Purdue develops deposition/machining method for complex internal features

Modern Machine Shop, Sept, 2007 by Matthew D. Danford

While laser deposition is often used to create complex parts such as jet turbine components and next-generation computer memory devices, the technique cannot be used to create accurate internal features and is mostly limited to metal parts. That's because the part is machined after it is completely formed. However, researchers at Purdue University say they have created a method that not only overcomes these barriers, but is also faster and more cost-effective than traditional laser-deposition techniques.

Their technique involves depositing layers of powdered materials, melting the powder with a laser and then immediately machining each layer. Because this approach enables parts to be formed one layer at a time, it promises new industrial applications for manufacturing parts containing myriad internal features, says Yung Shin, a professor of mechanical engineering and director of Purdue's Center for Laser-Based Machining. In addition, the new method can be used to create 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.

"For example, if you are making a pump, you may have a lot of internal channels and components made of different materials," Mr. Shin says. "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."

In addition. Mr. Shin says adding the machining step makes the procedure about 20 times more accurate than basic laser deposition. It could save money, too. By providing a practical way to economically machine brittle ceramic materials, the technique could be used to manufacture parts that are not produced in large enough quantities to justify the expense of designing costly dies. The process could also enable faster production of small part quantities than is currently possible.

"From start to finish, beginning with just a design, we can have the job completed in a couple of days," Mr. Shin says. This represents a substantial time savings compared with conventional manufacturing operations, which can often take several weeks to produce similar parts.

For more information from Purdue University, visit www.purdue.edu.

Editor: Matthew D. Danford

mdanford@mmsonline.com