Powder coating services

It is understandably apparent that the customer base of today expects quality, strength, and dependability from products they purchase. The customer wants his or her products to provide the optimum in performance, and when it comes to the powder coating services industry, the customer wishes the finish of his part to look nice and to resist any form of corrosion, in order that the product lasts for a considerable period of time. The finishing processes, considered best are designed to perform as just described.

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powder coating differs from painting


There are no solvents or liquids which to contend in making use of the powder coating process. It is the ultimate coating in way of friendliness to the surrounding environment. The powder, due to its characteristic of being dry, allows for the reclamation the over-spray. The powder makes use of heat, in order to convert from its initial powder form to a continuous film. Powder materials, in general are plastics. The plastics are ground down to a powder. The powder is formed using pigments, plastic resins, flow agents, and other specialised materials and ingredients which provide the desired formation of the coating film.


The powder coating includes two basic classifications Thermoplastic and Thermoset powders


Thermoplastic powders are applied to a surface which has been preheated. The temperature is higher than the melting point of the powder. Material, thermoplastic in nature, when applied to a very hot surface naturally melts. There is a fusion bond to the surface and a flow out in way of a durable continuous film. When the preceding film cools down, certain physical properties develop. The most common of thermoplastic powders is nylon powder. The thermoplastic coating is known for its longevity and resistance to chemicals.


The Thermoset powders possess a heat activated catalyst. The thermoset powders are normally applied to a surface at an ambient temperature. The powder and surface are heated and as the temperature increases, past the melt point of the powder 250-275F---it melts and fusion bonds to the surface. The continual rise of the temperature--360-380F---produces a heat sensitive catalyst and causes the molecular structure of the material to change. The temperature is maintained while the material cures and forms a durable, hard continuous film. The Thermoset powder coating system provides the consumer with a great deal of flexibility with regard to formulation. The powders, within this category, are very strong and are used far and wide with respect to decorative applications and functional type of applications.


Functionally, then, with respect to the powder coating process is sectioned off into four functions


1) Prepping of the surface


2) Application of the powder


3) Heating of the part and


4) Curing of the coating.



Preparation of the surface area


The prepping of the surface begins with a process that assures the surface is cleaned properly. The clean surface is free of soil or the greases of the manufacturing process. Other surface treatments, in way of prepping might include blasting and using iron phosphate or zinc phosphate---depending upon the long-term corrosive performance required.


(Note Zinc phosphate (Zn3(PO4)2) is an inorganic chemical compound. It is used as a corrosion resistant coating on the surface of metal. Its application is relative to that of an electroplating process or it is applied as a primer pigment. Electroplating is the plating process relative to plating one metal onto another metal by hydrolysis with the objective of decoration in mind or in order to prevent deterioration of the part by way of corrosion to the metal. It is used in lieu of toxic materials which were prior lead based or chromium in nature. By 2006, Zinc phosphate became the standard inhibitor of corrosion. Zinc Phosphate coats best on a crystalline structure as opposed to bare metal. A seeding agent is frequently used as a pretreatment A common agent, used, in this regard is sodium pyrophosphate.)


Thermoplastic powders require the primer in order to properly promote adhesion. The thermoset powders do not require a primer since the adhesion promoter is built into the material. Primers, nevertheless, may be used with respect to thermoset powders in order to provide enhancement of particular properties. In any event, the priming material which is used must possess the feature of compatibility with that of the curing temperature.


The powder application is a functionality in way of many variations. There are two basic techniques used in this regard


1) Fluidised bed, and,


2) Electrostatic spray.


The technique of fluidised bed explained


The fluidised bed technique is referred to as the original powder coating technique, too. It is still regarded as the main technique used with respect to the application of thermoplastic powders. The fluidised bed technique is employed for the application of some thermoset powders. This technique is used as it pertains to the latter where a high film construction or build is the requisite. Thermoset powders designed for electrical insulation frequently make use of the fluidised bed technique. The parts used in the process are preheated to a relative temperature higher than the powder's melting point. The parts are then immersed into a fluidised bed of the powder and the plastic powder, subsequently is melted onto the part.


The electrostatic spray technique explained


The electrostatic spray is the technique employed for thermoset powders. The particles of powder are provided with an electrical charge within the coating gun. The targeted part is attached to a grounded fixture. The powder particles, electrically charged, are attracted to the ground part and attach themselves to the part like magnets. The particles continue to build up on the surface area of the part. The buildup of particles results in the part being covered by the charged particles. Once total coverage of the part by way of the charged particles is achieved, the extra particles are repelled by the charged particles covering the surface and the process comes to a halt. The process provides a nice even thickness with regard to the film.


Proper coating of particular parts, within the manufacturing process is achieved by the way of two processes. The coating adheres nicely, and when applied to the correct part---lasts for many decades. A handy dependable way which to achieve a durable and quality application with regard to covering a part is achieved easily by way of making use of powder coating services.