ISO 8167:2021

Overview - ISO 8167:2021 (Resistance welding - Embossed projection welding)

ISO 8167:2021 defines the geometries, dimensions and designation of embossed projections used for projection welding (resistance welding). It covers spherical, ring-shaped and elongated projections formed on sheet components - and includes informative annexes with tool examples and alternative dimensions. The standard applies to hot‑rolled, cold‑rolled, coated and uncoated steels, stainless steels and nickel alloys for conventional welding quality up to 3 mm sheet thickness. Solid projections are excluded.

Key topics and technical requirements

• Types of projections:
  • Spherical (SP) - recommended for sheet thickness ≥ 1 mm.
  • Ring‑shaped (RP) - usually for sheets < 1 mm.
  • Elongated (EP) - used where a pair of spherical/ring projections would otherwise be used.
• Dimensions and tolerances: Nominal projection diameter/width and projection height are specified with tolerances; projection diameter, width and height tolerances are given in detailed tables. For multiple projections welded in one operation, individual projection heights shall not vary by more than 5%.
• Material and thickness guidance: Projection dimensions are selected based on the thinner sheet of a lap assembly and, for dissimilar materials, are made in the material with lower thermal conductivity and/or higher strength.
• Tooling: Annex B provides examples of punches/dies (e.g., truncated cone and radiused cone punches) and guidance on punch‑tip geometry. Annex C gives alternative projection and tool dimensions.
• Selection groups: Annex A groups projection diameters into Group A, B, C by sheet thickness to simplify selection for space, marking and strength requirements.
• Designation: Projections are designated as: “Projection ISO 8167-<type code><size>” (e.g., Projection ISO 8167-SP2,5).

Practical applications and users

ISO 8167:2021 is intended for professionals involved in resistance projection welding and related manufacturing processes:

• Welding engineers and WPS authors specifying projection geometry for consistent weld quality.
• Toolmakers and die designers developing punches and dies to form embossed projections.
• Quality managers and inspectors verifying projection dimensions and tolerances in production.
• Automotive, appliance, electrical, and general metal‑fabrication OEMs where projection welding is used for high‑speed assembly of thin sheet parts.

Practical benefits include predictable weld collapse, repeatable current flow paths, reduced electrode wear and consistent mechanical strength of projection welds.

Related standards

• ISO 17677‑1 - Resistance welding vocabulary (spot, projection and seam welding), referenced for terms and definitions used in ISO 8167:2021.

Keywords: ISO 8167:2021, embossed projection welding, projections for resistance welding, projection dimensions, spherical projection, ring‑shaped projection, elongated projection, projection welding tools, resistance welding.