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DPM Marking Technologies |
Two-dimensional (2D) codes have been selected for DPM
Identification applications due to advantage in their small size,
error correction, and amount of data that can be stored as compared
to 1D codes. The Data Matrix 2D symbology has emerged as the standard
code type for parts tracking. These Data Matrix codes are marked on
the part using several methods.
Common methods include dot peening, laser
etching, electro-chem etch, and ink
jet marking.
The marking method used is typically defined by engineering and takes
into consideration acceptable marking methods for a particular part
and/or material, the life expectancy of the part, material composition,
environmental wear and tear, surface texture, the amount of space
allotted for a code, and the amount of data to be encoded on each
part.
While the marking method used has some bearing on DPM reader performance,
it plays an even more important role in DPM verification. Unlike reading,
a verifier must provide an optimal image in order to provide meaningful
results. The lighting must be of consistent intensity, direction and
uniform throughout the field of view. The marking method and material
will dictate what lighting method to use.
For example, in laser-etch marking techniques, the quality of a mark
is directly affected by how the laser interacts with the surface material
of the part being marked. In order to determine how well the laser
marked the part, a diffuse bright field light may provide the best
image. In dot peen marking applications, the indentations can impact
quality by causing an uneven distribution of light and dark pixels
when an image of the code is formed. In this case, a low angle light
will likely provide the optimal image to determine mark quality.
Finally, no matter what marking method is used, the goal is to produce
a mark that is readable throughout the entire lifecycle of a part
to achieve full traceability. Part lifecycle requirements vary from
industry to industry. For example, the aerospace industry might expect
a 25-year lifecycle for parts, whereas the automotive industry may
expect parts to have a ten-year lifecycle.
Marking Methods
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© Copyright 2006 Acrovision Ltd |
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