Product Code: ICAL06_1402

Optical Inspection of Laser Drilled Cooling Holes in Jet Engine Blades
Authors:
Devdas Shetty, University of Hartford; West Hartford CT USA
Nikolai Nazaryan, University of Hartford; West Hartford CT USA
Tom Eppes, University of Hartford; West Hartford CT USA
Claudio Campana, University of Hartford; West Hartford CT USA
Jun Kondo, University of Hartford; West Hartford CT USA
Presented at ICALEO 2006

The need for improved engine efficiency of jet engines has led to changes in the design of combustor turbine blades. To combat and avert turbine blade failure caused by excessive operating temperatures, film cooling has been incorporated into blade design. Much research in recent years has been focused on improving the manufacturing cost and quality of laser-drilled holes. At present, it is necessary to inspect components for defects commonly associated with laser drilling such as taper, barreling, presence of recast layers and micro-cracks. This paper explores a new design for inspecting turbine blade cooling holes. In the paper, we examine the inspection techniques currently in use and present a novel optical technique as an alternative. Our design consists of two stages of inspection, each optically based. The first stage uses a camera positioned axially in line with a laser beam. A sample is mounted on an XY micro-positioning stage, and a vision system. To measure the presence of a bottom, a second XYZ inspection stage is used. The optical inspection system consists of a laser with micro-positioning stages, vision system, data acquisition and a customized fixture for manipulating the samples.