Overview
EN ISO 7285:2021 (identical to ISO 7285:1995) specifies the geometric and mechanical requirements, manufacturing, delivery and test specifications for pneumatic cylinders used on mechanized multiple spot welding machines. Published by CEN and adopted across European national standards bodies, this standard defines nominal strokes, bore sizes, mounting methods, force ratings and required inspections to ensure reliable, safe welding-cylinder performance.
Key topics and technical requirements
- Nominal characteristics
- Standardized nominal forces (kN at 1 MPa / 10 bar): examples include 2.19, 2.86, 3.61, 4.61, 5.92, 7.60, 9.74.
- Nominal strokes and recommended bore diameters and outside dimensions are specified (strokes from around 25 mm up to 160 mm; bore sizes and outside dimensions per annex C).
- Construction & mechanical performance
- Cylinders are double-acting with two piston stages for advance and one for return.
- Return force must be ≥ 40% of nominal force.
- Maximum supply pressure: 1.6 MPa (16 bar).
- Anti-rotation device must resist 150 N·m torque.
- Surfaces must be corrosion protected; seals compatible with lubricants.
- Mounting & electrode holder attachment
- Methods A–H for mounting are defined (annex A); electrode-holder attachment details in annex B.
- Electrode-holder attachment must be electrically insulated from the cylinder body (insulation test: 48 V d.c., resistance ≥ 1 MΩ).
- Testing & inspection
- Visual and dimensional inspections (per annex C).
- Leak tests with air immersed in water at 0.2 MPa and 1.0 MPa - no bubbles permitted.
- Pressure test: liquid (water) at 3.2 MPa (32 bar) for 1 min in each direction.
- Endurance (type) tests: defined cycle profiles, welding current by force rating, and post-test leakage/ play measurements.
Applications
- Use this standard when specifying or procuring pneumatic cylinders for mechanized multiple spot welding in automotive, appliance manufacture and industrial fabrication.
- Applicable to cylinder designers, welding-machine manufacturers, system integrators, test laboratories and quality/inspection teams to ensure interchangeability, safety and performance under welding conditions.
Who should use this standard
- Welding equipment manufacturers and mechanical designers
- Procurement and specification engineers
- Quality assurance and test laboratories
- Standards and compliance officers in manufacturing plants
Related standards
- ISO 4394-1 (fluid power - cylinder barrels) is referenced for tolerances and material requirements.
- Classified under ICS 25.160.30 (Welding equipment).
Keywords: EN ISO 7285:2021, pneumatic cylinders, multiple spot welding, electrode holder attachment, endurance test, leakage test, nominal force, mounting methods, ISO 7285:1995.
