Devdas Shetty

Modeling utility for percussion laser drilling – Experiment vs theory

Laser percussion drilling is widely used in the aerospace industry to produce cooling holes in jet engine components. A variety of theoretical models have been developed to predict the outcome of the drilling process. However, to utilize these models often requires sophisticated software to perform the required numerical analyses. We developed a simple and easy- to-use computer utility called DREAM (Drilling Routine for Estimating, Analyzing and Modeling). DREAM is a free-standing, MATLAB-based design that offers a convenient and flexible way to predict a variety of drilling process outcomes and can be executed on any Windows-based personal computer. This paper discusses new features that have been incorporated into the 2007 Beta release.Laser percussion drilling is widely used in the aerospace industry to produce cooling holes in jet engine components. A variety of theoretical models have been developed to predict the outcome of the drilling process. However, to utilize these models often requires sophisticated software to perform the required numerical analyses. We developed a simple and easy- to-use computer utility called DREAM (Drilling Routine for Estimating, Analyzing and Modeling). DREAM is a free-standing, MATLAB-based design that offers a convenient and flexible way to predict a variety of drilling process outcomes and can be executed on any Windows-based personal computer. This paper discusses new features that have been incorporated into the 2007 Beta release.

Optimization of parameters for effective welding of aerospace components

This paper reports research results in two areas. First, it defines laser-welding processes for jet engine turbine components and specifies the steps and parameters for that process. Secondly, it proposes an optimization routine aimed at finding optimum welding procedures and parameters since laser welding is not commonly used in aerospace applications. This paper proposes guidelines for laser welding of nickel-alloy sheet metal up to 0.061” in thickness. These guidelines are based in part on processes previously reported in the literature including comparisons with conventional welding technologies.One area where laser welding may prove advantageous is in improving the cost and quality of combustor component manufacturing (Figure 1). The results of a feasibility study of laser welding including quality, material integrity, and economic benefits are included. Recommendations in the area of design guidelines to maximize the benefits of laser welding in the manufacturing process are provided.This paper reports on the use of a fiber laser for welding using three control factors: optical power, welding speed and minimum spot diameter for an Inconel 625 sheet. Using a Taguchi design of experiment model, laser weld outcomes are analyzed and optimal weld porosity results are reported.This paper reports research results in two areas. First, it defines laser-welding processes for jet engine turbine components and specifies the steps and parameters for that process. Secondly, it proposes an optimization routine aimed at finding optimum welding procedures and parameters since laser welding is not commonly used in aerospace applications. This paper proposes guidelines for laser welding of nickel-alloy sheet metal up to 0.061” in thickness. These guidelines are based in part on processes previously reported in the literature including comparisons with conventional welding technologies.One area where laser welding may prove advantageous is in improving the cost and quality of combustor component manufacturing (Figure 1). The results of a feasibility study of laser welding including quality, material integrity, and economic benefits are included. Recommendations in the area of design guidelines to maximize the benefits of laser welding in the manufacturing process are provided.This paper repo...

Optical inspection of laser drilled cooling holes in jet engine blades

The need for improved thermal efficiency of jet engines has led to changes in the design of combustor turbine blades. Modern turbine stage inlet temperatures now exceed the melting point temperatures of turbine blade materials. Super alloys, based on nickel, have been developed for use as blades, guide vanes, afterburners etc. To combat and avert blade failure caused by excessive operating temperatures, film cooling has been incorporated into blade design. In film cooling, cool air is bled from the compressor stage, ducted into internal chambers of the turbine blades, and discharged through small holes in the blade walls. This provides a thin, cool, insulating blanket along the external surface of the turbine blade. Large numbers of shaped holes have allowed designers to maximize the cooling effect.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 captures an image of the sample and displays the size and shape of each entrance hole. To measure the presence of a bottom, a second XYZ inspection stage is used. Using a small collimating tube, a micro-beam illuminates a drilled hole in a pre-programmed fashion. Depending on the level of reflected intensity and where it occurs, the presence of a hole bottom is determined. The optical inspection system consists of a laser, motorized micro-positioning stages, collimating tubes, vision system, data acquisition software and a customized fixture for manipulating the samples.The need for improved thermal efficiency of jet engines has led to changes in the design of combustor turbine blades. Modern turbine stage inlet temperatures now exceed the melting point temperatures of turbine blade materials. Super alloys, based on nickel, have been developed for use as blades, guide vanes, afterburners etc. To combat and avert blade failure caused by excessive operating temperatures, film cooling has been incorporated into blade design. In film cooling, cool air is bled from the compressor stage, ducted into internal chambers of the turbine blades, and discharged through small holes in the blade walls. This provides a thin, cool, insulating blanket along the external surface of the turbine blade. Large numbers of shaped holes have allowed designers to maximize the cooling effect.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 desi...

Financing strategies used by small and mid-sized firms using laser manufacturing technology to supply the aerospace industry

The aerospace industry is comprised of a few large manufacturers and a large number of smaller supplier firms that manufacture components used in the production of aircraft. A key challenge for these smaller firms is the need to remain both economically viable and globally competitive. One of the ways in which they have sought to achieve those objectives is through the adoption of laser manufacturing technology that typically requires substantial investment in equipment, training, and safety. This paper will focus on the financial strategies used by small to mid-sized firms using lasers in their manufacturing processes. It will identify and discuss the merits of major sources of capital, both public and private, as well as gaps in funding. It will also discuss why firms in this industry tend to use certain types of funding while avoiding others. These decisions have implications for the capital structures of these firms as well as for their potential for growth.The aerospace industry is comprised of a few large manufacturers and a large number of smaller supplier firms that manufacture components used in the production of aircraft. A key challenge for these smaller firms is the need to remain both economically viable and globally competitive. One of the ways in which they have sought to achieve those objectives is through the adoption of laser manufacturing technology that typically requires substantial investment in equipment, training, and safety. This paper will focus on the financial strategies used by small to mid-sized firms using lasers in their manufacturing processes. It will identify and discuss the merits of major sources of capital, both public and private, as well as gaps in funding. It will also discuss why firms in this industry tend to use certain types of funding while avoiding others. These decisions have implications for the capital structures of these firms as well as for their potential for growth.