THE INFLUENCE OF PULSE SHAPE ON HOLE GEOMETRY DURING Nd:YAG LASER DRILLING OF STAINLESS STEEL SHEETS

Document Type : Original Article

Authors

1 Graduate student, Dpt. of Machine Design and Production, MTC, Cairo, Egypt.

2 Ph.D., Head of Dpt. of Machine Design and Production, Mit, Cairo, Egypt.

3 Professor, Dean of Faculty of Technology, Workers University, Cairo, Egypt.

Abstract

Laser drilling has been used for making large number of cooling holes in gas turbine engine industry due to its benefits in saving cost and time. In single pulse laser drilling, a hole can be formed in thin metallic sheets by one laser pulse with enough energy, in which the hole making may take just few milliseconds. Pulse shaping is one of the important factors that could affect the hole characteristics. In the present study; three types of pulse shapes; rectangular, ramping up, and ramping down, with pulse width of 2 ms were used to drill through holes in 1 rnm thick stainless steel sheets. Scanning electron microscope (SEM) was used to capture the necessary images of the laser-drilled holes at the different pulse shapes. An image processing technique was applied to identify the spatter around the drilled holes. It was also used to calculate the inlet hole diameter and its associated spatter deposition area. Optical microscope was utilized to measure the exit hole diameter. The hole taper was evaluated by calculating the inlet to exit hole diameters ratio. Finally, the prescribed holes are reproduced using two pulses having the same total energy as the one pulse used before. A comparison between the two drilling techniques was established. It was found that the pulse shaping could have a remarkable effect on the measured hole configurations when the two types of laser drilling were applied on the used stainless steel sheets. Also, the two drilling techniques produced holes with different final geometry.

Keywords

Files

Share

How to cite

Statistics