Overview
ISO 12090-2:2011 specifies boundary dimensions and tolerances for profiled rail guides used in linear motion rolling bearings - specifically series 4 and 5. It covers profiled rails with one or more ball or roller carriages that use recirculating rolling elements to provide unlimited stroke. The standard defines nominal dimensions, symbols, design types (series 4: 4M; series 5: 5W), measurement datums and how carriage and rail elements may be combined within manufacturer limits.
Key topics and technical requirements
- Scope and definitions - precise terms for profiled rail, ball carriage, roller carriage, nominal width (A), height (H), carriage length (B), reference faces and symbols (per ISO 15241, ISO 1132-1, ISO 24393).
- Boundary dimensions - dimensional tables and figures for series 4 and 5 (rail width W, height H, bolt hole centres J, thread/designation G, etc.). Design details such as some thread/length variants are left to the manufacturer.
- Tolerances for geometric features - classes P5, P4, P3 are defined for running parallelism and dimensional deviations:
- Deviation of carriage height (∆H) and side-distance (∆A) for several carriages on one rail: ±0.04 mm (P5), ±0.02 mm (P4), ±0.01 mm (P3).
- Variation between several rails (V_H, V_A): 0.03 mm (P5), 0.015–0.02 mm (P4), 0.007–0.01 mm (P3) (values given per Table 4).
- Maximum permitted running parallelism (P_H, P_V) referenced to Figures 3 and 4 of the standard.
- Multi-piece rails - guidance for rails manufactured in two or more pieces for long stroke installations; marking and installation procedures are at manufacturer discretion.
- Length tolerances - Annex A specifies general length tolerances for profiled rails (examples: up to 6 mm ±0.1 mm; 6–30 mm ±0.2 mm; 30–120 mm ±0.3 mm; etc.).
Applications
ISO 12090-2:2011 is essential where standardized linear guide dimensions and precision are required:
- Design and specification of linear motion systems (machine tools, automation, precision stages)
- Manufacturing and quality control of profiled rails and carriages
- Interchangeability planning for multi-carriage assemblies and modular linear guides
- Procurement and technical compliance checks for linear guide components
Who should use this standard
- Mechanical engineers and system designers specifying linear motion components
- Bearing and linear-guide manufacturers and suppliers
- Quality and metrology engineers responsible for tolerance verification
- Procurement specialists sourcing profiled rail guides for industrial equipment
Related standards
Keywords: ISO 12090-2:2011, profiled rail guides, linear motion rolling bearings, boundary dimensions, tolerances, series 4, series 5, running parallelism, carriage, profiled rail.
