While on an aircraft, wire/cable may be exposed to high temperatures while in operation. Wire/cable that softens or deforms when exposed to high temperature is a problem for the health of the aircraft and to those that maintain the fleet. Testing for delamination (the separation of layers of insulation) and blocking (adhesion either to a surface or to itself) of insulating materials ensures that wire/cable are suitably stable for particular environmental conditions.
Fluoropolymers, plastics, soften and cling to available surfaces when exposed to high temperatures. When this happens to a wire’s insulation, the expected mechanical and electrical properties of the insulation are altered. This is particularly dangerous if the insulation of a wire has partially melted and bonded to a grounded surface before being torn away when jostled and thereby exposing bare current carrying conductor.
Parameters that can be changed with this test include:
- Mandrel diameter
- Exposure duration
- Post-test assessment
For individual blocking or lamination sealing testing, as outlined in AS4373 or NEMA 27500, refer to the individual Blocking and Delamination pages