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[Sandia Lab News]

Vol. 53, No. 9        May 4, 2001
[Sandia National Laboratories]

Albuquerque, New Mexico 87185-0165    ||   Livermore, California 94550-0969
Tonopah, Nevada; Nevada Test Site; Amarillo, Texas

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Sandia, industry develop chatter suppression unit MicroChemLab breakthroughs lead to commercialization International arms control conference


Sandia helps design chatter-suppression device that would allow US factories to mill metal faster

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By John German

Machinists dread "chatter," the violent vibration of a milling machine's rotating tool bit against the piece of metal being milled.

Chatter can destroy a cutting tool or spoil a surface. If the work piece is a precision-machined part such as an aircraft engine, the damage can be unacceptably costly.

More often though, operators of today's high capacity milling machines avoid chatter altogether by running their machines at conservatively slow tool speeds and shallow cuts.

Now Sandia -- working with an industrial group including Lockheed Martin, Intelligent Automation Inc. (IAI), Ingersoll Milling Machine Co., and Active Signal Technology (AST) -- has tackled the industrial-age-old problem of milling machine chatter in a 21st century way.

As the tool turns

Using the latest in computational structural dynamics modeling and "smart structures" capabilities, Sandia examined mathematically how chatter happens, then helped the consortium design a vibration control system that actively suppresses chatter as the tool spins at thousands of rpm. ("Smart structures" refers to the use of sensors, actuators, computers, and control algorithms to produce a response in a structure that makes that structure more effective.)

In a demonstration earlier this month in Rockford, Ill., using Ingersoll's developmental horizontal-axis hexapod milling machine, the new Smart Spindle Unit (SSU) allowed the machine to cut deeper and faster, removing metal at more than five times its original rate.

Its developers say the SSU could enable machinists to operate their machines closer to their design capacities, possibly shaving minutes or hours off the milling of each metal part and dollars off production costs.

"It could expand the envelope of stable cutting into faster and deeper regimes with the same precision," says Terry Hinnerichs (9126), Sandia SSU project leader. "It might drive down the cost of metal removal significantly."

The work was funded by the Defense Advanced Research Projects Agency and led by Lockheed Martin. It began in 1994 as part of a national campaign to bolster the competitiveness of US factories by improving manufacturing technology.

The Sandia project, directed by David Martinez, Manager of Structural Dynamics Development and Smart Structures Dept. 9124, was one of several manufacturing-related smart structures and materials efforts in the mid 1990s by researchers from Dept. 9124 and the Smart Structures Lab in Structural Dynamics Engineering Dept. 9125, managed by Tom Baca.

How it works

Just like the bone-jarring bounce that occurs when your car's tires roll too fast over a washboard road, chatter happens when a milling machine's cutting tool bounces off grooves on the metal's surface left there by the previous cut. Choking back the spindle speed lessens the vibration, just like slowing down your car does.

The SSU essentially is a smart suspension system for the machine's rotating parts.

Strain gauges mounted to the cutting tool sense bending strains on the tool. These measurements are radioed via a specially designed telemetry system to the SSU's control processor, which maps the strains into a non-rotating coordinate system and then generates command signals that are sent to four actuators placed around the spindle.

These electrical signals cause electrostrictive ceramic materials inside each of the actuators to expand by just a few microns, instantaneously nudging the cartridge holding the spindle in the direction needed to correct the vibration.

The SSU can update forces on the spindle 16,000 times per second. At 3,600 rpm, that's 266 corrections per revolution, more than enough to correct typical chatter vibrations, says Jim Lauffer (8727), who helped design the unique telemetry system necessary to "fly" sensor data off the rotating spindle and a control system to filter out transmission signals while minimizing the time delay.

"You can hear the machine squeal from the chatter," says Jeff Dohner (1749). "Then when you turn the SSU on, the chatter is silenced."

Now that a developmental SSU has been demonstrated, says Terry, the developers hope to find a manufacturer willing to adapt it for more universal applications.

"The performance characterizations suggest the SSU approach would be particularly useful for milling hard-to-machine materials such as high-strength steels, titanium, and nickel-based superalloys, or for machining deep pockets in molds and dies," says Terry.

"The digital world allows you to design an intelligent machine that wouldn't have been possible a decade ago," says Jeff. "I think we can apply today's technologies to a lot of manufacturing processes to make them better and more economical."

