Glow Wire Test

Safety is very important in electrical and electronic equipment. The glow wire test is used to determine the flame retardant properties of electronic products, and its purpose is to test the stability of the material during operation. Alfa Chemistry offers glow wire testing services to help you analyze the flammability of polymeric materials and explore their potential in electronic applications.

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Test content

The main test contents include the ignitability, ignition temperature, flammability and flammability index of solid insulating materials and other solid flammable materials.

Test Method

The flammability of plastics can generally be determined by the Glow Wire Flammability Index (GWFI) or Glow Wire Ignition Temperature (GWIT) methods. The glow wire itself is actually a fixed gauge resistance wire loop. During the test, the glow wire should be electrically heated to a specified temperature, and the tip of the glow wire should be in contact with the sample for the standard required time, and then the state should be observed and measured. The test range depends on the specific test procedure.

GWFI and GWIT are determined by conducting glow wire tests on test panels of a given thickness of raw material. GWFI is the maximum temperature at which a material will not ignite or self-extinguish within 30 seconds of removal of the glow wire. GWIT is the lowest temperature at which the material ignites and burns for more than 5 seconds when the glow wire is in contact with the test plate.

To pass glow wire tests, a specimen must either have no flame or glowing for more than 5 seconds while the glow wire is applied for GWIT, or have flame or glowing that extinguish within 30 seconds after removal of the glow wire for GWFI.

Sample Size

The general requirements for the dimensions of the test sample plane are as follows:

• Length: ≥ 60mm
• Width: ≥ 60mm (inside the fixture)
• Thickness: 0.75±0.1mm, 1.5±0.1mm or 3.0±0.2mm

Test Standard

IEC 60695-2-11 Flammability test for end products (GWT)

IEC 60695-2-12 Flammability test for materials (GWFI)

IEC 60695-2-13 Ignitability test for materials (GWIT)

Applications

Engineering thermoplastic polymers such as polyamides, polycarbonates, semi-crystalline aromatic polyesters and their blends are widely used as insulating materials in electrical and electronic devices. Due to the frequent use of flame retardants in the formulation of these materials, materials in these applications need to pass the glow wire test.

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Research Information

Francesco Acquasanta et al. evaluated the flame resistance and tracking resistance of glass-filled engineering polymers, blends, and flame-retardant formulations by glow wire test and comparative tracking index (CTI). In this work, neat polycarbonate passed the GWIT test but failed the CTI, while poly(butylene terephthalate) (PBT) exhibited the best balance of GWIT and CTI properties among the neat resins tested. [1]

GWIT measured at different thickness for neat polymers 30% glass fibers filled [1]

Reference

1. Francesco Acquasanta, et al. (2011). "Glow wire ignition temperature (GWIT) and comparative tracking index (CTI) of glass fibre filled engineering polymers, blends and flame retarded formulations," Polymer Degradation and Stability 96(12), 2098-2103.