Jul 19 2007
Researchers at Purdue University are perfecting a technique for manufacturing parts that have complex shapes and precision internal features by depositing layers of powdered materials, melting the powder with a laser and then immediately machining each layer.
The new method can be used for creating parts made of advanced materials such as ceramics, which are difficult to manufacture and cannot be machined without first using a laser to soften the material, said Yung Shin, a professor of mechanical engineering and director of Purdue's Center for Laser-Based Manufacturing.
Because the technique enables parts to be formed one layer at a time, it promises new industrial applications for manufacturing parts containing myriad internal features, he said.
"For example, if you are making a pump, you may have a lot of internal channels and components made of different materials," Shin said. "Since you can deposit layer by layer, you can create very accurate geometrical shapes, actually building this part from the ground up instead of machining different components and then assembling them into a pump. We can make parts that contain a metal layer followed by a ceramic layer, and so on, which is important for creating components for the electronics industry and for other applications."
Although the basic "laser deposition" technique is not new, the Purdue researchers have increased its precision by adding the machining step.
"We have improved the method so that it's about 20 times more accurate by adding the ability to machine the part while it is being formed," Shin said. "We have developed a facility that can actually deposit the powder, heat it with the laser and machine it at the same time."
The new technique could be critical for manufacturing certain kinds of ceramic components that are not produced in large enough quantities to justify the expense of designing costly molds called dies. Components made in small lot sizes might be produced far more economically by machining instead of using dies. But there has been no practical way to machine the brittle ceramic materials economically with the high precision needed for many applications.
Purdue's research program is one of a handful of efforts internationally to develop such a system, which could be used to produce small quantities of parts faster than currently possible, Shin said.
"From start to finish, beginning with just a design, we can have the job completed in a couple of days, compared to several weeks for a conventional manufacturing operation," he said.
Researchers at the Purdue center are able to precisely control the power and temperature of the laser and also have developed mathematical models for the procedure, steps critical for the technology's practical application. The researchers also have created a graphical user interface for the technique's software.
Laser deposition has been used commercially to create parts that have complex shapes, such as gun barrels, jet engine turbine components, spare parts for various military equipment, connecting rods for engines, automotive brake components, synthetic teeth, artificial knee joints and next-generation computer memory devices. However, in current laser deposition, the part is machined after it is completely formed, meaning the technique cannot be used to create accurate internal features, and it is mostly limited to manufacturing metal parts, Shin said.
"But this integrated process can be used for fabricating ceramic parts as well, and parts that have internal features," Shin said. "This is important because advanced ceramics are exceptionally hard, can withstand high temperatures and do not wear out as quickly as metals."
Demand for advanced ceramics, a $7.8 billion industry in the United States alone, is expected to grow 7.4 percent annually through 2008, according to The Freedonia Group Inc., a forecasting company based in Cleveland. The value of worldwide sales of advanced glass and ceramics reached $11.1 billion in 2005, up 12 percent from the previous year. These trends are expected to continue, with sales projected to grow by 7.3 percent each year by 2010 to a total of $17.6 billion, according to BCC Research, which produces reports, market forecasts and industry analyses for advanced materials and other sectors.
Growth in some applications for advanced ceramics has been tempered by a major obstacle: the high cost of creating ceramic parts. Expenses associated with conventional methods that use diamond tools to grind ceramics sometimes amount to more than 75 percent of a part's total cost, Shin said.
Industrial funding sources are considering the new concept for possible future manufacturing applications. The technique is potentially practical for industry because it does not require expensive "clean room" environments.
Rolls-Royce Corp. is evaluating the machining method for potential medium- and long-range applications, said W. Parker Sykes, the company's chief consultant for advanced manufacturing.
A major challenge would be learning how to integrate the technique into manufacturing operations and solving practical problems, such as how to build, operate and maintain the equipment cost effectively, Sykes said.
Purdue's Office of Technology Commercialization has filed patents in connection with the laser-deposition-machining technique, which is available for licensing.
The center is affiliated with Purdue's Center for Advanced Manufacturing and has been supported by the National Science Foundation, U.S. Army and Navy, NASA, and the Indiana 21st Century Research and Technology Fund. The research also has been funded by industrial partners, including Caterpillar Inc., Rolls Royce, International Truck and Engine Corp., Cummins Engine Co., Smiths Aerospace, Schlumberger Ltd. and DaimlerChrysler Co. LLC.