Overview
EN ISO 14921:2010 - Thermal spraying - Procedures for the application of thermally sprayed coatings for engineering components - specifies a general, process-oriented procedure for using thermal spray to enhance surface properties or to reclaim worn/non-conforming parts. It provides guidance on selecting spray procedures and materials but does not prescribe definitive methods for every application because component shapes and technological, physical and chemical requirements vary.
Key topics and requirements
- Scope and exclusions
- Applies to thermal spraying for surface improvement and repair of engineering components.
- Does not apply to thermally sprayed zinc/aluminium for atmospheric corrosion protection (see ISO 2063) or to self‑fluxing alloys that are fused after spraying (see ISO 14920).
- Component and coating design considerations
- Pre‑inspection (especially for repairs) to check geometry, cracks/defects, prior coatings and hardness.
- Evaluation of substrate suitability, accessibility and potential effects on fatigue and dimensions.
- Selection criteria for coating materials and spray processes based on bond strength, thickness, roughness, porosity, oxide content and expected service loads.
- Surface preparation and masking
- Methods for preparing the substrate surface before spraying, plus recommendations for masking and preliminary machining to ensure uniform coating thickness and proper edge conditions.
- Thermal spraying process
- Guidance on selecting appropriate spray technique and process parameters relative to material and component geometry (general conditions, not prescriptive settings).
- Inspection, sealing and finishing
- Post‑spray inspection requirements, sealing options if porosity is an issue, and finishing (machining/grinding) to restore required tolerances and surface characteristics.
- Documentation
- Requirements for record keeping; annexes include a flow chart for suitability assessment, a coating selection checklist and a process record template.
Applications and users
- Practical for: surface engineers, metallurgists, maintenance and repair shops, OEMs, coating contractors, quality and inspection personnel, and design engineers assessing repair or surface enhancement options.
- Typical applications: wear and corrosion resistance upgrades, reclamation of worn shafts/rollers/housings, electrical/thermal property restoration, friction modification and refurbishment of mechanical parts.
Related standards
- ISO 2063 - thermal spraying of zinc/aluminium for atmospheric corrosion protection
- ISO 14920 - thermal spraying of self‑fluxing alloys with subsequent fusing
- ISO 14923 - characterization and testing of thermally sprayed coatings
- EN 657:2005 - terminology/classification for thermal spraying
- EN 13507 - pre‑treatment of metallic parts for thermal spraying
- EN 15520 - design recommendations for components with thermally sprayed coatings
This standard is essential when planning, specifying or auditing thermal spray work to ensure consistent, documented procedures for coating selection, surface preparation, process control and final inspection. Keywords: thermal spraying, thermally sprayed coatings, ISO 14921, surface treatment, coating procedures, engineering components.
