Overview
ISO 2541:2016 defines the dimensions and designation of centre drills for centre holes with a radius form - Type R. The standard covers only metric dimensions, designates drills by type and diameters (example: R 2,5/6,3), and notes that flutes may be straight or spiral at the manufacturer's option. Unless stated otherwise, these drills are right‑hand cutting. Annex A provides recommended dimensions for the matching centre holes; Annex B maps designations to the ISO 13399 cutting‑tool data representation scheme.
Key Topics
- Scope and designation
- Specifies Type R centre drills and how to designate them (Type R, pilot diameter, shank diameter).
- Dimensional data
- Provides nominal metric sizes (pilot diameters and matching shank diameters), overall lengths, usable lengths and radii in a tabulated format. Some sizes are shown in brackets and “should be avoided whenever possible.”
- Tolerances and geometry
- Machine‑side tolerance classes and common tolerances (e.g., h9 for shank fits) are referenced; the standard also specifies point geometry (120° point angle indicated in figures).
- Manufacturing options
- Flutes may be straight or spiral; drills are generally right‑hand cutting unless otherwise specified.
- Supporting information
- Annex A (normative) gives recommended centre‑hole dimensions for Type R.
- Annex B (informative) provides relationships between ISO 2541 designations and ISO 13399 symbols for data exchange.
Applications
ISO 2541:2016 is practical for professionals and organizations involved in:
- Tool manufacturers specifying and producing centre drills to standardized dimensions.
- Tooling suppliers and procurement ensuring compatible drill sizes and shank fits for lathes and turning centers.
- Machine shops and CNC programmers using centre drills to create accurate centre holes for turning between centers, workholding, and setup operations.
- Quality, inspection and metrology teams verifying drill dimensions, fits and tolerances against a recognized international standard.
- Design and engineering departments that include centre‑hole geometry in part and fixture designs.
Using ISO 2541:2016 helps ensure interchangeability, predictable fit between drill and workpiece, and consistent setup practices across suppliers and workshops.
Related Standards
- ISO 13399 (all parts) - cutting tool data representation and exchange (relationship provided in Annex B)
- ISO 866 - centre drills Type A (without protecting chamfers)
- ISO 2540 - centre drills Type B (with protecting chamfer)
Keywords: ISO 2541:2016, centre drills, Type R, centre holes, metric dimensions, flutes straight spiral, right‑hand cutting, pilot diameter, shank diameter, ISO 13399, cutting tools, machining.
