Geometrical product specifications (GPS) - Dimensional tolerancing - Part 1 : linear sizes
ISO 14405-1:2016 establishes the default specification operator (see ISO 17450‑2) for linear size and defines a number of special specification operators for linear size for features of size, e.g. "cylinder", "sphere", "torus,"[1], "circle", "two parallel opposite planes", or "two parallel opposite straight lines".
It also defines the specification modifiers and the drawing indications for these linear sizes.
It covers the following linear sizes:
a) local size:
- two-point size;
- spherical size;
- section size;
- portion size;
b) global size:
- direct global linear size:
- least-squares size;
- maximum inscribed size;
- minimum circumscribed size;
- minimax size;
- indirect global linear size;
c) calculated size:
- circumference diameter;
- area diameter;
- volume diameter;
d) rank-order size:
- maximum size;
- minimum size;
- average size;
- median size;
- mid-range size;
- range of sizes;
- standard deviation of sizes.
ISO 14405-1:2016 defines tolerances of linear sizes for the following:
- a + and/or − limit deviation (e.g. 0/−0,019);
- an upper limit of size (ULS) and/or lower limit of size (LLS) (e.g. 15,2 max., 12 min., or 30,2/30,181);
- an ISO tolerance class code in accordance with ISO 286‑1 (e.g. 10 h6);
with or without modifiers.
ISO 14405-1:2016 provides a set of tools to express several types of size characteristic. It does not present any information on the relationship between a function or a use and a size characteristic.
[1] A torus is a feature of size when its directrix diameter is fixed.
