What Does “Self-Extinguishing” Mean?

Key Takeaways

• Self-extinguishing plastics stop burning once the ignition source is removed, improving fire safety without being completely non-combustible.

• The oxygen index measures flammability—materials with 23–27% are self-extinguishing, while 27% or higher are flame-retardant.

• Common self-extinguishing plastics such as Nylon 66, polycarbonate (PC), and PVC are widely used in electrical and electronic applications to reduce fire risk.

Overview

When it comes to flame resistance, materials generally fall into four categories:

• Non-combustible

• Flame-retardant

• Self-extinguishing

• Slow-burning

A self-extinguishing material has the ability to stop burning on its own once the external heat source is removed. While it may ignite when exposed directly to a flame, it will not continue burning once the flame is removed.

The Role of the Oxygen Index

One of the most important ways to measure flammability is the oxygen index, which is the minimum concentration of oxygen required to keep a material burning, expressed as a percentage.

• Materials with an oxygen index of 22% or lower are considered easily flammable.

• At 27% or higher, materials are classified as flame-retardant and resistant to burning.

• The 23-27% range represents self-extinguishing materials.

Examples of Self-Extinguishing Plastics

Common plastics that fall into the self-extinguishing category, based on oxygen index values, include Nylon 66, PC (polycarbonate), and PVC (polyvinyl chloride).

Why It Matters

Plastics are widely used in electronic components, electrical devices, and cable insulation, areas where fire safety is essential. Using materials that ignite easily can increase the risk of fire and potentially cause serious accidents. Self-extinguishing resins significantly reduce fire hazards, improving both safety and reliability.

Step Up Your Project with Yumoto Electric

Yumoto Electric delivers high-quality components fast, worldwide. We provide precision machining for a wide range of metals and engineering plastics. We have experience with over 200 materials including metals such as aluminum alloys, stainless steel, molybdenum, and titanium, and engineering plastics including PEEK, PPS, MC Nylon, and POM.

If you’re unsure about material selection or machining methods, we offer complimentary consultations to help optimize your design and production. For any questions, please feel free to contact us.