Why is Flatness Necessary in Geometrical Alignment? Detail Guide
Flatness is a state of being in which all elements are located in one place. Flatness tolerance specifies a tolerance zone in which the specified surface must lie and is defined by two parallel planes. Flatness is applied by a tool to an individual surface; the flatness tolerance does not require any relationship to a datum. A feature control frame has a leader or extension line attached to it.
When a feature control block with a flatness tolerance value is applied with a size parameter, the flatness tolerance value applies to the median plane of a non-cylindric surface. The derived median plane consists of the midpoint of each local size. The median plane isn’t necessarily flat.
The flatness tolerance controls the shape of the derived median plane, which is used for smoothing out the surface of the mesh. You can use the straightness tolerance to control the form of your derived line.
Why is Flatness Necessary?
Flatness controls the waviness or variations in the surface without putting tight constraints on the surface. We use flatness when we need good mating between two surfaces, but the orientation isn’t so critical. Sometimes, designers use a flatness callout to indicate that the entire surface has been worn equally.
Measurement of flatness/twist on rectangular planes
First, the laser is roughly aligned along and crosswise with the measurement object. The detector is then placed on the selected measuring points, and the values are registered.
According to the measurement method, three of the measuring point values are set to zero, while the others are recalculated for the new reference plane.
The measurement values at other measurement points will show deviations from the laser plane.
Measurement of flatness/twist on circular planes
The measurement of flatnesses/twists on circular surfaces such as flanges is based on the use of 3 reference points, situated at 120° intervals around the circle. Determine the number of measurement points for the laser plane and which will be the base points on which the laser will rest.
All measurements displayed are now relative to our laser alignment system which has measurement systems specially designed to check the flatness of flange surfaces for wind turbine towers. The software included assists you with advanced best-fits calculations.
Flatness measurement with a reference plane parallel to the horizontal plane
The laser beam is automatically adjusted according to the vial on the laser transmitter, so the measurement value at the initial measurement point is set to 0. The measurement values at other measurement points will show deviations from the horizontal plane.