Surface Roughness 247
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d:\N-Design\Des16-1.pm5
If it is necessary to indicate the sampling length, it should be selected from the series
given in ISO/R 468 and be stated adjacent to the symbol, as shown in Fig. 16.4d. If it is necessary
to control the direction of lay, it is specified by a symbol added to the surface roughness symbol,
as shown in Fig. 16.4e.
NOTE The direction of lay is the direction of the predominant surface pattern, ordinar-
ily determined by the production method employed.
Table 16.3 shows the symbols which specify the common directions of lay.
Table 16.3 Symbols specifying the directions of lay
Symbol Interpretation
Parallel to the plane of projection
of the view in which the symbol is
used
Perpendicular to the plane of
projection of the view in which the
symbol is used
Crossed in two slant directions
relative to the plane of projection
of the view in which the symbol is
used
Multi-directional
Approximately circular, relative to
the centre of the surface to which
the symbol is applied
Approximately radial, relative to
the centre of the surface to which
the symbol is applied
M
C
R
= ^ X M C R
Direction of
lay
T
Direction of
lay
X
Direction of
lay