ISO 3875:2020

Overview

ISO 3875:2020 - Machine tools - Test conditions for external cylindrical centreless grinding machines - Testing of the accuracy defines standardized methods to verify the geometric accuracy, positioning repeatability and machining performance of general-purpose and normal-accuracy manual and NC (numerically controlled) external cylindrical centreless grinding machines. The standard focuses exclusively on accuracy verification (geometric tests, machining tests and axis positioning tests) and specifies applicable tolerances. It does not cover dynamic machine operation (vibration, noise, stick–slip) or machine characteristics such as speeds and feeds.

Key topics and technical requirements

• Scope: Tests for external cylindrical centreless grinding machines (types 1–3 machine configurations) and NC axes (X1, X2, Z1, U, V, W, P, R) with terminology referenced to ISO 841.
• Test categories:
  • Geometric tests (straightness, parallelism, alignment of grinding and regulating wheel components).
  • Accuracy and repeatability of positioning for manual, automatic and numerically controlled (NC) linear axes.
  • Machining tests (finishing cuts only) including in‑feed and through‑feed grinding checks.
• Measurement principles:
  • Linear units in millimetres (mm); angular values in degrees or ratios (μrad/arcsec for clarity).
  • Minimum tolerance consideration: 0.002 mm when adapting tolerances to different measuring lengths.
  • Use of appropriate measuring instruments (DTIs, LVDTs, non‑contact sensors, straightedges), with measurement uncertainty guidance from ISO 230‑1 and ISO 230‑2.
• Test execution notes:
  • Machine levelling per manufacturer and ISO 230‑1 recommendations.
  • Tests may be selected by agreement for acceptance; sequence flexible to ease instrument setup.
  • Software compensation for geometric/thermal errors may be used only by prior agreement and must be reported.
• 2020 updates: expanded wheel thickness coverage (>300 mm for some tests), classification of machine configurations, and a new Z‑directional grinding wheel slide test.

Applications and users

ISO 3875:2020 is used for:

• Acceptance testing and commissioning of centreless grinding machines.
• Supplier–buyer contractual specifications and factory acceptance tests (FAT).
• Quality assurance, machine tool metrology and maintenance verification.
• Calibration and capability assessment in testing laboratories and manufacturing plants. Typical users: machine tool manufacturers, metrology labs, production engineers, maintenance teams, QA managers, and procurement specialists.

Related standards

• ISO 230‑1:2012 - geometric accuracy test code (installation/measurement uncertainty).
• ISO 230‑2:2014 - accuracy and repeatability of NC axes.
• ISO 841 - designation of axes.
• Informative references: ISO/TR 16907, ISO/TR 230‑11.

Keywords: ISO 3875:2020, centreless grinding machines, external cylindrical centreless grinding, geometric tests, positioning accuracy, NC axes, machine tool testing, machining tests, tolerances.