The Process

Thermal spraying, also commonly known as metal spraying is a surface engineering / coating process where a wide range of metals and ceramics can be sprayed onto the surface of another material.

Thermal spraying is widely used to provide corrosion protection to ferrous metals or to change the surface properties of the sprayed items, such as improve the wear resistance or thermal conductivity. The range of thermal spray applications is vast and a selection of them are summarised in our applications section link to applications. Other examples are shown in Applications. If you can’t find your application or want to learn more, please contact us or one of our resellers who will be pleased to help.

The Process Basics

the processAll methods of thermal spraying involve the projection of small molten or softened particles onto a prepared surface where they adhere and form a continuous coating. To create the molten particles, a heat source, a spray material and an atomisation/projection method are required. Upon contact, the particles flatten onto the surface, freeze and mechanically bond, firstly onto the roughened substrate and then onto each other as the coating thickness is increased.

The metal spray equipment falls into four main categories, Flame Spray, Arc Spray, Plasma Spray and High Velocity Oxygen Fuel (HVOF). More detailed information on each process can be viewed by clicking on the process tabs.

Materials, Accessories and Automation

An important part of the thermal spraying process are the spray materials and Metallisation can supply a wide range of quality thermal spray wires and powders.

To assist the thermal spraying process, we also offer a wide selection of accessories, from nozzle cleaners to masking products, DFT thickness gauges and deflected spray extensions to name just a few.

Metallisation also supply automation systems to automate production processes. These include LPG bottle spraying systems , aluminium multivoid tube spraying systems, ERW tube mills, pipe spraying systems, dust extraction, robotic installations and general thermal spray acoustic booths / turntables / manipulators.

  • Flame Spray Equipment
    • Gas fuel* and oxygen flame (*commonly propane or acetylene).

    • Wire or powder or ceramic rods

    • Compressed air (wire flame)

    • The gas fuel and oxygen are mixed and ignited to produce a flame. The material, either a wire or powder is fed into the flame. For wire flame spray, the material is melted and the compressed air, passing through a spray nozzle atomises the molten metal and sprays it onto the work piece. The larger the wire diameter, the higher the spray rate. For powder flame spray, the powder particles (metal or ceramic ) are softened in the flame and the speed of the flame gases through the nozzle sprays the softened powder onto the work piece.

  • Arc Spray Equipment
    • Electric Arc

    • Wire

    • Compressed air

    • Two wires (hence a common term for the process is Twin Wire Arc Spray), are fed into the pistol and electrically charged, one positive and one negative. The wires are forced together and form an electric arc, melting the wire. Compressed air, passing through a nozzle, atomises the molten metal and sprays it onto the work piece. There are three methods of wire feeding, push, pull and push/pull. The higher the current rating of the system, e.g. 350A, 700A etc., the higher the spray rate.

  • Plasma Spray Equipment
    • Plasma arc

    • Powder (ceramic, metal, plastics)

    • Via plasma jet

    • Plasma is the term used to describe gas which has been raised to such a high temperature that it ionises and becomes electrically conductive. In the case of Plasma spraying, the plasma is created by an electric arc burning within the nozzle of a plasma gun and the arc gas is formed into a plasma jet as it emerges from the nozzle. Powder particles are injected into this jet where they soften and then strike the surface at high velocity to produce a strongly adherent coating. The work piece remains cool because the plasma is localised at the gun.

    Plasma Spray Equipment
  • HVOF Spray Equipment
    • Fuel (liquid or gas) and oxygen flame

    • Powder (metal)

    • Via the flame

    • The fuel (liquid kerosene in our system) is mixed with oxygen and ignited. The combustion gases pass through a converging/diverging nozzle and accelerate to around 1,500m/sec. The powder is injected into the accelerated flame where it softens and gathers speed. The high impact speed of the particles produce a highly adherent, dense coating structure.

  • Materials & Accessories
    • Metallisation stock and supply a wide range of the most common thermal spray materials including wires and powders. Please review our materials section for our full range.

    • Metallisation stock and supply a wide range of thermal spray accessories to assist in the smooth running of equipment as well as sealers, masking products etc. For a sample of our accessories, please view our accessories section or contact Metallisation if we are not displaying your required items and we will endeavour to help.

    Materials & Accessories