The basis for precise manufacturing
Form and location tolerances have a decisive impact on the quality and the functionality of products because they help optimise manufacturing processes and guarantee the interchangeability of components. Through the precise definition of form and location tolerances, you can ensure that your products meet high requirements and standards. The definition of these tolerances further guarantees precise manufacturing and optimum component functionality.
Symbols for a perfect fit
Form and location tolerances are more than just symbols in a drawing, they are key to the functionality and interchangeability of components. Each symbol stands for a specific tolerance type and indicates the permitted deviation.
- Straightness: indicates the degree to which a line must be straight
- Flatness: indicates the degree to which a surface must be flat
- Roundness: indicates the degree to which a circle or cylinder must be round
- Cylindricity: indicates the degree to which a solid must be cylindrical
- Position: indicates the position of an element with reference to another element
- Direction: indicates the orientation or direction of an element
Form and location tolerances FAQs
What are form and location tolerances?
To ensure a component has the required functions, it can be defined by form and location tolerances in the drawing. Using symbols, tolerances can be allocated to specific properties of the component, such as straightness, cylindricity, radial runout, etc.
What is the difference between form and location tolerances?
Whereas form tolerances define specific aspects of a solid (e.g. straightness or roundness) and thereby its form or shape, location tolerances always refer to a datum element or a datum axis (e.g. parallelism or perpendicularity).
How do form and location deviations arise?
Form deviations may be due to clamping forces, cutting forces, oscillations, or residual stress in the workpiece.
Location deviations can be the result of positional deviations of the machine, wrong machining temperatures, clamping forces, or residual stress.
The total deviations have a decisive impact on whether the component is functional or not.
Do form and location tolerances have to be indicated?
No. However, if no form and location tolerances are indicated, all deviations must be within the dimensional tolerances. We therefore recommend using only half the dimensional tolerance allowed if the functions of the components are important even though no form and location tolerances were indicated.
What should be kept in mind during measuring?
It is mandatory during measuring to observe the ‘datum element’ and ‘toleranced element’ indications in the drawing; otherwise, the measurement is invalid. Example: the component must not be clamped on the toleranced cylinder while checking the radial runout of the datum element. Instead, the radial runout of the toleranced element itself, i.e. the cylinder, must be checked.
