BASF 3D Ultrafuse ABS Fusion+ is an acrylonitrile-butadiene-styrene feedstock supplied as a monofilament for material extrusion processes defined in ISO/ASTM 52900. The product belongs to the Ultrafuse family formerly distributed under BASF 3D Printing Solutions and now handled within the Forward AM portfolio. It is available in 1.75 mm and 2.85 mm diameters with a supplier-listed diameter tolerance of ±0.05 mm. The compound is unfilled and is not a fiber-reinforced grade; the butadiene rubber phase provides impact toughness below the styrene-acrylonitrile glass transition temperature near 105 °C. The material is therefore positioned as a general-purpose technical ABS filament with modifications intended to reduce the known FFF failure modes of interlayer delamination and platform warp. Its model designation ABS Fusion+ distinguishes it from standard ABS grades and from filled or high-temperature styrenic blends in the same Ultrafuse line.

Filament manufacturing begins with pellet feedstock processed through a twin-screw compounding line having an L/D ratio typical of 30:1 to 40:1, followed by melt filtration and air-cooled filament drawing. Closed-loop laser micrometer feedback is used to control diameter variation, and winding tension is held constant to prevent spool cross-overs on reverse Bowden extruders. Batch-to-batch variation in ABS grades usually appears as changes in melt viscosity and die swell, which in turn influence the effective extrusion width at a given nozzle temperature. For this reason, a new spool should be calibrated with an extrusion multiplier test using a single-wall cube and a measurable road width before production parts are started.

When Enclosure Temperature Is Insufficient, What Processing Defects Emerge?

In open-frame Cartesian and CoreXY machines, printed ABS parts develop internal cooling stress as the extrudate solidifies below the styrene-acrylonitrile glass transition. The outer road surface contracts while the interior remains above the solidification threshold. If the heated bed is maintained at 90–110 °C but the ambient chamber remains below 35 °C, parts with X/Y dimensions above 150 mm can exhibit corner delamination and first-layer fissure growth. The failure mode is most severe at acute corners with radii below 5 mm because stress concentration scales inversely with corner radius. On a production run using a 0.4 mm brass nozzle at 60 mm/s, the upper layers act as a constrained skin that imposes tensile stress on the bed-adhesion interface. Printed ABS Fusion+ is formulated to reduce this differential contraction relative to general-purpose ABS, but the reduction is not a replacement for thermal management. Field data from open-frame printers show that a raised brim of 8–10 mm width at 0.1 mm separation reduces edge peel by increasing the bonded area between the first layer and a polyimide or PEI substrate. For parts taller than 100 mm, a passive enclosure maintaining 35–45 °C ambient temperature stabilizes the solidification rate and prevents mid-part delamination along the Z-axis. The use of an unheated chamber for large flat geometries remains an operational boundary, not a recommended production condition.

The first-layer deposition window is narrower than for unfilled general-purpose ABS. Bed temperature below 90 °C reduces adhesion to polyimide surfaces and increases the probability of corner lift, while bed temperature above 110 °C can soften the lower layers and produce a condition known as elephant-foot at the build platform interface. First-layer speed should be reduced to 20 mm/s or lower on unenclosed printers, with first-layer height set to 0.20–0.25 mm to create a more compliant road profile. The nozzle temperature for the first layer may be increased by 5 °C above the body profile to promote wet-out on the build surface.

Drying and Melt Residence Limits

ABS Fusion+ absorbs sufficient moisture to generate observable processing defects when spools are stored in an uncontrolled environment. The supplier-recommended drying schedule is 80 °C for 4 h in a forced-air convection oven. Spools exposed to relative humidity above 60% for more than 24 h should be dried before printing. Moisture evolves during melt deposition, producing surface fogging and interfacial porosity between adjacent roads. Unlike polyamides, ABS does not undergo rapid hydrolytic main-chain scission at printing temperatures, but absorbed water increases the energy demand at the nozzle and causes irregular filament swell at the die. This swell changes the effective extrusion width and degrades dimensional accuracy. After drying, spools should be stored at 15% RH or lower or in a sealed desiccant container. A dry-box purge with silica gel or molecular sieve is sufficient for continuous use.

Melt residence limits are not published as an absolute value, but prolonged nozzle dwell above 260 °C degrades the butadiene phase and produces brown discoloration, acrid odor, and notch sensitivity in printed test coupons. The practical maximum continuous idle time at print temperature should be kept below 30 min, after which the melt should be purged. If the hotend thermistor drifts by more than ±3 °C, the melt temperature may exceed the intended window even when the control setpoint remains unchanged.

