Scanning is a term that is widely used with CMMs to mean three different types of
measurement. Each type of measurement has both positive and negative effects on the
measurement process these three basic types are.
Digital or peck scanning: Which is taking individual points in close proximity along a line or a
cross a surface or other geometric feature to define the feature. Spacing of the points are
determined by the operator/programmer dependent on the feature being measured, It is
inexpensive and does typically not require additional hardware with the CMM and is good for
simpler applications or those features that do not require a lot of definition. It is not a good way
to do form measurement if tight tolerances are required or if there are rapid changes in the
surface or form to be measured
Analog scanning or continuous contact scanning: Is the process where a stylus is in
continuous contact with the surface of the item to be measured, this provides greater accuracy
typically and allows for more data points. Faster than digital scanning in most cases and
provides greater point density. Programmers need a higher level of skill as they must consider
and apply filters to the points gathered to eliminate errors, such as outliers and friction issues
that come from the styli being in constant contact with the surface. A great number of
improvements in this technology has come forward in the past few years with
a) accuracy dependent on system speed. (the faster you move the greater the error) which
is another consideration for the operator when writing the program.
b) Revo 5 axis technology which allows scanning at up to 500mm per second and 400 data
points a second without degradation of accuracy and that with its improved technology
reduces and in some cases, or eliminates the need for applying filters to the scanned
This type of scanning is more expensive than digital scanning, but gives greater accuracy and
can provide throughput improvements on some parts up to 90%
Non-contact or Laser scanning: Is the third type of scanning being used in the market today,
it is extremely quick and gather millions of data points in seconds. This type of scanning is
great for applications with greater tolerances, (such as castings, plastics or rough machining
operations) or flexible parts where contact can deform the part and thus the measurement or
reverse engineering applications. Things that might be of issue are, parts with high reflectivity,
parts that are clear or opaque that do not reflect light well, part tolerances, (laser scanners
typically have a greater than 10-micron error in practical applications) Operator skill level
required to handle the set up and filtering of the part data, and that the device is line of site, so
that some features may not be able to be measured effectively and require additional
measurement with a contact type probe
These are rudimentary explanations of scanning with a CMM and are intended only to give a
basic understanding, if further information is needed please contact Masters Precision via email
sales@mastersprecision.com
measurement. Each type of measurement has both positive and negative effects on the
measurement process these three basic types are.
Digital or peck scanning: Which is taking individual points in close proximity along a line or a
cross a surface or other geometric feature to define the feature. Spacing of the points are
determined by the operator/programmer dependent on the feature being measured, It is
inexpensive and does typically not require additional hardware with the CMM and is good for
simpler applications or those features that do not require a lot of definition. It is not a good way
to do form measurement if tight tolerances are required or if there are rapid changes in the
surface or form to be measured
Analog scanning or continuous contact scanning: Is the process where a stylus is in
continuous contact with the surface of the item to be measured, this provides greater accuracy
typically and allows for more data points. Faster than digital scanning in most cases and
provides greater point density. Programmers need a higher level of skill as they must consider
and apply filters to the points gathered to eliminate errors, such as outliers and friction issues
that come from the styli being in constant contact with the surface. A great number of
improvements in this technology has come forward in the past few years with
a) accuracy dependent on system speed. (the faster you move the greater the error) which
is another consideration for the operator when writing the program.
b) Revo 5 axis technology which allows scanning at up to 500mm per second and 400 data
points a second without degradation of accuracy and that with its improved technology
reduces and in some cases, or eliminates the need for applying filters to the scanned
This type of scanning is more expensive than digital scanning, but gives greater accuracy and
can provide throughput improvements on some parts up to 90%
Non-contact or Laser scanning: Is the third type of scanning being used in the market today,
it is extremely quick and gather millions of data points in seconds. This type of scanning is
great for applications with greater tolerances, (such as castings, plastics or rough machining
operations) or flexible parts where contact can deform the part and thus the measurement or
reverse engineering applications. Things that might be of issue are, parts with high reflectivity,
parts that are clear or opaque that do not reflect light well, part tolerances, (laser scanners
typically have a greater than 10-micron error in practical applications) Operator skill level
required to handle the set up and filtering of the part data, and that the device is line of site, so
that some features may not be able to be measured effectively and require additional
measurement with a contact type probe
These are rudimentary explanations of scanning with a CMM and are intended only to give a
basic understanding, if further information is needed please contact Masters Precision via email
sales@mastersprecision.com
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