Form and position tolerances iaw. ISO 1101 and Japanese standard JIS B 0001: The most important information

Toleranzen DIN, EN, ISO, JIS

DIN ISO 1101 and JIS B 0001 are standards that enable design engineers to ensure accurate component fit. These standards are part of the Geometrical Product Specification (GPS).

What are form and position tolerances?

Form and position tolerances are technical specifications that ensure uniform handling of dimensions and tolerances in manufacturing. They are mainly used in the manufacture of components in order to ensure the accuracy of parts.

There are various properties that influence the fit accuracy of components, such as:

the surface finish
the size
the thickness
the position and the contour

DIN ISO 1101 form and position tolerances distinguish between two different types of tolerances: error tolerance and position tolerance. Together, these two tolerances represent the most important factors to ensure accurate component fit.

The error tolerance indicates the permissible deviations in the dimensions and shape of the components.
The position tolerance indicates the permissible deviations of the position of the components.

How are form and position tolerances used?

When specifying form and position tolerances, it is important to take into account the manufacturing processes, materials and environmental conditions. The dimensions must be selected such that they correspond to the manufacturing technology and the desired fit result can be achieved. For this purpose, the user must know the requirements of the respective component and the manufacturing process.

Selecting the right material is also important to ensure reliable fit. The choice of material depends on the technical requirements and the environment in which the component is used.

Which symbols are used in the technical drawing iaw. ISO 1101?

Symbols for form

Symbols and their definitions
Designation	Symbol	Definition
Straightness		For areas: The tolerated line must in each plane lie between two parallel lines with a distance of t. Note: The straightness on surfaces is measured in the direction of the line in the indicated view. Surfaces can be straight in the X-axis even if they are curved along the Y-axis. For axes: The tolerated axis must be in a cylinder (⌀ = t).
Flatness		The tolerated area must lie between two parallel planes (distance t).
Roundness		The tolerated circumferential line must in all sectional planes lie perpendicular to the central axis between two concentric circles (Δr = t).
Cylindricality		The tolerated outer surface must lie between two coaxial cylinders (Δr = t).
Profile of a line		The tolerated profile must in each plane lie between two equidistant envelope lines, the distance of which is defined by circles (⌀ = t).
Profiles of a surface		The tolerated area must lie between two equidistant envelope surfaces, the distance of which is defined by spheres (⌀ = t). Note: The center point of the circle or sphere is on the ideal line or area.

Symbols for direction

Symbols and their definitions
Designation	Symbol	Definition
Parallelity		For areas: The tolerated area must lie between two planes (distance t) that are parallel to the reference. For axes: The tolerated axis must be in a cylinder (⌀ = t) whose axis is parallel to the reference.
Perpendicularity		For areas: The tolerated area must lie between two planes (distance t) that are perpendicular to the reference. For axes: The tolerated cylinder axis must lie in a cylinder that is vertical to the reference area (⌀ = t).
Angularity		For areas: The tolerated area must lie between two planes (distance t) that are inclined at the specified angle in relation to the reference. For axes: The tolerated axis must lie between two parallel planes (distance t) that are inclined at the specified angle in relation to the reference.

Symbols for location

Symbols and their definitions
Designation	Symbol	Definition
Position		The center of the bore must be in a square (a = t) whose center matches the theoretically accurate position of the bore hole. Square aligned according to theoretically exact dimensions with ⌀ symbol: The center of the bore must be in a circle (⌀ = t) whose center matches the theoretically accurate position of the bore hole. ⌀ symbol before the tolerance value (see tolerance limit range (image)) The position of areas can also be defined.
Concentricity		The center point of the tolerated circle must lie in a circle (⌀ = t) whose center point is concentric in relation to the reference. The axis of the tolerated area must lie in a cylinder (⌀ = t) whose center axis is coaxial in relation to the reference. Note: Coaxiality cannot be measured if the length of a cylindrical body is too short.
Symmetry		The tolerated center plane must lie between two parallel planes (distance t) that are symmetrical in relation to the reference.

Symbols for runout

Symbols and their definitions
Designation	Symbol	Definition
Runout (radial)		For a revolution around the reference axis, the runout deviation must not exceed t.
Axial run-out (axial)		For a revolution around the reference axis, the axial runout deviation must not exceed t.
Total runout (radial)		For multiple rotations around the reference axis and simultaneous axial displacement, the runout deviation must not exceed t.
Total axial runout (axial)		For multiple rotations around the reference axis and simultaneous radial displacement, the axial deviation must not exceed t.

What influence do general tolerances and DIN ISO 2768-1 have?

General tolerances iaw. DIN ISO 2768-1 are an important factor for the perfect fit of components. They define the permissible deviations in form, dimension, position and orientation of components in a manufacturing process.

These tolerances can be used to ensure component accuracy without the need for additional measurements.

As a Japanese manufacturer, MISUMI manufactures its products iaw. JIS B0401, which is identical to DIN ISO 2768-1.

Find out more about general tolerances here.

Tolerance classes iaw. ISO 22081 and DIN ISO 2768: Optimized use of general tolerances

Tolerances are an essential aspect for manufacturing mechanically moving parts, as they ensure the correct interaction of components. General tolerances and their tolerance classes are used to simplify drawings. The standard DIN ISO 2768 specifies tolerances. Many design engineers use general tolerances as a simplified variation of tolerances to facilitate the design process.