"The idea that you could not just prevent, but in real-time recover from, instability on a milling machine is something not too many people believed we could do," adds Jim. "Here with the economy down, it would really help some US companies if we could put this into a commercial product. I think others will look at this effort and say it's a significant achievement."

Sandia conducted the detailed computational modeling (coupling cutting forces and structural dynamics), controls analysis, hardware development and implementation, and experimental characterization of the SSU's performance on and off the milling machine.

Lockheed Martin and AST developed the actuators. IAI developed the controls hardware. Ingersoll provided the hexapod milling machine platform.

Labs SSU team members include Terry, Jeff, Jim, Dave Kelton (9125), and Brian Driessen (9124). -- John German

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MicroChemLab advances lead to first commercialization partnership

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By Nancy Garcia

Breakthroughs that were hardly more than a glimmer in the eye five years ago have led to the first commercialization agreement to stem from the ÁChemLab project.

This effort to miniaturize chemical analysis in a hand-held device resulted in demonstration of the first chip-based system to analyze liquids through microscale high-pressure liquid chromatography. Drawn to this success, a world leader in analytical instrumentation, Waters Corp. of Milford, Mass., announced in March that the company is licensing Sandia's microfluidics technology and launching a cooperative research and development agreement to further develop this expertise.

Says Duane Linder (8101), who oversees research efforts to shrink liquid analysis into a chip-based system, "Sandia was the first, and only, organization to demonstrate a chip-based version of high-performance liquid chromatography, which is the most widely used method for chemical analysis of liquids in the world."

The work was initially begun in late 1996 through a Grand Challenge Laboratory-Directed Research and Development project. Based on advancements made since then, a refined unit for detection of chemical and biological agents is being developed. The research involves some 40 Sandians across the Labs, with gas-phase analytical research centered in New Mexico and liquid-phase research centered in California. Primary support of that work comes from DOE's Chemical and Biological National Security Program (which started a five-year program in 1999) and relatively new funding from the Department of Defense's Defense Threat Reduction Agency. The focus, Duane says, is to develop units that can be used by emergency responders or soldiers to detect chemical or biological agents in the field, so they may don protective gear.

Since the initial research began, he says, its broad potential applicability has been recognized. Researchers believe a hand-held device might sniff out explosives, signal food quality, and check environmental safety for paramedics, fire fighters, law enforcement officers, and other specialists who respond to emergencies in which chemical or biological hazards are suspected. Devices could also be tailored to detect pollutants near their source, perform medical diagnostics at a bedside, screen new pharmaceutical drug candidates, or optimize industrial processing.

"We are really strong in certain aspects of microfluidics," Duane says. Sandia researchers have demonstrated the ability to generate more than 9,000 pounds per square inch of pressure in liquids that are moved under an electric current through channels thinner than a human hair. The team has also shown flow rates of more than 100 microliters per minute. Potential applications include microscale pumps, valves, and actuators, as well as cooling for microprocessors.

Waters envisions coupling miniaturized chromatography systems with its mass spectrometry analytical products, Waters' senior vice president of R&D, John Nelson, said in announcing the licensing and partnership agreement.

"This is a major step forward in our vision to provide miniature chemical analysis systems for national security needs ranging from the detection of chemical and biological agents to the cleanup and monitoring of environmental waste sites," added John Vitko, Director of Exploratory Systems and Technology Center 8100. -- Nancy Garcia

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International Arms Control Conference brings 300 to NM to talk world peace

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By John German

When you gather into one room 300 people with titles like ambassador, general, commander, director, and senior analyst representing nations such as Russia, Kazakhstan, China, South Korea, Pakistan, India, Israel, South Africa, and France, you can expect a weighty discussion of topics that influence the world's ability to get along.

Such was the case last weekend at the 11th International Arms Control Conference in Albuquerque, sponsored by National Security Programs Div. 5000, where you could hardly throw a sweet roll without hitting someone with an embassy for an address, including 15 participating ambassadors.

Five panel discussions explored issues such as offensive versus defensive military postures, cooperative US-Russia threat-reduction efforts, biological weapons proliferation, North Korea's nuclear ambitions, and homeland defense.

