ISO 16432:2006

Overview

ISO 16432:2006 - "Resistance welding - Procedure for projection welding of uncoated and coated low carbon steels using embossed projection(s)" - sets out requirements for embossed-resistance-projection welding of two-sheet assemblies of low carbon steel (single sheet thickness 0.4 mm to 3 mm). The standard covers uncoated steels and a range of metallic coatings (hot‑dip zinc/galvannealed, electrolytic zinc/zinc‑iron/zinc‑nickel, aluminium, and zinc‑aluminium). Organic- or primer-coated steels are excluded. Annexes provide guidance on equipment, projection/weld relationships and typical welding conditions.

Key Topics

• Scope & materials: Applicable steel forms, acceptable coatings, and surface condition requirements (free of contaminants; pickled hot‑rolled uncoated steel).
• Projection geometry: Use of embossed projections per ISO 8167; projection base diameter linked to sheet thickness; projection height uniformity within ±5%.
• Design rules: Edge distance minimum 1.25 × projection base diameter (db); minimum weld pitch 4.5 × db; for dissimilar thicknesses, projections should be formed in the thicker sheet and sized for the thinner sheet.
• Projection collapse limits: Maximum permissible reduction in projection height (cold collapse) not to exceed 20%.
• Welding equipment & tooling: Requirements for welding machines, electrode assemblies, contact face, inserts and cooling (guidance in informative Annex A).
• Testing & qualification: Type and routine tests for weld diameter, fracture modes, weld strength, visual/metallographic checks and distortion (references to ISO test methods).
• Process control: Guidance on weld arrays, current distribution, pitch tolerance (±10% linear pitch) and adjustments for coated steels.

Applications and Who Uses It

ISO 16432:2006 is used by:

• Welding engineers and procedure developers who create and qualify projection welding procedures for low carbon steels.
• Quality/control engineers responsible for weld assessment and routine testing in manufacturing.
• Fabricators and OEMs in industries that join coated or uncoated low carbon steel sheets (for example, automotive body components, white goods, HVAC and general sheet‑metal assemblies). It helps ensure repeatable, robust embossed projection welds and informs tooling design, process parameters and inspection criteria.

Related Standards

Key referenced documents (useful when applying ISO 16432:2006):

• ISO 8167 - Projections for resistance welding
• ISO 669, ISO 5182 - Equipment and electrode materials
• Test methods: ISO 10447, ISO 14270/72/73, ISO 14329
• Welding procedure specs: ISO 15609-5, ISO 15614-12

This standard is practical for specifying projection welding procedures, designing joint geometry and ensuring compliance with repeatable resistance welding quality for coated and uncoated low carbon steels.