ISO 4206:2016

Overview

ISO 4206:2016 defines the dimensional parameters and tolerances (in millimetres) for counterbores with parallel shanks and solid pilots intended for general use. This International Standard provides a consistent basis for manufacturers, designers and procurement specialists to specify counterbores that meet accepted tolerances and are compatible with common toolholder and piloting practices. The document includes a diagrammatic figure (Figure 1) and a tabulated set of dimensions and tolerances (Table 1); Figure 1 illustrates a counterbore with a cutting diameter greater than 5 mm.

Key Topics

• Scope and purpose: standardizes dimensions and limit deviations for counterbores with parallel shanks and solid pilots.
• Dimensions in millimetres: the standard specifies key dimensions such as cutting diameter, pilot diameter and shank diameter and associates each with tolerance classes.
• Diagrammatic guidance: Figure 1 is provided for orientation (not to convey construction details).
• Tabulated values: Table 1 lists dimension ranges and associated tolerances for ordering and manufacturing.
• Designation mapping: Annex A (informative) provides the relationship between ISO 4206 designations and preferred symbols in the ISO 13399 cutting-tool data representation scheme.
• Reference to ISO 286-2: tolerance classes and limit deviations reference the ISO 286-2 code system for linear sizes.

Practical keywords: counterbores, parallel shanks, solid pilots, dimensions, tolerances, ISO 4206:2016, interchangeability, tooling, CNC compatibility.

Applications

ISO 4206:2016 is directly applicable where controlled fit, repeatable assembly and tool interchangeability are required. Typical applications include:

• Production and procurement of hand and machine counterbores for secondary machining operations.
• Specification of tooling for CNC machining centers where consistent pilot and shank dimensions support accurate location and repeatable cycles.
• Sourcing and quality control of interchangeable cutting tools across suppliers and workshops.
• Integration with tooling databases and CAM/CNC systems when combined with ISO 13399 designations (Annex A).

Benefits:

• Interchangeability across manufacturers and toolholders.
• Consistent quality control through standardized tolerances.
• Improved CAD/CAM interoperability by mapping to ISO 13399 symbols.

Related Standards

• ISO 286-2 - Geometrical product specifications (tolerance classes for holes and shafts), referenced for tolerance class definitions.
• ISO 13399 - Cutting tool data representation and exchange; Annex A of ISO 4206 links designations to ISO 13399 symbols.
• ISO 4205 - Countersinks with parallel shanks and solid pilots (related tooling family).

Use ISO 4206:2016 when specifying or manufacturing counterbores to ensure dimensional conformity, reliable piloting and compatibility with industry tooling systems.