Cutting Tool Engineering
February 2009 / Volume 61 / Issue 2

Machining problems? Try universities

By George Weimer

Got a machining problem? Who doesn’t? But who do you call? Certainly your machinery or tool supplier, but you might also consider contacting a university-based manufacturing research center. Not all universities, however, have machine tool and manufacturing research centers. Actually, a limited number exist.

“It depends primarily on the expertise and interests of the existing faculty,” said Tony L. Schmitz, associate professor in the Department of Mechanical and Aerospatial Engineering and Director of the Machine Tool Research Center, University of Florida at Gainesville.

Each such research center focuses on different areas of manufacturing and machine tool technologies. At the University of Florida, for example, there are three primary research issues.

First, Schmitz and his colleagues concentrate on predicting the dynamic response of the machining system. “Through our research, we’ve developed a method called ‘receptance coupling substructure analysis’ that couples models of the tool and toolholder to a measurement of the spindle and machine,” he said.

Second, they use this information to make predictions of the process behavior in terms of stable vs. unstable cutting and part accuracy due to forced vibrations.

Finally, they organize this prediction data into a user-friendly stability lobe diagram. The goal is to identify stable zones that also meet accuracy requirements.

“I see our research efforts as decreasing the time from drawing to part by improving the manufacturer’s ability to select optimal machining parameters at the process planning stage,” Schmitz said. “A preferred implementation approach for the future is to make predictive technology available via the Internet so it can be easily accessed.”

The overall thrust of the department’s research efforts is aimed at “an improved understanding of the machining process to enable machinists to select operating parameters for decreased machining cost,” he said. “For example, by selecting an axial DOC and spindle speed combination that avoids chatter without the need for test cuts, production time can be reduced.”

Another university conducting manufacturing research is the University of California at Davis. Researchers at the school’s Mechatronics Laboratory, for example, have proposed a compact, hybrid spindle that would be multipurpose and greatly reduce setup time.

Some universities are not as well known but also do excellent industrial research, which is available to interested companies. For example, the University of North Carolina at Charlotte’s Department of Mechanical Engineering is known for its work in machine tool structural dynamics and the chip forming process.

Nearly all universities have mechanical engineering departments, whether they do research or not. “In general,” said Schmitz, “a call from a shop owner would be welcomed. Shop owners need to understand, however, that professors are basically small-business owners, just like them. We are responsible for finding the funding for our students and equipment, as well as our summer support. Research faculties are employed in 9-month contacts, and we must find our own summer salary. We do this through contracts and grants.”

The following are examples of how the University of Florida group helped manufacturers that called for advice and assistance. “I have worked with a tool manufacturer to better understand the influence of nonproportional teeth spacing on milling stability,” Schmitz noted. “For another company, we developed in-process sensing for dimensional variations of forgings that required subsequent turning. We also measured fixture and spindle dynamics for a large part machining operation that was experiencing chatter.” For another operation, they modeled the influence of machine tool error motions for on-machine probing of part dimensions.

Companies should not feel that a call to a university’s mechanical engineering department will turn into free research. “If there is a willingness to fund a research effort at some point, then initial discussions can be very fruitful,” Schmitz said. “If there is an expectation that the ‘state university is there to solve my problems because I support it with my tax dollars,’ then the collaboration won’t get very far.” Some professors, he added, do independent consulting.

The point is that university-based machining and other manufacturing research efforts are focused on the machine tools and manufacturing systems end users currently operate or will in the future. Contacting and developing relationships with them can lead to impressive mutual benefits. CTE

About the Author: George Weimer, a freelance writer based in Lakewood, Ohio, has an extensive background in the metalworking industry’s business press. Contact him by e-mail at gweimer@jwr.com.



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