The recommended body nozzle temperature range is 240–260 °C for a 0.4 mm nozzle. Larger nozzles above 0.6 mm may require the upper end of the temperature range because volumetric flow rate increases and heat transfer from the hotend wall to the melt must compensate for shorter residence time. The bed temperature range of 90–110 °C is at the upper end of standard ABS settings. The typical print speed window is 30–60 mm/s for a 0.4 mm nozzle at 0.2 mm layer height. Under these conditions, the nominal volumetric flow rate is 4.8 mm³/s. Exceeding the hotend volumetric capacity produces under-extrusion, intermittent road width, and poor interlayer coalescence. For a standard E3D-style all-metal hotend without a high-flow heat break, the volumetric limit may fall between 10 mm³/s and 15 mm³/s, so speed increases must be matched to the melt zone design.

Active part cooling should remain off for solid layers to allow road interfaces to remain above the coalescence threshold. For unsupported overhangs, cooling fan duty up to 20% can be used, but higher airflow can quench the surface and reintroduce differential shrinkage. For bridges, fan duty may be increased only if bridging length exceeds 10 mm; bridge speed should be raised to 60 mm/s and extrusion multiplier reduced to 0.95 to tension the extrudate.

If Production Demands Low-Warp ABS Without Active Chamber Heating

Ultrafuse ABS Fusion+ is selected in production environments where a general-purpose ABS cannot meet warp rejection limits, but an actively heated chamber is not available. The material permits bed adhesion on polyimide, PEI, or ABS slurry surfaces at 100 °C. The lower warp tendency reduces reject rates for flat parts with perimeter length above 500 mm, provided the first-layer geometry includes corner chamfers or radii above 5 mm. However, PC/ABS blends generally retain higher deflection temperatures under load according to ISO 75-2 and are preferred when parts see continuous service above 90 °C. For outdoor exposure, ASA is preferred because the butadiene phase in ABS is inherently sensitive to ultraviolet degradation and can exhibit yellowing, chalking, and embrittlement. These substitutions should be governed by the mechanical loading regime and environmental exposure, not by process convenience alone.

In comparison with standard ABS filament, the Fusion+ grade is designed to address the anisotropy observed under ISO 527-2. In FFF parts, ZX tensile strength can be 50–70% lower than XY tensile strength because road-to-road adhesion is limited by polymer interdiffusion at the interface. ABS Fusion+ is formulated to broaden the coalescence window between deposited roads. Manufacturer datasheets report tensile, flexural, and impact values using printed specimens conditioned at 23 °C and 50% RH, but published data for all raster configurations is limited. Designers should request the supplier technical data sheet and perform boundary testing on the target printer because Z-strength depends on nozzle temperature, layer height, and chamber thermal uniformity. A part printed at 240 °C with 0.1 mm layers may exhibit higher Z-strength than the same geometry printed at 260 °C with 0.25 mm layers due to longer inter-road contact time and higher void closure.

For mechanical property comparisons, the following test methods apply to this ABS grade when specimens are printed and conditioned according to the material data sheet.

Mechanical property data for this specific filament are best interpreted through a standards matrix rather than raw values without print context.

Chemical compatibility follows the solvent-resistance profile of general-purpose ABS. Ketones such as acetone and methyl ethyl ketone, esters, and chlorinated solvents swell or dissolve the surface. Acetone vapor smoothing is frequently applied to ABS parts to reduce layer lines, but thin walls below 2 mm may develop stress crazing after extended vapor contact. Alcohol-based cleaners are generally non-solvent for ABS and are suitable for light surface removal. During melt extrusion between 240 °C and 260 °C, traces of styrene and acrylonitrile may evolve; local exhaust ventilation should keep styrene exposure below the OSHA 8-hour permissible exposure limit of 100 ppm. The material is not represented as food-contact compliant under FDA 21 CFR 177.1020 or the corresponding EU migration framework without end-use validation. The printed article, pigments, additives, and print surface contamination must be assessed before any food or medical application. For industrial use, the safety data sheet and REACH registration status should be confirmed with the supplier before deployment in a production cell. Published data for some application-specific configurations is limited, and verification on the target equipment remains a mandatory control step.