Material Selection Requirements
Flammability rating of a material measure the extent to which it will support combustion. Flammability standards help designers understand potential risk of combustion of a material they intend to use. Because fire is a common public safety concern, several agencies are involved with flammability standards and test procedures for plastics. Most material suppliers provide flammability data for their materials according to Underwriters Laboratories rating. However ASTM, Federal Aviation Administration and U S Department of Transportation (Motor Vehicle Safety Standards) also have flammability standards. Flammability ratings are usually listed with a minimum wall thickness specified. These ratings are very helpful in material selection. However, accurately predicting the potential fire hazard of a specific part is quite difficult based on these ratings. For example, the actual part thickness may be different than the test specimen thickness. Also, some other indicators, such as smoke and toxic emissions etc., are not measured in these tests. National Bureau of Standards specifies test requirements that deal with this issue. Flame retardant chemicals are commonly added to thermoplastic resins to make fire retardant parts. Some flame retardants packages may contribute to the increase of toxicity of the emissions. Choose your resin carefully to avoid such flame retardants. To learn more about flammability issues with thermoplastic resins, access our ABCs of Material Selection guide on this Web Site. |