Flame-retardant materials: A beginner’s guide

Flame-retardant materials are vital in some 3D printing applications. They’re more thermally stable than other materials, which means the likelihood of ignition or burning is reduced.

These materials are ideal for end-use parts, replacement parts, tools, or fixtures where combustion may occur. There’s a wide range to choose from, with each offering specific benefits.

Why are flame-retardant materials important?

In some working environments, fire is a risk. Flame-retardant materials help prevent fires, or limit their spread. This gives workers valuable extra time to ensure their safety. The use of flame-retardant materials is sometimes mandatory, in order to comply with safety standards.

Common uses of flame-retardant materials

Flame-retardants are used in several different ways.

They play a key role in 3D printed electronics, ensuring that the end-products meet fire safety standards. Good examples are wires and cables, which are coated in flame-retardant plastic.

The transportation industry also relies on fire-retardant materials. 3D printed parts for airplanes, cars, and trains ensure that companies are fully compliant with safety regulations. Likewise, the construction sector uses flame-retardant materials in homes, offices, and public buildings.

What else should you know? The difference between flame-retardant and flame-resistant materials

Flame-resistant materials are designed to resist burning and withstand heat. Flame-retardant materials have a different purpose – preventing fires from starting, and limiting their spread.

Base materials

Common base materials for flame-retardancy include engineering grade thermoplastics like PA, ABS, PC, and some TPUs. PC-ABS is suitable for electronics. Some 3D printing filaments already possess flame-retardant properties themselves, such as PPS and PVDF.

Additives for flame-retardancy

Some materials are inherently flame-resistant. However, thermally stable polymers might limit print performance, and they’re also costly and difficult to process. This is why manufacturers incorporate flame retardant additives to materials, as they slow the rate of combustion, reduce smoke, and limit dripping.

Certification

Flame-retardancy is certified via UL 94, the Standard for Safety of Flammability of Plastic Materials for Parts in Devices and Appliances testing. This flammability standard was released by Underwriters Laboratories in the US.

The certifications are (from least to most flame-retardant):

HB: slow burning on a horizontal specimen; burning rate < 76 mm/min for thickness < 3 mm or burning stops before 100 mm

V-2: burning stops within 30 seconds on a vertical specimen; drips of flaming particles are allowed

V-1: burning stops within 30 seconds on a vertical specimen; drips of particles allowed as long as they are not inflamed

V-0: burning stops within 10 seconds on a vertical specimen; drips of particles allowed as long as they are not inflamed

5VB: burning stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may develop a hole

5VA: burning stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may not develop a hole

What’s important when printing with flame-retardant materials

The print process can affect the performance of the flame-retardant additive. However, the same can also be said of the design of the printed product – for example, thickness can also have impact. As such, our material partners provide pre-configured printing profiles and settings for use with Ultimaker 3D printers.

Practical considerations

Additives can be abrasive and damage the nozzle. To minimize abrasion, use a hardened metal

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