Overview
ISO 8636-1:2026 defines comprehensive test conditions for bridge-type milling machines with a fixed bridge (portal-type). Developed by the International Organization for Standardization (ISO), this standard specifies geometric and positioning accuracy tests for numerically controlled axes, referencing ISO 230-1 and ISO 230-2 for consistency. It provides acceptance criteria in the form of tolerances and is specifically applicable to machines featuring a moving table and fixed double columns.
The standard does not apply to single-column (open-sided) machines, fixed-table machines with moving columns, or the operational testing of machines (such as vibration or noise checks), and focuses only on verifying machine geometric and positional accuracy. ISO 8636-1:2026 establishes unified terminology for principal machine components and axis designation, aligning with ISO 841, and aims to ensure consistent quality control and performance across different markets.
Key Topics
- Geometric Accuracy Testing: Procedures for verifying the linear and angular accuracy of machine axes, ensuring the bridge-type milling machine meets predefined performance tolerances.
- Positioning and Repeatability: Methods for checking the accuracy and repeatability of numerically controlled axes, supporting high-precision machining applications.
- Machine Configuration Coverage: Applies to fixed-bridge, double-column portal-type milling machines with moving tables; excludes open-sided and moving-column designs.
- Reference Documents: Relies on ISO 230-1, ISO 230-2, and ISO 230-7 for test methods, measuring equipment use, and installation prerequisites.
- Terminology and Axis Designation: Provides standardized definitions and labels for principal components and directions of movement, facilitating international understanding.
- Test Sequence and Conditions: Guidance on test order flexibility, measurement conditions (e.g., machine leveling and temperature), and agreement protocols between users and manufacturers.
- Measurement Tools and Uncertainty: Recommends suitable instruments (e.g., dial gauges, straightedges, lasers) and highlights the importance of measurement uncertainty.
- Tolerance Criteria: Offers applicable tolerances for the tested machine parameters, with default minimum recommendations and the possibility for agreement-based customization.
- Software Compensation: Addresses use and reporting of built-in software compensation for geometric or positional deviations.
Applications
- Machine Acceptance and Certification: Used by manufacturers and end users to verify that new fixed-bridge portal-type milling machines conform to relevant accuracy and repeatability specifications before installation or commissioning.
- Quality Management in Manufacturing: Helps machine tool builders and precision machining facilities maintain consistent product quality through objective, standardized measurement procedures.
- Maintenance and Servicing: Provides a structured approach for ongoing verification during the service life of a machine, supporting preventive maintenance and early detection of mechanical deviations.
- Procurement and Contract Specification: Offers clear criteria and shared terminology, enabling buyers and suppliers to define and agree on acceptance tests and associated expenses within machinery procurement contracts.
- International Trade Facilitation: Supports global interoperability by harmonizing test conditions and terminology, reducing technical misunderstandings and non-conformities across borders.
Related Standards
- ISO 230-1:2012 – Test code for machine tools-Geometric accuracy of machines operating under no-load or quasi-static conditions.
- ISO 230-2:2014 – Test code for machine tools-Determination of accuracy and repeatability of positioning of numerically controlled axes.
- ISO 230-7:2015 – Test code for machine tools-Geometric accuracy of axes of rotation.
- ISO 841 – Numerically controlled machine tools-Coordinate systems and motion nomenclature.
- ISO/TR 16907 – Numerical compensation of geometric errors.
- ISO/TR 230-11 – Guidance on measuring instruments and uncertainty in machine tool testing.
ISO 8636-1:2026 provides a practical, harmonized framework for ensuring the geometric and positional accuracy of bridge-type milling machines, supporting precision, reliability, and international best practice in machine tool performance verification.
Open preview (PDF)Machine tools — Test conditions for bridge-type milling machines — Part 1: Testing of the accuracy of fixed bridge (portal-type) machines
