ABS-FR (Flame Retardant)

ABS-FR (flame-retardant ABS) is regular ABS blended with flame retardants that make the part self-extinguishing: once the flame is removed, burning stops within seconds and the plastic does not drip flaming droplets. Most common grades are certified to UL94 V-0 — the strictest consumer self-extinguishing class. ABS-FR prints almost exactly like regular ABS, and you reach for it whenever a part has to meet fire-safety requirements.

What it's good for

• Electronics and power-supply housings, where a part may heat up or arc
• Sockets, breaker panels, terminal boxes and other electrical hardware
• Parts for rail and public transport with flammability requirements
• Prototypes of products that will later be certified for fire safety

Where not to use it

• Decor and toys — there is no point paying for flame retardants; use plain ABS, PLA or PETG
• Parts that contact food — flame retardants are not intended for that
• Printing without an enclosure and ventilation — ABS-FR warps and smells just like any ABS
• When you need maximum impact strength — flame retardants slightly lower toughness versus pure ABS

How to print

• Nozzle temperature: 240–265 °C
• Bed temperature: 90–100 °C
• Enclosure: mandatory — ABS-FR warps and cracks badly in a draft
• Cooling: minimal or off — fan cooling hurts layer adhesion and causes delamination
• Speed: 40–80 mm/s, same as regular ABS
• Adhesion: glue stick or ABS slurry on the bed; use a brim for large parts
• Nozzle: a plain brass nozzle is fine — the flame retardants are not abrasive, so no hardened nozzle is needed

Drying and storage

ABS-FR is mildly hygroscopic — it picks up moisture more slowly than nylon or PC, but it does get damp after long open-air storage. Wet filament bubbles at the nozzle, gives a rough surface, and loses strength.

• Drying: 70–80 °C for 4–6 hours
• Storage: airtight box with silica gel, especially in humid climates
• Signs of moisture: crackling and steam while printing, bubbles in the strand, a rough cloudy surface

Pros and cons

• Self-extinguishing (UL94 V-0) — does not sustain a flame and does not drip fire
• Keeps all the working properties of ABS: heat resistance, impact strength, easy machining
• Prints just like regular ABS — no exotic settings required
• Not abrasive — a plain brass nozzle is enough

• Needs a closed enclosure and ventilation — warps badly and fumes while printing
• More expensive than regular ABS because of the flame retardants
• Smell while printing is sharper than plain ABS, and flow behaves slightly differently
• Flame retardants slightly reduce impact toughness versus pure ABS