Geometriareikäkoko

Geometriareikäkoko is a term used in Finnish engineering to describe the size and geometry of holes in parts and assemblies. The word combines geometria (geometry), reikä (hole), and koko (size). In practice, it denotes how a hole is specified in design drawings, including its shape, size, and allowable variation.

Elements of geometriareikäkoko include the nominal diameter for circular holes or length and width for slots, the hole shape, edge conditions (bore, countersink, chamfer), and tolerances or datum references used to locate the hole. It may also cover orientation and concentricity relative to mating features.

Standards and methods: Hole geometry is typically defined using standard drawing conventions or geometric dimensioning and tolerancing (GD&T). Specifications may specify nominal size, tolerance class, and geometric tolerances such as position, perpendicularity, or runout. In Finnish practice, geometriareikäkoko is expressed through a combination of size tolerances and GD&T callouts.

Manufacturing and measurement: Holes are produced by drilling, reaming, or boring, with finishing operations affecting final size. Measurement methods include calipers, micrometers, gauge pins, or coordinate measuring machines (CMM). Consistency with geometriareikäkoko ensures proper fit of fasteners and assemblies.

Applications: The concept is relevant to mechanical engineering, sheet metal work, piping, and electronics housings where precise hole geometry governs assembly quality. Designers balance functional requirements with manufacturability to determine appropriate hole geometry and tolerances.