In an opening address, Amb. Abdallah Baali, Permanent Representative of Algeria to the United Nations, described successes at the 2000 Nonproliferation Treaty (NPT) Conference, interpreting the new agreements reached there as having "underscored the unequivocal undertaking by the nuclear weapon states to accomplish the total elimination of nuclear weapons -- a task no longer described as just an 'ultimate goal.' "

Ballistic missile defense

Amb. David Smith of Global Horizons, Inc. spoke in favor of US proposals to develop a national missile defense system. "America should consult its allies, explain its missile defense plans, act transparently, and cooperate with any interested country," he said. "But our view of the ballistic missile threat to our country, our role in the world, and our consequent defensive response are not matters for debate . . . It is time to move from a strategy based on nuclear destruction to a more balanced strategy that includes defenses, which, after all, harm only attacking missiles."

Guillaume Parmentier of the French Center on the United States countered, calling for a more balanced approach to deterring and responding to aggression. "The geopolitical conditions of European countries, coupled with historical memories [of failures to contain aggression based on a defensive posture], create widespread skepticism of American plans in this respect. The illusion of vulnerability could create much misperception and be the cause for disastrous decisions. . . . Defense is seen in Europe as a supplement to offense and diplomacy. It is not and cannot be a substitute."

Jack Mendelsohn of the Lawyers Alliance for World Security warned of the potentially destabilizing effects on US-Russia-China relations if a US ballistic missile defense is developed. "Any national ballistic missile defense system that threatens the ability to retaliate will, in turn, stimulate a response to ensure that offensive forces retain the capability to deter."

In a keynote address, Amb. Wolfgang Hoffman, Executive Secretary of the Comprehensive Test Ban Treaty Organization, discussed ongoing measures to support the treaty. More than 250 people from 70 countries are working to develop an international monitoring system capable of detecting clandestine nuclear tests forbidden under the treaty, he said. The system should be operational by 2005.

Brig. Gen. Thomas Kuenning (ret.), Director of the Cooperative Threat Reduction (CTR) program, detailed the "remarkable" achievements in US- Russian efforts to retreat from their Cold War defense postures. So far more than 5,000 warheads, 600 ballistic missiles, 360 silos, and 330 launchers have been eliminated through CTR programs, he said.

Victor Mizin, Russian Diplomat-in-Residence at the Monterey Institute of International Studies, cautioned against proposed US cutbacks in funding for CTR projects, which, he said, have from a purely pragmatic viewpoint "reduced the number of warheads and launchers aimed at the US" and reduced the "danger of the massive proliferation from the ex-USSR territory."

However, he said, Russian leaders sometimes take the cash flow for granted, and many Russian people misinterpret the program as US meddling in Russian security issues. "Russian officials . . . will do nothing if . . . lavish financial support is not assured," he warned.

In a session on North Korea's nuclear ambitions, Piet de Klerk, Director of Policy Coordination at the International Atomic Energy Agency (IAEA), said that at no point has the IAEA been able to conclude that North Korea has complied with its obligations under the Nonproliferation Treaty.

Gary Samore of the US Department of State said the Bush administration is in a Catch 22 regarding North Korea's nuclear program. "On one hand," he said, "a strategy intended to undermine and ultimately replace the North Korean regime in order to eliminate its nuclear and missile programs would accelerate these programs in the near term and increase the danger of conflict on the peninsula . . . On the other hand, a strategy of carrot-and-stick engagement, which provides assistance and improved bilateral relations to North Korea in exchange for restraints on its nuclear and missile programs, helps prop up the regime with no guarantee that it will ever give up those capabilities in the end."

Seoksoo Lee (South Korea) of the National Defense University added: "It should be reminded that peace be created both by peaceful means and non-peaceful means. In order to cope with Pyongyang's military adventurism, it is necessary but not sufficient to adopt diplomacy for nonproliferation. If diplomacy is not working, containment becomes the norm."

In a session on homeland defense, Amy Smithson of the Henry L. Stimson Center questioned the effectiveness of programs to respond to a mass-casualty terrorist attack on US soil. "In the years ahead, domestic preparedness must put as much emphasis on public health and hospital preparedness as on disaster-scene rescue capabilities," she said. "A sign of maturity in the program will be its transformation from an inside-the-beltway justification for a spending carnival to preparedness standards and capabilities that are institutionalized and sustained over the long term. . . . Bluntly put, an absurdly small slice of the funding pie has made it beyond the beltway."

Conference chair James Brown (5325) says, "This was a very successful two-day symposium that provided the venue that permitted the leaders of the arms control and nonproliferation communities to come together in an environment that allows the free ranging exchange of ideas. This in turn enhances the opportunities for better understandings and establishes valuable relationships among these national security and foreign affairs experts." -- Chris Burroughs

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Last modified: May 7, 2001


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