Our Process

The powder coating process involves three basic steps: part preparation or the pre-treatment, the powder application, and curing. 

Part preparation processes and equipment

Removal of oil, dirt, lubrication greases, metal oxides, welding scale etc. is essential prior to the powder coating process. It can be done by a variety of chemical and mechanical methods. The selection of the method depends on the size and the material of the part to be powder coated, the type of impurities to be removed and the performance requirement of the finished product.

Another method of preparing the surface prior to coating is known as abrasive blasting or media blasting and shot blasting. Blast media and blasting abrasives are used to provide surface texturing and preparation, etching, finishing, and de-greasing for products made of Steel, stainless steel, aluminum, fiber glass, and cast iron*. The most important properties to consider are chemical composition and density; particle shape and size; and impact resistance. 

Powder coating can also be removed by a burning off process, in which parts are put into a large high-temperature oven with temperatures typically reaching an air temperature of 300–450 °C. The process takes about four hours and requires the parts to be cleaned completely and re-powder coated. Parts made with a thinner-gauge material need to be burned off at a lower temperature to prevent the material from warping.

* Cast aluminum and magnesium parts may experience an out-gassing and/or bubbling in the finished powder coat. We will take every precaution to avoid out-gassing, however we can't be held responsible for bubbling caused by porous castings.

Powder Application

The most common way of applying the powder coating to metal objects is to spray the powder using an electrostatic gun, or corona gun. The gun imparts a negative charge to the powder, which is then sprayed towards the grounded object by mechanical or compressed air spraying and then accelerated toward the work-piece by the powerful electrostatic charge. There is a wide variety of spray nozzles available for use in electrostatic coating. The type of nozzle used will depend on the shape of the work-piece to be painted and the consistency of the paint. The object is then heated, and the powder melts into a uniform film, and is then cooled to form a hard coating. It is also common to heat the metal first and then spray the powder onto the hot substrate. Preheating can help to achieve a more uniform finish but can also create other problems, such as runs caused by excess powder.

Because powder coating does not have a liquid carrier, it can produce thicker coatings than conventional liquid coatings without running or sagging, and powder coating produces minimal appearance differences between horizontally coated surfaces and vertically coated surfaces. Because no carrier fluid evaporates away, the coating process emits few volatile organic compounds(VOC). 

Curing

Most powder coatings have a particle thickness in the range of 2 to 50 μm, a softening temperature Tg around 176°F, a melting temperature around 300°F, and are cured at around 400°F for a minimum of 10 minutes to 15 minutes (exact temperatures and times may depend on the thickness of the item being coated).[3]For such powder coatings, film build-ups of greater than 50 μm may be required to obtain an acceptably smooth film. The surface texture which is considered desirable or acceptable depends on the end product. Many manufacturers prefer to have a certain degree of orange peel since it helps to hide metal defects that have occurred during manufacture, and the resulting coating is less prone to showing fingerprints.