⊥ Lay perpendicular to view
Lay perpendicular to view · Estado superficial · ISO 1101 + ASME Y14.5
Example in plan
How to interpret it
On the drawing, “Ra 0.8 with lay ⊥” states a lay perpendicular to view requirement.
What controls
Lay symbol requiring the machining marks to run perpendicular to the line representing the surface in the view where the callout appears. As with the other lay callouts, the reference is the drawing view. Functionally it is the opposite of the parallel case: the lay crosses the direction that previously had a continuous path, which on static seals usually hinders leakage and on sliding surfaces completely changes the behavior of the lubricant.
How to verify
Visual check under grazing light against the drawing view. Roughness is measured with the stylus traversing perpendicular to the lay, which in this case means traversing along the direction of the surface line in that view: it is easy to get this wrong and measure along the marks, so check the lay direction before setting down the roughness tester.
Common mistakes when interpreting it
- Getting the perpendicular direction wrong by taking the part, rather than the drawing view, as the reference.
- Measuring roughness in the wrong direction and getting values that do not represent the surface.
- Touching up the surface with an operation that leaves marks in another direction.
How to get it in the workshop / if it comes out of tolerance
It is obtained by orienting the machining passes at 90° to the parallel case, which sometimes means changing the fixturing or the strategy rather than the tool. It is a common callout on surfaces with transverse sliding, because marks perpendicular to the motion retain oil better. Plan tool entries so they do not leave a longitudinal mark that breaks the pattern.
Wrong direction: it is a matter of strategy and fixturing orientation, not cutting parameters. If marks in two directions coexist, the pattern is no longer perpendicular but crossed, and that is a different callout. If the roughness value fails, apply the usual finishing corrections without changing the direction of the passes.
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