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JUN 2022

The Powder Coating Process – Noble Metal Coating

In general, Powder Coating can be seen as an environmentally friendly method of applying a finish, especially as it does not utilise solvent-based paints, prevents overspray waste, and allows for full recycling and reuse of any unused powder.

Although powder coating was first intended to be used to polish metal, thanks to advancements in technology, it is now frequently used to finish ceramics, plastics, and even wood.

According to research, powder coating is the coating medium that is expanding the fastest, and given the benefits to the environment and its superior finishing capabilities, this trend is likely to continue.

powder coating types

Thermosets and thermoplastics are the two basic forms of powder coatings.

The performance attributes are improved with thermosetting variations because as the powder bakes, it reacts with compounds in the polymer to enhance molecular weight.

Thermoplastic kinds do not notably alter or undergo any further reactions; instead, they just flow into the finished coating.

Application of powder coating

Stage 1:Pre-treatment stage

In order to obtain the greatest finish possible, preparation is crucial in this case as it is in every painting application.

Oils, lubricants, and metal oxides must be removed, and this is normally done using a number of chemical and mechanical processes, depending on the material, size, and finish that is needed.

Phosphates or chromates are frequently used in submersion or spraying during the multi-stage chemical pre-treatments.

My preference is for companies that offer phosphate preparations because chromates can be hazardous to the environment.

Sandblasting and shot-blasting are additional surface-preparation techniques in which blasting abrasives are employed to provide surface texture and prepare glass, plastic, or wood.

Metals can be ground with silicon carbide, and aluminum-sensitive plastic abrasives can be used in plastic media blasting.

Stage 2: Applying the powder

The most popular technique is using a spray pistol for electrostatic spraying.

The powder is given a positive electric charge by the gun while the object is grounded. The powder is then sprayed and driven toward the component by the strong electrostatic charge.

When the component is heated, the powder melts into a consistent layer, which is then chilled to create a hard coating. On occasion, we heat the metal first before applying the powder to the hot surface. Preheating can aid in achieving a more uniform finish, but it can also lead to other issues, such as runs brought on by too much powder.

Electrostatic discs that have been specially designed can also be used to apply powder.

Another technique, referred to as the fluidized bed method, is heating the substrate before dipping it into a bed of powdered air.

Further heating is necessary to complete curing the coating once the powder clings and melts to the heated object. This technique is typically applied when the coating is larger than 300 microns.

The same fluidizing methods as above are used in electrostatic fluidized bed coating, but with significantly less powder depth in the bed. The powder becomes charged as the fluidizing air pulls it up due to electrostatic charging that takes place in the bed. Above the fluid bed, a cloud of charged powder particles forms. The particles will be drawn to the charged cloud’s surface when a grounded component passes through it. There is no heating of the parts.

The Electrostatic Magnetic Brush (EMB) coating process uses a roller to apply powder coating to flat objects.

Stage 3: Healing

Thermoset powders begin to melt, flow out, and then react to produce a higher molecular weight polymer when they are exposed to high temperature increases (often via a convection or infrared cure oven). For this cross-linking cure procedure to fully cure and develop the entire film qualities for which the material was intended, a specific temperature must be maintained for a specific period of time.

What are the disadvantages of Powder Coating

  • Very thin coatings can show pinholes
  • Very frequent colour changes can be time consuming
  • Inside corners can have low film thickness
  • Can be tricky on sharp corners
  • Needs expertise to maintain uniformity of thickness
  • Colour matching and uniformity can be harder than with liquid paints

What are the advantages of Powder Coating?

  • Environmentally friendly – no solvents required
  • Cost-effective
  • Finishes are tough and flexible making it harder to chip or crack
  • Generally gives a 100% solid coating
  • Almost no waste produced
  • Massive range of colours and finishes
  • Rust free
  • Can be applied over a wide range of thicknesses
  • Can produce thick coatings without running or sagging
  • Special effects are easily accomplished
  • Fast turnaround times
  • Protection against external UV fading
  • Exceptional colour retention
  • Excellent electrical insulation capabilities
  • Resistant to most chemicals and solvents

Conclusions

Even in the roughest settings, Powder Coating Dubai , a cost effective technology, provides outstanding durability and gives good resistance to scratches and chemical corrosion. It also completes the product’s desirable aesthetic attributes.

With this technology, powders are instantly usable and do not need to be mixed, which eliminates finish variables, shortens processing times, and produces excellent film qualities.

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