ISO 11901-3:2021

Overview

ISO 11901-3:2021 - Tools for pressing - Gas springs - Part 3 defines requirements for nitrogen-filled gas springs with increased spring force and compact built height used in press tools. The standard covers dimensional specifications (millimetres), nominal initial forces, types (type 1 700 to 200 000), marking, technical delivery conditions and designation. It ensures interchangeability, safe pressurization and consistent supply conditions for high-force gas springs used in industrial pressing applications.

Key topics and technical requirements

• Scope and range: Gas springs of types 1 700 to 200 000 with nominal initial forces from 1 700 N to 200 000 N (tolerance ±5 %). Intended specifically for use in press tools.
• Dimensions & interchangeability: Detailed tables and figures specify lengths, diameters, mounting hole patterns and other critical dimensions. General tolerances follow ISO 2768-m.
• Filling pressure limits: Maximum filling pressures differ by type (smaller types can be filled up to 18 MPa; many larger types up to 15 MPa - see tables in the standard).
• Pressure filling inlet:
  • Types < 42 000: M6 thread
  • Types ≥ 42 000: ISO 7 - Rp 1/8 (pipe thread per ISO 7-1)
  • For types 1 700 and 3 200 the inlet is located on the bottom.
• End-of-stroke behaviour: End-of-stroke nominal force increase coefficient specified (range 1.5 to 1.8, depending on stroke).
• Marking: Gas springs must be indelibly labelled with at least the manufacturer’s name, gas used (nitrogen), date of manufacture, maximum filling pressure and type.
• Technical delivery conditions: Supplied at nominal pressure at 20 °C. Rods are to be slightly oiled and protected. Pressure varies with temperature per p = p0 (1 + 0.0036 Δt).
• Designation: Standardized designation format - e.g. “Gas spring ISO 11901-3 - 15 000 × 25” (type × nominal stroke). Note: mounting accessories are specified in ISO 11901-2.

Applications and who uses it

• Intended users: press tool designers, toolmakers, die manufacturers, equipment OEMs, procurement and quality/compliance teams.
• Practical uses: specification and selection of compact, high-force gas springs for pressing, stamping, forming and die operations where high initial force in a compact envelope and reliable interchangeability are required.

Related standards

• ISO 11901-2 - Specification of mounting accessories for gas springs.
• ISO 7-1 - Pipe thread dimensions and designation (used for larger filling inlets).
• ISO 2768-1 - General tolerances for linear and angular dimensions.

Keywords: ISO 11901-3, gas springs, press tools, nitrogen-filled, compact built height, increased spring force, M6 thread, ISO 7 Rp 1/8, nominal initial force, dimensions.