Overview
SIST ISO 866:2017 is an international standard that specifies the dimensions and designations of centre drills for centre holes without protecting chamfers (Type A). This standard focuses exclusively on metric dimensions, which are the only recommended sizes for this drill type going forward. Manufacturers have the discretion to produce these drills with either straight or spiral flutes, and unless otherwise stated, the drills are designed for right-hand cutting operations.
This second edition of the standard updates the prior version (ISO 866:1975) and includes an informative annex establishing relationships between ISO 866 designations and those used in ISO 13399, which covers cutting tool data representation and exchange.
Key Topics
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Scope and Coverage
SIST ISO 866:2017 applies to centre drills specifically without protecting chamfers - referred to as Type A. It excludes other types, which are governed by ISO 2540 (Type B) and ISO 2541 (Type R).
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Dimensions and Design
The standard defines exact dimensions for single-ended (for diameters ≤ 0.8 mm) and double-ended (for diameters ≥ 1 mm) centre drills. Detailed measurements include pilot diameter, shank diameter, overall length, and cutting length, with recommended values provided in metric units.
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Designation System
The standard outlines a clear designation format for Type A centre drills to ensure consistency and clarity:
- Term "Centre drill"
- Reference to standard (ISO 866)
- Type designation (A)
- Pilot diameter (mm)
- Shank diameter (mm)
Example: Centre drill ISO 866 - A 0.63/3.15
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Dimensioning Methods
Annex A presents two equivalent methods for dimensioning Type A centre holes to support rational drill selection and usage, including guidelines to maintain minimum length even after re-sharpening.
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Relationship to Other Standards
Annex B offers cross-referencing with ISO 13399 symbols for integration into tooling data systems and enhanced interoperability in manufacturing environments.
Applications
SIST ISO 866:2017 centre drills are essential for precision engineering tasks where accurate centre holes without chamfer protection are required. These drills are widely used in:
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Metalworking and Machining
Accurate formation of starter holes in workpieces for subsequent operations such as turning, drilling, or reaming.
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Tool and Die Making
High-precision centre holes facilitate alignment in assembly and machining processes.
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Automotive and Aerospace Industries
Ensuring dimensional accuracy in high-tolerance parts requiring centre holes without chamfers.
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Manufacturing Automation
Standardized dimensions and designations facilitate tool database integration and automated tool exchanges compliant with ISO 13399.
The standard helps manufacturers, engineers, and machine operators select appropriate centre drills that meet global quality and interoperability requirements, minimizing errors and enhancing productivity.
Related Standards
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ISO 2540: Centre drills for centre holes with protecting chamfer - Type B
Covers centre drills with a different chamfer design suited for applications requiring chamfer protection.
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ISO 2541: Centre drills for centre holes with radius form - Type R
Specifies dimensions and characteristics for centre drills featuring radius forms.
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ISO 13399 (all parts): Cutting tool data representation and exchange
Provides a comprehensive framework for tooling data management, enhancing the applicability of ISO 866 through consistent data standards.
Collectively, these standards ensure a coherent and interoperable approach to tool design, data exchange, and machining processes, supporting modern manufacturing industry requirements.
Keywords: ISO 866, centre drills, Type A centre drill, centre holes, without chamfer, metric dimensions, machining tools, cutting tool standards, ISO standards, precision drilling, manufacturing standards, tooling data exchange.
