Abstract
One of the most difficult issues in the disposal of the vehicle at the end of its life, is the recycling of the wiring harness.
The complex nature of the task of electrical distribution in the vehicle means that it contains a wide variety of materials. Resulting from this the separation and recycling of each of the materials has so far proved not to be an economical proposition.
Currently the most practical recycling option at the end of the vehicles life is to burn the harness, using the waste heat generated from the combustion of the plastics, and recycle the metals (mainly copper) that remain after the combustion.
One of the main polymers used in todays harness construction is PVC and this poses environmental problems with the disposal method described above. Hydrogen chloride will always be liberated and the presence of highly toxic furans and chlorinated aromatics such as dioxins has been frequently recorded at unacceptably high concentrations during incineration.
PVC tape is the main wrapping method used in wiring harness construction today and will need to be replaced with an economic alternative to enable the transition to an easily recycled harness. This paper outlines the development of a practical alternative to PVC adhesive tape that is easy for the harness manufacturers to use, performs well over a variety of application extremes for the life of the vehicle and gives no issues when the harness is recycled.
The requirement of the harness makers is to have a tape with smooth easy unwind and easy tear to help minimise the risk of Repetitive Strain Injury within the manufacturers workforce. The harness also needs to be flexible for easy installation in the vehicle.
During the life of the vehicle the tape must continue to perform its function when exposed to heat, cold, vehicle fluids, and abrasion and not contribute to fogging within the passenger compartment. These product performances are outlined in the new SAE specification for harness covering materials that is due for issue in 2002.
In order to ensure safe recycleability, the combustion products from the new tape have been analysed and while oxides of carbon and nitrogen are produced as in a typical clean combustion, the combustion products are totally halogen free and no noxious gases are produced.
In summary this paper describes a recyclable, practical and cost effective alternative to PVC tape that is designed to meet existing and future specifications whilst incorporating unique benefits over existing materials.