Table of Contents
What is flatness and roughness?
Flatness is the ratio of the measure of the surface divided by its projection, and roughness the average of the square of the mean curvature of the surface per unit area.
How do you describe flatness?
Flatness may be defined in terms of least squares fit to a plane (“statistical flatness”), worst-case or overall flatness (the distance between the two closest parallel planes within).
What do you mean by flatness?
Flatness definition The state of being flat. noun. The state of being two-dimensional; planar : planarity. noun. Mattness, the quality of a painted surface which scatters or absorbs the light falling on it, so as to be substantially free from gloss or sheen.
What is flatness in drawing?
Flatness is a measure of a surface’s form compared against itself, indicating that all the points along the surface lie in the same plane. Symbolized in GD by a parallelogram, flatness allows you to limit waviness or variation in a surface without tightening its dimensional tolerance.
What flatness means?
flatness noun [U] (LEVEL QUALITY) the quality of being level and without curved, high, or hollow parts: The flatness of the desert was broken only by a few large piles of rocks. SMART Vocabulary: related words and phrases. Straight, even and level. be (as) flat as a pancake idiom.
How is flatness defined?
What is a normal flatness tolerance?
A flatness control is applied to the top surface. We know that the flatness applies to the surface because the flatness control points to the top surface. The flatness tolerance zone is two parallel planes 0.1 mm apart. The size can never be greater than 31 or less than 29.
What are the units of flatness?
I-Units is an exacting quantitative flatness measurement. It is a dimensionless number that incorporates both the height (H) and peak to peak length (L, or P in the diagram below) of a repeating wave. For example: a sheet with a 1/16” high wave which repeats every 12” would have an I-Unit value of 6.7.
Where is flatness used?
Usually, flatness is used to give a surface an even amount of wear or for sealing properly with a mating part. Commonly used on a fixture that must mate flush with another part without wobbling, but where orientation is not important.
How do you get flatness?
To achieve a critical flatness characteristic, most die designers try to keep the part flat during the cutting operation, using methods such as pressure blanking, compound blanking, and cut and carry, as well as specialty stamping operations like fineblanking and Grip Flow®.
How is GD flatness calculated?
Place the target on the precision plane table and secure it in place. Set the dial gauge so that its measuring part comes into contact with the measurement surface. Move the target so that the measurement surface is evenly measured, and read the dial gauge values. The largest deviation value is the flatness.
What is flatness in GD?
Flatness is a GD form tolerance that is conceptually simple. According to the ASME Y14.5 standard, it “specifies a tolerance zone defined by two parallel planes within which the surface must lie.” Figure 1. ASME GD Flatness Example
What is the meaning of flatness in geometry?
Definition of Flatness. The GD Flatness symbol references how flat a surface is. It is not dependent on any other datums or features. Flatness is a form control, because it is used to control the form or shape of a feature. It controls how much a surface on a part may deviate from an ideal plane.
What is the flatness tolerance of a surface?
The flatness tolerance references two parallel planes (parallel to the surface that it is called out on) that define a zone where the entire reference surface must lie. Flatness tolerance is always less than the dimensional tolerance associated with it.
Is flatness dependent on any datum or feature?
It is not dependent on any other datums or features. Flatness is a form control, because it is used to control the form or shape of a feature. It controls how much a surface on a part may deviate from an ideal plane.