ISO 10791-3:1998

Overview

ISO 10791-3:1998 - Test conditions for machining centres: Part 3 - defines geometric tests for machining centres with integral indexable or continuous universal heads (vertical Z‑axis). It applies to CNC machining centres that have basically six numerically controlled axes: three linear axes (X, Y, Z up to 2 000 mm) and three rotary axes (A or D and B on the head, and C' on the table). The standard specifies test methods (with reference to ISO 230‑1) to verify machine geometric accuracy but does not cover machine operation tests (no‑load/finishing performance tests are in other parts of ISO 10791).

Key topics and requirements

• Scope and configurations: Applies to machines with integral universal heads; three accessory head types are covered in annexes:
  • Annex A - 45° split indexable heads (tests AG1–AG9) - spindle resulting position checked
  • Annex B - integral swivel heads (tests BG1–BG7) - two NC rotary axes perpendicular
  • Annex C - 45° split continuous heads (tests CG1–CG7) - checks all contributing geometric features (excluding rotary positioning accuracy)
• Core geometric tests (examples from clause 4):
  • Straightness of linear motions (G1–G3) for X, Y, Z in vertical and horizontal planes; tolerances vary with travel (e.g., for X < 500 mm tolerance 0.010 mm; for 1 250–2 000 mm tolerance 0.025 mm)
  • Angular deviations of linear motions (G4) - pitch, yaw, roll; angular deviation limits expressed as ratios (reference values given in the standard)
  • Squareness between axes, spindle geometry, table/pallet checks and related tests to assess axes, planes and resulting spindle position
• Measurement practice: Uses SI units (millimetres for linear, ratios or angular units for angular deviations). Typical instruments include dial gauges (0.001 mm resolution), straightedges, taut wire, interferometers, precision levels and optical angular‑deviation devices.
• Reference and compliance: Test procedures reference ISO 230‑1 for installation, warm‑up, measuring methods and instrument accuracy. Software compensation may be used if agreed and should be declared in results.

Practical applications and users

• Who uses it:
  • Machine tool manufacturers for factory acceptance testing
  • End‑users and purchasing departments for acceptance and comparison of CNC machining centres
  • Metrology labs, service/maintenance engineers and quality teams for commissioning, troubleshooting and periodic verification
• Typical uses:
  • Acceptance testing and contractual verification of geometric accuracy
  • Baseline measurements for software compensation or corrective maintenance
  • Comparative benchmarking of machines and heads (indexable vs continuous universal heads)
  • Documentation for warranty and performance claims

Related standards

• ISO 230‑1:1996 - Test code for machine tools (geometric accuracy, referenced throughout)
• Other parts of ISO 10791 (Parts 1–11) covering horizontal spindles, axis repeatability, pallet accuracy, feeds/speeds, finished test pieces, contouring, cycle times, thermal distortion and noise emission

Keywords: ISO 10791-3:1998, geometric tests, machining centres, universal heads, indexable head, continuous head, vertical Z‑axis, CNC, straightness, angular deviation, spindle accuracy, ISO 230-1.