GE SABA Broschüre
GE Inspection Technologies
Xray
In order to obtain accurate character rec-
ognition results the following prerequisites
have to be met:
ognition results the following prerequisites
have to be met:
• The font to be used is the ISO Stan-
dard Type for drawings in accordance
with DIN 6776 B vertical. This type is
characterized by high legibility.
with DIN 6776 B vertical. This type is
characterized by high legibility.
• Each individual numeric character
must be distinct in shape to prevent
confusion with others.
confusion with others.
• The distance between two numeric
characters must be three times the
line width (d).
line width (d).
• The numeric character height (h)
must be at least 10 mm (see
Figure 1).
Figure 1).
• For serial inspection the numeric
characters in the image must always
appear in the same place.
appear in the same place.
• The arrangement of the numeric char-
acters in the image must be rectangu-
lar. A diagonal arrangement prevents
them from being recognized.
lar. A diagonal arrangement prevents
them from being recognized.
• The type must be highly contrastive.
The proportion of the type elevation
T1 to the material thickness T2 (see
Figure 2) must be constant through-
out the entire numeric character area
(see Figure 3) and be at least 1:10
given a numeric character height of
10 mm.
T1 to the material thickness T2 (see
Figure 2) must be constant through-
out the entire numeric character area
(see Figure 3) and be at least 1:10
given a numeric character height of
10 mm.
Example:
Given a 10 mm material thickness the
type elevation must be 1 mm (-0.2
mm, +0.8 mm).
type elevation must be 1 mm (-0.2
mm, +0.8 mm).
• No further structures (e.g. cooling
fins) must be in the numeric character
area as they will affect results.
area as they will affect results.
• In the numeric character area the
material thickness must be constant.
• As the type elevation is limited for
reasons inherent in the casting pro-
cess, the numeric characters should
be placed in workpiece areas with the
least possible material thickness. This
is the only way to ensure a sufficiently
high contrast in the X-ray radioscopic
image.
cess, the numeric characters should
be placed in workpiece areas with the
least possible material thickness. This
is the only way to ensure a sufficiently
high contrast in the X-ray radioscopic
image.
Description
Figure 1 - Dimensions for 10 mm numeric character size
Figure 2 - Proportion T1/T2
Figure 3 - Numeric character area
The following points are important for X-ray character recognition on wheels:
• The strip must not contain any other information
except for the numeric characters.
• For all wheels of one type the strip must have the
same height position.
• The number of numeric characters (3 in the example
on the right) must be the same for all wheel types to
be inspected in one plant.
be inspected in one plant.