TULLAHOMA, Tenn. — A laser process developed at the University of Tennessee Space Institute to make steel resistant to wear and rust can also be used to make long lasting identification marks on metals.
Dr. John Hopkins, associate professor of mechanical engineering at UTSI, said the new application resulted from technology originally developed to protect ship hulls, rocket launch pads, truck beds and other large metal surfaces.
Hopkins said the marking technology could be used on car parts, metal pipes such as those used in the petroleum or chemical industries, and even on aluminum cans.
The UTSI process is called Laser Induced Surface Improvement — nicknamed LISI, for which several patents are pending. High-powered lasers are used to melt a thin surface layer of material, such as steel, after spraying on an element like chromium to mix with the metal.
”It’s not a coating process,” Hopkins said. ”The layer of carbon steel becomes a new material, with properties equivalent to stainless steel.”
Identification marks that remain legible are important to industry because environments in which metals are used often are corrosive or abrasive, Hopkins said.
The identification marks can be made one of two ways — by making the mark directly on the metal with LISI or by using LISI to prepare the surface material, then painting or printing the mark on the surface.
”Aluminum parts can be very difficult to mark, so they are a good match for this process,” Hopkins said. ”It has limited impact on the part, it’s clean, and it’s durable.”
Conventional laser marking does not work well because there is little contrast between the mark and the surface material, Hopkins said.
”It might look like a silver mark on a silver background,” Hopkins said. ”Because our process changes the surface material, there is greater contrast and improved legibility.”