Different Methods for Industrial Coating Removal
Surface finishing industry professionals know the importance of having hooks, fixtures, and metallic parts that are 100% clean before the coating process begins. When they are covered in layers of paint and powder, the number of defective or rejected parts could increase. Ultimately, this could cost plants money, time, and resources. Thermal and chemical stripping are two effective methods of removing paint layers.
Coating removal is a vital step of the industrial process; it fully removes coating layers from the surface of a hook, fixture, or rack. In addition to improving the physical appearance of the structure, removing built-up coating from metal hooks and fixtures is also needed for chemical and electrostatic reasons.
In order for powder coating and paint materials to completely stick to the metal surface it is supposed to cover, there needs to be a strong electrical connection between the part and the coating. This is known as grounding, the process of removing excess static charge from an object by providing a conductive pathway, neutralizing charged objects. Hooks, fixtures, and racks should be properly grounded to allow for a pathway to form.
However, when there are many layers of paints on the material, insulating polymers prevent electrons from flowing freely, reducing overall grounding, quality, and effectiveness of the coating process.
When metal hooks are properly cleaned, the grounding is improved which directly improves transfer efficiency and reduces defects.
There are several methods of coating removal and paint stripping you can choose from. While each will achieve the same end goal, the different approaches allow you to select the one that will work best for the specific job at hand.
Two of the main methods of removing coatings from parts are thermal stripping and chemical stripping. By fully understanding these two paint stripping types, you can accurately choose the one that will work best for your purposes.
Thermal stripping utilizes high temperatures, usually in the form of burn-off ovens or infrared heating, to strip parts of their coatings. Burn-off ovens, also called pyrolysis ovens, are the most common form of thermal stripping.
This method of paint stripping can be used in any industry, but the most commonly served industrial markets include aerospace, defense, and automotive manufacturing.
When metal parts are heated to a high temperature, the heat softens the coating and then breaks it down to remove the layers of paint without damaging the part. While all models are different, burn-off ovens can reach a temperature as high as 900°F (482°C). This is critical to ensure the layers are soft enough to be removed.
KEY INSIGHT: Not all materials should be put into a burn-off oven for removal. Because they reach such a high temperature, it’s important to ensure that the part you are working with is not sensitive to temperature and can withstand the intense heat.
The parts are then put through cycles. These cycles can vary drastically in time based on the level of heat used. Lower heat could cause cycles that last several hours while much higher temperatures could have cycles that last only minutes. However, cycles are typically four to five hours in length.
Thermal stripping is often the right choice for jobs that might consist of large batches or bigger surfaces and objects. It can remove especially thick and stubborn coating layers. Additionally, because the heating equipment does a lot of the work, minimal labor is involved.
However, there can be cons to this process. One is that the high heat used can possibly distort or damage parts if the substrates are not applied correctly. Also, when used on powder coating hooks, the grounding capability could be effected, leading to lower quality products.
Another factor to consider is that residues can be left behind after treatment which can contribute to a dirty atmosphere. Thermal stripping also involves a high initial investment and usage cost, so it’s important to keep these considerations in mind.
If thermal stripping does not seem like the best option for your operations, consider using chemical stripping. This method uses an industrial-strength chemical solution to dissolve or soften coatings. These chemicals break down the bond that is holding the paint to the surface of the metal. Chemical baths are often used to completely immerse the parts in the chemical solution.
KEY INSIGHT: Don’t forget to rinse! After the parts are removed from the chemical bath, they must be sprayed with high-pressure water jets and treated. This will help avoid defects.
Like thermal stripping, chemical stripping can be used in nearly any industry including automotive, construction, and general manufacturing. Chemical stripping is a popular coating removal method because of its diverse usage and ability to remove a wide range of coatings.
This process can handle high-volume work at lower costs than other methods. Minimal labor is involved throughout as the equipment is self-sufficient. Effective even on complex shapes, it will maintain the integrity of your parts throughout production.
On the other side though, it’s important to keep in mind that the chemicals used can be harmful and dangerous to the health and safety of employees. Be sure to implement appropriate protocols and regulations.
While thermal stripping is known for stripping parts of all sizes, chemical baths are limited by their size. Additionally, this can be a messy process that might not be the best choice for all environments or plants.
When it comes to removing coatings on parts, don’t procrastinate. Having high-quality parts free of ash, residues, and unnecessary layers will improve production.
Both thermal and chemical stripping can be incredibly useful, but it’s wise to keep in mind the exact specifications and jobs you are working with to make the best choice for your operations. With a better overview of which is best for which functions, you will be able to make an educated decision.
Whether you are electing to use thermal stripping or chemical stripping, DuBois’ technical experts are here to help you achieve the best result possible.
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