Lesson 3: Methods that meet today’s requirements – flame metal spraying

In this lesson, we will explore one of the methods that meets today’s requirements for cost-effective individual and small series production, as well as achieving quality and durability exceeding the original – Flame Metal Spraying.


In order to meet the new requirements for repair and renovation, i.e. to achieve cost-effective individual and small series production, and to achieve quality and durability that exceeds the original, the following methods have been widely used: 

  • Flame spraying of metallic powder
  • Flux cored metal spraying welding
  • Casting repair welding
  • Hard metal surfacing
  • Application of plastics

Flame Metal Spraying

  • Overview
    • Flame metal spraying, or more accurately, cold metal powder spraying, is a method that addresses these needs effectively.
    • Basic equipment such as acetylene and oxygen cylinders is readily available, making it accessible even in simple locksmith shops.
    • A wide range of alloy powders is commercially available.
    • The process involves depositing spherical alloy powder onto the surface to be treated using a mixture of acetylene and oxygen, which becomes plasticized by heat.
  • Procedure
    • The sequence of operations includes preparation and cleaning of the component, pre-machining of the surface, application of a primer coat, application of filler powder, finishing, and quality control.
    • Preparation involves cleaning the surface from physical and chemical contamination and testing its suitability.
    • Pre-machining and roughening prepare the part’s shape and surface for bonding.
    • Primer powder ensures stable adhesion.
    • Filler powder composition is selected based on component material and expected stresses.
    • Topcoat application follows specific rules like spray temperature control and machining allowance.
  • Advantages
    • Cold metal spraying offers flexibility in varying alloying elements.
    • The resulting surface is corrosion-resistant and has excellent lubrication properties.
    • Surface hardness can be controlled, making it suitable as a replacement for other surface treatments.
  • Limitations
    • Not suitable for dynamic loads.
    • Unsuitable for point or linear contact.
    • Should not be used in areas subject to high thermal stress.
    • Applied layers can be porous.
  • Applications
    • Flame metal spraying finds applications in shaft bearing locations and bearing bushes.


  • Flame metal spraying, or cold metal powder spraying, is a method that meets modern requirements for cost-effective repairs and renovations.
  • It offers flexibility in alloy composition, corrosion resistance, and controlled hardness.
  • While it has limitations, it is a valuable technique for specific applications.

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