Diamonds are forever
ZEISS introduces the world´s first-ever diamond-coated measuring stylus manufactured in a series process.
Aalen, December 5, 2014 - Carl Zeiss 3D Automation GmbH (Aalen, Germany) and Dutch
Diamond Technologies BV (Cuijk, the Netherlands) have launched the world’s first-ever
diamond-coated stylus for continuous measurement on coordinate measuring machines
(CMM). The main advantage, compared with conventional ruby and silicon-nitride styli, is its
durability. The stylus delivers precise measuring results over many years, even when scanning
ultra-hard and soft materials. And compared with full-diamond sensors, the new diamondcoated
styli are considerably cheaper.
On the tip of every stylus for coordinate measuring machines is a ball, or sphere, with a diameter
between 0.12 and 12 millimeters. It glides over the surface of a work piece, collecting the coordinates
that are used to compare the actual geometry with the target values. A sphere made of ruby or siliconnitride
loses its roundness over time when it comes into contact with very hard materials, such as
ceramics, or very soft ones, such as aluminum alloys. This is because the scanning of ultra-hard work
pieces in particular can gradually wear down the spherical surface, even when low pressure is applied.
Likewise, ruby or silicon-nitride spheres can cause material to be separated from soft work pieces,
which are then deposited on the sphere and can cause it to be less round. Both these effects can lead
to inaccurate measuring results.
“We developed full-diamond measuring styli seven years ago to enable our clients to measure
precisely and in a repeatable manner over time, without having to permanently control or exchange
the measuring styli,” says Dr. Frank Richter, CEO of Carl Zeiss 3D Automation GmbH. “In order to
provide the benefits of a diamond surface to even more users, we’re now extending our portfolio with
less-expensive diamond-coated styli, which are available in various sizes.”
When working with extreme materials, an operator needs to regularly clean and frequently replace styli
made of ruby or silicon-nitride — usually once every shift. This costs time and money, because while
the styli are exchanged and the work piece recalibrated, the machine cannot be used productively.
And if the operator decides not to scan components completely using a coordinate measuring machine
— because measuring individual points would deform the stylus less fast — then either the
measurement process itself would take longer or the uncertainty of the results would increase. The
reason for this is that compared to the scanning procedure, which generates a large amount of
measurement data, single-point measurement, which is much slower, has certain disadvantages:
users face the dilemma of either collecting fewer measurement points in order to achieve a higher
throughput (thereby accepting higher measuring uncertainty) or measuring many single points, which
reduces the uncertainty of measurement, while at the same time increasing the measurement time.
With the new styli developed by ZEISS and Dutch Diamond Technologies, which go by the brand
name Diamond!Scan, it is no longer necessary to control and clean the styli because materials cannot
stick to their surface. And since the styli retain their original form over many years, they do not need to
be replaced. Furthermore, since scanning work pieces no longer negatively impacts the precision of
the measuring results, there is no need to collect individual measuring points. As a result, the
throughput of the coordinate measuring machine increases. And since there is no material build-up on
the diamond surface, the diamond-coated styli can also be used for scanning aluminum. Unlike fulldiamond
styli, diamond-coated styli are not only cheaper; they also have a higher circularity of under
150 nm, which makes them more precise. Despite these benefits, full-diamond styli are still best suited
for hard materials such as ceramics.
In contrast to full-diamond styli, in which the entire sphere is made of the mineral, diamond-coated styli
have a ceramic ball whose surface is coated with diamond. Diamond-coated styli are also less
expensive than the full-diamond kind due to lower material costs and because it is not necessary to
individually hone the sphere. The Diamond!Scan diamond-coated styli are currently available in 2.1
and 5 mm diameters. Other sizes will be available soon. All Diamond!Scan styli can be ordered
through the online shop: www.probes.zeiss.com
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