Overview
ISO 6537:1982 specifies requirements for non‑ferrous metallic pneumatic cylinder tubes (cylinder barrels) used in pneumatic fluid power systems. The standard covers round tubes (seamless or welded) in the as‑drawn stress‑relieved or fully heat‑treated condition, and bores with special finishing (with or without metal removal). It defines mechanical properties, dimensional tolerances, surface finishes and technical delivery conditions for tubes intended as pneumatic cylinder bodies. Annex A gives inside‑diameter dimensions and tolerances; Annex B provides a recommended method of ordering.
Key topics and technical requirements
- Materials: Brass and aluminium are the metals explicitly retained in the standard (other non‑ferrous metals may be suitable by agreement).
- Manufacture and condition: Tubes may be supplied as-drawn & stress‑relieved, fully heat‑treated, or with special finishing for welded tubes.
- Mechanical and chemical properties: Alloy, metallurgical state or agreed mechanical/chemical property values must be defined by tube and cylinder manufacturers.
- Dimensional tolerances:
- Inside‑diameter tolerance classes conform to ISO 286 (H11, H12, H13, H14).
- Wall thickness tolerances and allowable eccentricity are defined (see standard tables).
- If both inside and outside diameters are specified, outside diameter tolerance must ensure required wall thickness across the length.
- Rectitude (straightness):
- Measured against a 1 006 mm straight edge or by rolling on two rollers; specific limits depend on tube length (for lengths >1 000 mm, deviation must not exceed L/1 000).
- Surface finish:
- Bore surface roughness specified in terms of Ra and Rmax (ISO 468). Measurements are taken at multiple circumferential points; special finishing methods are defined for bores requiring tighter finishes.
- Operating limits:
- Recommended maximum normal working pressure generally limited to 25 bar (standard nominal pressures: 6.3, 10, 16, 25 bar).
- Service temperature range to be covered by manufacturer at minimum −40 °C to +100 °C.
- Delivery, packaging and inspection:
- Protection and packaging by agreement; test certificates are supplied only if requested. Annex B lists the ordering information items.
Practical applications and users
ISO 6537 is intended for:
- Pneumatic cylinder manufacturers and designers specifying cylinder barrels.
- Tube producers and suppliers of aluminium and brass tubes for pneumatics.
- Procurement and quality engineers setting purchase specifications and inspection criteria.
- Design engineers ensuring compatibility of bore finish, tolerances and operating pressure/temperature.
Using ISO 6537 helps ensure interchangeability, reliable cylinder performance and reduced rework when integrating non‑ferrous tubes into pneumatic systems.
Related standards
- ISO 286 - Tolerances and fits
- ISO 468 - Surface roughness parameters and specification
- ISO 3322 - Pneumatic cylinders - Nominal pressures
- ISO 5598 - Fluid power vocabulary
- ISO 460 - Surface roughness (parameters and rules)
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