Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Rough times: NIST's new approach to surface profiling

11.01.2008
Researchers at the National Institute of Standards and Technology (NIST) have developed a novel technique for measuring the roughness of surfaces that is casting doubt on the accuracy of current procedures. Their results announced in a forthcoming paper* could cut development costs for automakers as they design manufacturing tools for new, fuel-efficient, lightweight alloys.

Surface roughness is a key issue for auto manufacturers and other industries that use sheet metal, one that goes far beyond simple cosmetics. Faint striations and other marks that appear when metal is shaped can indicate residual stresses that can cause the part to fail later on. They also lead to extra wear and early retirement for the expensive stamping dies used to form sheet metal into fenders and other body parts (a typical production die can cost $2 million or more.)

And measures of surface roughness feed into models that predict friction and the metal’s “springback”—the amount it will unbend after being stamped. Springback has to be known and controlled to build accurate dies for complex metal shapes. A significant cost in introducing new lightweight alloys for cars is the trial-and-error process needed to develop a new set of dies for each new alloy.

Conventionally, roughness is measured with a profilometer, an instrument with a probe like a high-tech phonograph needle that is tracked in a line across the test surface to record the peaks and valleys. The process is repeated several times at intervals across the test surface, and the results are averaged into a “roughness” figure. (New non-contact instruments use optical probes, but the idea is the same.) But NIST researchers have found that these measures may be misleading—as both measurement uncertainties and statistical errors are compounded when the 2-D lines are extrapolated to the entire surface.

NIST’s approach uses data from a scanning laser confocal microscope (SLCM), an instrument that builds a point-by-point image of a surface in three dimensions. The data from a single SLCM image—representing an area of about 1000 X 800 micrometers by 20 micrometers in depth—are analyzed using mathematical techniques that treat every point in the image simultaneously to produce a roughness measure that effectively considers the entire 3-D surface rather than a collection of 2-D stripes.

One early finding is that the generally accepted linear relationship between surface roughness and material deformation is wrong, at least for the aluminum alloy the group studied. The more accurate data from the 3-D analysis shows that a more complicated relationship was masked by the large uncertainties of the linear profilometers. The NIST researchers hope their new technique will lead to more accurate models of the effects of strain on new alloys and, eventually, lower development and tooling costs for metalworking industries.

Michael Baum | EurekAlert!
Further information:
http://www.nist.gov

More articles from Materials Sciences:

nachricht Serendipity uncovers borophene's potential
23.02.2017 | Northwestern University

nachricht Switched-on DNA
20.02.2017 | Arizona State University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>