions apply to a conventional hydraulic injection molding machine with a general-purpose screw of 20:1 L/D and a non-return valve.

Processing window, drying limits, and equipment wear

Moisture control is mandatory before melt processing. ABS absorbs atmospheric moisture; glass fiber sizing can also adsorb water at high relative humidity. Drying in a desiccant dryer at 80 °C for 3–4 h with a dew point of -40 °C to -50 °C is recommended to bring moisture below 0.05% by mass. Moisture above this threshold produces surface splay, reduces weld-line strength, and may hydrolyze the silane coupling agent on the glass surface, degrading fiber-matrix adhesion. If the material has been exposed to high humidity for more than 24 h, drying time should be extended to 6 h or the temperature raised only after confirming the manufacturer’s drying curve.

The melt temperature window for GFABS-R10/R20/R30 is 230–260 °C measured at the nozzle. A typical barrel profile from feed to nozzle is 210–220 °C, 230–240 °C, 240–250 °C, and 245–255 °C. Melt temperatures above 270 °C can degrade the ABS butadiene phase and cause yellowing or loss of impact. Temperatures below 220 °C can cause incomplete melting of the glass-fiber bundles, leading to visible undispersed strands and non-uniform mechanical properties.

The mold temperature should be held between 60 °C and 90 °C. The lower end improves cycle time but reduces surface replication and can freeze the flow front prematurely, increasing weld-line visibility. The upper end improves surface finish and fiber wet-out at the surface but increases cooling time. Mold temperature uniformity should be maintained within ±5 °C between cavity halves to avoid differential shrinkage and warpage.

Injection speed is selected as a compromise between pressure loss and fiber attrition. Medium to high injection speeds are generally used for R10 and R20 to maintain a continuous melt front; R30 may require reduced screw speed and higher injection pressure to avoid excessive shear heating. Back pressure is typically 0.3–0.7 MPa hydraulic to ensure melt homogeneity without destroying glass length. Screw speed should be kept in the range 30–60 min⁻¹. High shear mixing can reduce fiber length from the compounded value; since stiffness transfer depends on fiber aspect ratio, aggressive plastication lowers the effective modulus relative to the data sheet.

These starting conditions are not optimized for every mold; injection pressure depends on flow length, wall thickness, and gate geometry. A mold-filling simulation using measured melt viscosity from ISO 11443 capillary rheometry is recommended for parts with flow length-to-wall thickness ratios above 150:1.

Glass-fiber-reinforced ABS is abrasive. The screw, barrel, and non-return valve should be constructed from bimetallic or nitrided steel, and the mold should use hardened tool steel inserts at the gate and runner junctions. Without such protection, progressive screw and barrel wear causes melt temperature override and poor shot control. Gates and runners should be polished or use wear-resistant coatings if the tool is expected to run more than 500,000 cycles. The R30 grade causes the highest wear because of the higher fiber content. This is an operational boundary that must be included in total cost calculations.

When glass-fiber ABS substitutes unfilled ABS or PC/ABS in structural housings

Relative to unfilled ABS, the GFABS-R series shifts the design envelope toward higher stiffness and lower thermal expansion. A component designed in unfilled ABS may exhibit a tensile modulus of 2.1–2.8 GPa according to ISO 527-2/1A; the same wall section in GFABS-R30 can reach 6.5–8.0 GPa. Mold shrinkage according to ISO 294-4 decreases from typical unfilled ABS values of 0.4–0.7% to 0.15–0.25% in the flow direction for R30, which is useful for parts requiring tight assembly gaps. However, the notched Charpy impact of unfilled ABS is commonly 15–25 kJ/m² under ISO 179-1/1eA, while GFABS-R30 may drop below 9 kJ/m². Therefore, the substitution is valid only when stiffness or dimensional stability is the controlling requirement, not when snap-fit deflection or impact toughness governs.

Compared with PC/ABS blends, glass-fiber-reinforced ABS offers a different trade-off. PC/ABS grades can deliver notched impact values above 40 kJ/m² under ISO 179-1/1eA but often have a tensile modulus in the range 2.2–2.8 GPa. A structural housing requiring both higher modulus and lower mass may choose GFABS-R20 or R30 because the fiber reinforcement increases modulus without increasing density to the level of some mineral-filled systems. The density of PC/ABS is typically 1.10–1.20 g/cm³ according to ISO 1183-1, whereas GFABS-R30 is in the range 1.24–1.35 g/cm³. The glass fiber adds mass but less than some mineral fillers and provides greater stiffness per unit cross-section.

Compared with glass-fiber polyamide, the ABS matrix in GFABS-R grades has lower moisture absorption and more consistent dry-as-molded dimensions. Glass-fiber PA66 at 30% loading reaches higher continuous-use temperature and often higher tensile strength, but its properties shift with moisture uptake. The GFABS-R series is therefore used where moderate thermal requirements, lower moisture sensitivity, and easier processing in lower-temperature molds are more important than maximum heat resistance. The ABS matrix also avoids the high mold temperatures and pre-drying rigor associated with glass-fiber PA.

Applications for the GFABS-R series in production tooling include automotive interior structural brackets, cooling fan shrouds, HVAC vanes, washing machine structural parts, electrical enclosure frames, and appliance mounting plates. In a cooling fan shroud with a nominal wall of 2.5 mm, R20 or R30 is typically selected to maintain flexural modulus above 5 GPa at 80 °C under ISO 178 conditions. For an electrical enclosure frame mounted with steel threaded inserts, R30 is preferred when creep deformation under bolt preload at 70 °C must remain below the insertion-torque loss limit; clamped joints should be tested under ISO 16047 for preload retention. R10 is common for non-structural covers or air deflectors where thin-wall filling below 1.8 mm is required and stiffness demands are lower.

R10 is not selected for high-load structural ribs because its flexural modulus may be insufficient for snap-fit brackets that see repeated assembly loads above 60 N. R20 is the default starting point for housings that require a balance of impact and stiffness; R30 is reserved for parts where deflection under load is the primary failure mode. In a side-by-side trial on a 1,200 kN injection molding machine, an automotive interior bracket molded in R30 may exhibit 25–35% lower deflection under a 100 N static load than an R20 version at the same wall thickness, but the weld-line impact energy may be 30–50% lower. Published data for this specific configuration is limited; tool trials should confirm the selected grade.

Final validation on production equipment should include short-shot analysis, gate-seal time, and post-mold shrinkage measurement after 48 h at 23 °C and 50% relative humidity according to ISO 294-4. Warpage should be checked on a coordinate measuring machine with fixture support points defined on the drawing. The primary production failure mode for GFABS-R30 is not short cycles but delayed warpage and weld-line cracking during assembly. The mold filling pattern, fiber orientation, and gate location must therefore be fixed before transferring the part from prototype to mass production.