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Surface Preparation

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Whichever Thermal Spray process is being used, the preparation of the surface (substrate) is critical so the overall success of the application. The most sophisticated and expensive Thermal Spraying equipment currently available could be utilised but it’s effectiveness would be negated if poor surface preparation techniques were used.

The most common method of surface preparation currently used is grit-blasting.

Some OEM user specifications still allow manual hand-operated grit-blasting cabinets to be used but due to the drive for a more repeatable process, fully automatic or semi-automatic blast units are now becoming the norm. 

Various types and sizes of grit are utilised depending upon the application.

The anti-corrosion industry generally uses low cost abrasive grit such as garnet or copper slag (a by-product from copper smelting). These types of abrasive grits are usually “one-use” grits and not recycled but if reliable collection, filtering and sieving systems are in place, they can sometimes be re-used one or two times.

More information on the methods used for surface preparation within the anti-corrosion industry can be found in the anti-corrosion section.

Do you Have Any Questions?

For reclamation work and all applications on machine elements, the most common abrasive blasting grit is Aluminium Oxide (Al2O3). It is used in blast cabinets and blast rooms (for larger components). The benefits of this blast media are many:

  • It can be recycled

  • It is almost totally inert so any imbedded particles do not cause corrosive cells

  • It is relatively cheap

  • It breaks down over time into smaller particles but importantly, these smaller particles remain sharp

Typical Blasting Cabinet

 

 

MBe Thermal Spray Services Ltd has over 30 years experience in the techniques and disciplines required to ensure that the surface is prepared correctly prior to the application of any Thermal Sprayed coating.

Some common areas of consideration and evaluation are as follows:

  • Component cleanliness prior to blasting process (degreasing)

  • Size and quality of blast media

  • Condition of blasting equipment

  • Correct air pressures

  • Quality of compressed air

  • Impingement angle of blast media

  • Inclusions of grit in the surface of the component (substrate)

  • Achieved surface profile

  • Operator/machine techniques

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