Powder coating is a finishing process that makes use of thermoplastic and/or thermoset material for the objective of applying coating to the surface area of either glass, metal parts, plastics and medium density finderboard.
The cleaning and preparation of parts is normally done with fine powder that covers the surface of the parts that are worked on, and then the final touch is placing the parts in an oven for heating. This last step enables the powder to simmer deep into the part and form perfect coating.
The craft of power coating is used in various industries like the consumer product industry, construction and the appliances industry. Institutions like schools also utilise this service in a sense that school desk manufacturing relies heavily on powder coating for durability.
Even at an individual level, one can powder coat rusted furniture, frames, car rims, gates etc.
As you can imagine, it can be a bit of a technical process and it requires a certain level of expertise to get right. In this short article, we will go through the step-by-step journey in getting power coating right.
The first step that begins the entire process is pretreatment. Before coating is applied to a part, cleaning must be done vigorously. A typical procedure of cleaning usually includes aqueous cleaning, vapour decreasing and/or ultrasonic cleaning. In an instance whereby a part will require organic coating, great emphasis is placed on surface pretreatment.
Proper cleaning of the metal part is crucial in ensuring that it is well prepared for dry-off. Great consideration is also taken to avoid contamination, specifically soil particles and other forms of dust that may land on the surface area.
In terms of application, it is important to remember that powder coating subscribes to two methods. These methods determine the kind of coating that needs to be done on a specific part for the paint’s durability, and in arriving at the decision of what needs to be applied, factors such as application environment, sizing, substrate materials and cost are considered.
Electrostatic spray deposition (ESD) and Fluidized bed application are two components of powder coating, and they work, ideally, for multi step surface finishing for metal and non-metal substrates.
In application, technicians employ either one of these (depending on the part they’re working on) and make use of a spray gun and spray booth.
The curing phase in the powder coating process is characterized by the method of application. Remember, we have Electrostatic spray deposition (ESD) and Fluidized bed application. Out of these two, you get curing ESD coated parts and curing fluidized bed coated parts.
3.1. Curing ESD parts – for all those parts that undergo ESD powder coating, a suitable method of curing is the oven, with the temperature averaging between 162 and 232 degrees celsius. Special attention is paid to the shape, size and thickness of the metal part in regards to the temperature that is applied in the curing. The time spent in the oven varies for each part in relation to its size. These can range anywhere from 10 minutes all the way to an hour and beyond.
3.2. Curing fluidized bed coated parts – fluidized bed powder coating is the phase of taking a part and dipping it in a pot of fluidized powder. The part can either be dipped like this or it can also be fluidized electrically by moving it over a cloud of powder with the pot of fluidized powder resting on the base.
For both techniques, preheating plays a vital role. It’s the catalyst that ensures the thorough blending of coating into the preheated part, with particles melting seamlessly into the object.
Whether you’re a professional, semi-experienced or entry-level operator, quality powder coating remains a craft that requires continuous practice and dedication in order to get right. The beauty and reward of the job lies in seeing a final product. The amount of time spent on it is an amazing demonstration of what happens when science meets art.