Laser-Based Repairing of Turbine Airfoils and its Economical and Environmental Impact

By J. Michael Wilson

Purdue University

Replacement costs for high value engineering components are very high due to long lead times and special tool required for processing high strength materials.  Laser direct deposition provides an attractive and cost effective means for repairing or remanufacturing high value engineering components.  Traditional repair processes are limited in applicability and bond strength.  With the emergence of Laser Direct Deposition (LDD) technologies the limitations of traditional repair processes are overcome.

Remanufacturing utilizes existing material resources to restore a component to “as new” condition or better.  Remanufacturing can produce a part better than the original by incorporating more advanced materials or by adapting to the improved design.  It also reduces waste and extends the life of the component. Laser-based remanufacturing provides a means to restore parts that were previously deemed “non-repairable”.

One difficulty in laser based remanufacturing is how to determine the missing geometry because of a void or defect.  A complete reverse engineering process was used to generate a parameterized geometric model required for LDD based repair.  The process starts by taking a laser scan of the defective are and building a mesh.  Then extract Prominent Cross Sections (PCS) from the non-defective region and reconstruct the repaired model in CATIA™ by interpolating the damaged region.  Finally, extract the Boolean difference to obtain the repair volume. The repaired blade matched the geometry of the original blade with a maximum deviation of 0.145 mm from the nominal model.

This study demonstrates the successful repair of defective voids in turbine airfoils based on a new semi-automated geometric algorithm and a direct laser deposition process. A Boolean difference between the original defective model and the final reconstructed model yields a parameterized geometric representation of the repair volume. The experimental results of this method demonstrate the effectiveness of laser direct deposition in remanufacturing and its ability to adapt to a wide range of part defects.

A Life Cycle Assessment (LCA) on the energy and environmental impacts showed that LDD only required 7.6% of Carbon footprint over replacing with a new part.

Re manufacturing saves energy and is better for the environment than producing a new investment casted component.  In addition, LDD remanufacturing can accurately restore the shape and strength of high value engineering components.

About the Author
Steven Glover is a proud member of the LIA staff. When he is not at work he is actively involved in several charitable efforts.
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