How to Ensure Powder Coats Adhere to Laser-Cut Edges
Have you been receiving reports from clients that the powder coats have been failing on the edges of carbon steel that was cut using a laser? Read on and discover some steps that you can implement in order to prevent this problem from occurring again.
Use an Acid Etch
Carbon steel usually forms an oxide layer when it is cut using a laser. That oxide layer prevents any applied powder coat from adhering effectively. Understanding this chemistry opens the door to remedial measures. The first measure involves selecting an aggressive pre-treatment method that can remove that oxide layer. Acid etches are the best for this purpose because they can react with the oxide layer until it is removed from the edge of the carbon steel product. The powder coat will then have no adhesion problems later on.
Many fabricators prefer to use oxygen as an assist gas during laser cutting because oxygen is more affordable than other options. However, that assist gas reacts with carbon steel during the cutting process. The oxide layer that is formed is a result of that reaction. You can therefore combat the adhesion problem by preventing the oxide layer from forming on the carbon steel edge by using another assist gas. Nitrogen is the best in this case because it won't form an oxide layer on the cut edge. The added cost of using nitrogen as an assist gas can be justified by the time and expense that you would have spent to remove the oxide layer if you had used a cheaper assist gas (oxygen).
Use Physical Abrasion
Another option for removing that oxide layer before powder coating involves using abrasives on the edges of the carbon steel. The specific method that you use will depend on what you have available in your fabrication shop. For instance, wheel abrading can be used if you have the machine. Conversely, the surface can be sanded manually in case you cannot automate that process. However, the manual approach is likely to be time-consuming since the technician has to be cautious to avoid damaging the surrounding parts of the product.
As you can see, adhesion problems can be avoided if you understand the fabrication processes that a product underwent before it was sent to the powder coating booth. The surface preparation process can then be customised to address the specific challenges that are presented by those previous fabrication processes. Consult powder coating experts in case you still get the same problem despite implementing the suggestions above.