New laser assisted process offers better drilling for advanced materials

Hossein Mohammadi

Keeping up with new technology isn’t easy. And keeping up with the materials to make that new technology possible isn’t easy either. Everyday products are becoming increasingly sophisticated. Cell phones are getting ever slimmer. Cars are driving themselves. Drones may soon be delivering packages. All of them need more energy efficiency, which means more compact designs using new materials that usually are stronger and harder.

“New advances in technology demand new processes with higher capabilities,” said Hossein Mohammadi, a doctoral student in mechanical engineering at WMU’s College of Engineering and Applied Sciences. He has been working on a new drilling process for more than two years. Called laser augmented diamond drilling, it is a hybrid process that melds traditional mechanical drilling with laser-softening, allowing for increased capabilities in drilling with advanced materials such as ceramics, reinforced composites, and ceramic matrix composites. He recently filed a patent for the process, in which a laser shines through a diamond – typically a synthetic diamond – to allow for more precise and effective drilling of hard, brittle or more challenging materials.

"Most parts require ‘holes’ for function, assembly or to accommodate fasteners,” said Dr. John Patten, Mohammadi’s faculty advisor.  “Holes in general -- and drilled holes in particular -- are one of the most common features in manufactured components.  Producing precision holes in nominally hard and brittle materials, without flaws, is presently a challenge. It’s time consuming, costly and most often requires post processing. The laser augmented diamond drilling process addresses all of these issues.”

 “Ceramics, semiconductors and composites have a variety of applications in industry and often need to be drilled to a high level of accuracy,” Mohammadi said. “But because of their physical properties, it can be difficult to drill holes free of fractures, surface and subsurface damage, cracks and micro-cracks, while maintaining good edges and high surface quality,” he said. In addition, drill bit life in regular drilling of these materials is very low, making it cost-prohibitive, he said.

Mohammadi said the laser diamond drilling process could have applications in a wide range of industries, including electronics, automotive and aerospace. He pointed to cell phones as an example. “Phones are continually getting streamlined and thinner, but traditional materials cannot adequately make the body strong enough. The newer, advanced materials available are extremely challenging to cut and shape. A regular drilling process either cannot make a hole in these advanced materials or can only do so at a very high cost.” He noted that in the automotive industry, vehicles produced today are lighter, using materials such as composites, which have high mechanical properties. “Soon, most of the parts in cars will be replaced with these new materials,” he said.

Mohammadi has presented his prototype and process to industry and in conferences and is optimistic about its potential.