Non-Intrusive Direct Part Marking

DoD policy requires a 2-dimensional data matrix machine-readable, item unique identification (IUID) as defined in MIL-STD-130 on expensive and critical aircraft components such as jet engine parts. Laser marking is ideal because it requires no special fixture, it can be done from an angle on complex surfaces, the size of the mark can be adjusted to fit the available space, and the beam doesn’t wear out. But marking with traditional, long pulse lasers (with pulses of duration longer than 1 picosecond) creates a heat-affected zone (HAZ) from which cracks can initiate and result in catastrophic failure. This program will demonstrate the use of a femtosecond pulse duration laser to mark high value, heat-sensitive aircraft components. In addition to the above mentioned benefits, marking with femtosecond pulses of light will eliminate HAZ and structural changes to the base material, making possible the use of laser marking of fatigue-critical rotating engine components. The process is highly deterministic and highly repeatable, thus ensuring that the mark itself is reliably produced on the material. Phase I of this program will identify an efficacious machine-readable dot geometry and the protocol needed to produce a UIUD mark with a femtosecond laser. BENEFIT: The marking of high-value components during manufacture and repair history would be useful in military and commercial jet engines and in industrial gas turbine that generate electricity. Especially useful is the possibility of marking the thermal barrier coating (TBC) on jet engine blades without inducing spalling or delamination from the underlying superalloy. More broadly, the ability to mark components with an extremely small 2-D data matrix IUID that is nearly invisible to the naked eye would be useful in ballistic identification of munitions as a means of monitoring their degradation over time and/or the illegal trafficking in these items around the globe.