ISO 18278-3:2017

Overview

ISO 18278-3:2017 - "Resistance welding - Weldability - Part 3: Evaluation procedures for weldability in spot weld bonding" specifies standardized test procedures for evaluating spot weld bonding performed by resistance spot welding combined with adhesive bonding. The standard defines how to determine the acceptable welding current range and to estimate electrode life for prepared assemblies of uncoated and coated metal sheets with individual thicknesses from 0.4 mm to 6.0 mm.

Key topics and technical requirements

• Scope and purpose: Procedures to assess weldability in spot weld bonding (resistance spot welding through an adhesive or sealant).
• Weld bonding equipment: Requirements for electrodes (per ISO 5182 / ISO 5821), adhesive dispensing, storage chamber temperature control and welding current setup.
• Welding current: Type (AC or DC) must be recorded; for AC, welding current shall be not less than 30% RMS at full conduction angle. Constant-current control is required.
• Mechanical settings: Recommendations to reduce electrode impact (e.g., electrode approach speed ≈ 0.15 m/s, peak force < 150% of nominal) and sufficient squeeze time to avoid bounce.
• Electrode cooling: Inlet water temperature should be maintained near 20 °C and not exceed 30 °C; minimum water flow 4 l/min per electrode; cooling layout and dimensions per ISO 5821.
• Measurements and test methods: Methods for measuring welding current, electrode force (per ISO 18278‑1), ambient temperature, adhesive amount, weld diameter (per ISO 17677‑1), and detection of expulsion via voltage/force/displacement traces or visual inspection.
• Test procedures: Defined procedures for determination of welding current range, electrode life tests, assembly preparation, preliminary adjustments, and reporting requirements (test report contents specified).

Practical applications and users

ISO 18278-3:2017 is used to:

• Qualify materials, electrode designs and welding parameters for spot weld bonding.
• Develop robust production process windows (acceptable current range) and predict electrode maintenance intervals (electrode life).
• Support supplier/customer qualification, production engineering and failure analysis.

Typical users:

• Welding and process engineers
• Quality assurance and test laboratories
• OEMs and suppliers involved in metal joining and adhesive/spot-weld hybrid assemblies
• Equipment manufacturers and R&D teams optimizing electrode design and cooling

Related standards

• ISO 18278-1:2015 (general requirements for weldability evaluation)
• ISO 669 (resistance welding equipment requirements)
• ISO 5182 (electrode materials)
• ISO 5821 (spot welding electrode caps)
• ISO 17677-1 (vocabulary and weld diameter measurement)
• ISO 14373 (spot welding procedures for steels)

Keywords: ISO 18278-3:2017, resistance welding, spot weld bonding, weldability, welding current range, electrode life, adhesive bonding.