SMALL DIAMETER WIRE MARKING FOR LIGHT WEIGHT ELECTRICAL INTERCONNECTIONS SYSTEMS

Aircraft designers are reducing wire and insulation weight in the newest generations of high technology, light weight helicopters by using smaller diameter wire. Current aircraft wiring assembly processes require that each wire be uniquely identified. This requires that aircraft manufacturers develop processes for identifying smaller wires. This paper and presentation discusses wire marking technology trends within the aircraft industry. The strengths and weaknesses of the machinery and processes for hot stamp marking, inkjet marking and laser marking are presented. Technical limitations for inkjet marking are discussed to provide a practical lower limit for inkjet character size. The effect of orifice size and drop size are evaluated. The process that excimer laser wire marking uses to darken pigments and produce characters is explained. The theoretical lower limit for excimer laser wire marking is the grain size of titanium dioxide pigments and is well below the limit of human assemblers to identify characters. The practical lower limits of character sizes that can be read by assembly personnel are identified. Extensive statistical data for hot stamp marking depth is presented that identifies the future direction that hot stamp marking must take if it is to be a viable process for marking small diameter wire.