Whenever we are called to troubleshoot a finishing problem the culprit often times turns out to be in the manufacturing process. Typically, these problems can be narrowed down to few different areas of the process such as Laser Cutting, Machining Lubricants or the type of Anti-Spatter.Laser Cutting – Assist Gases
Oxygen is the most commonly used gas for mild steel cutting. Oxygen causes an exothermic reaction and the heat aids in the cutting process. The downside to this is that the heat produced also creates an oxidation on the freshly cut edge which will prevent proper adhesion during the finishing process.
Shop Air (Compressed Air) is worth looking at. It does not produce the same heat, therefore oxidation, on the edges of the part and is of course more readily available without much modification. It must be properly sized and filtered for the application, however, this is often a small thing to do for the benefits.
Nitrogen offers a very clean cut without oxidation as there is no heat, it serves only to remove the molten metal. Nitrogen works very well with stainless steel and aluminum, it can also cut mild steel much faster than oxygen on light gauge metal. Nitrogen is the slowest assist gas and for this reason, is typically only used where surface quality is important.Laser Cutting – Oxide Edge Removal
There are some cases where it doesn’t make sense, or you cannot, change the laser cutting process at the beginning and must make provisions afterwards. In cases where there is no choice but to deal with the oxide edges left behind, there are really only two viable options available; mechanical removal or chemical pretreatment.
Mechanical Removal is achieved by either grit blasting the material or running it through a “belt sander” of sorts to remove oxide film. Both of these processes often prove to be too labor intensive for most shops. There are time saving alternatives available that have been developed for just these instances, you can contact us at www.buyritefinishing.com or 888-647-9929 to inquire about these options.
Chemical Pretreatment, or acid pickling, is the only other known method of removing laser scale but just like the above solutions has it’s own set of challenges (washer construction, tighter EPA regulations, greater amount of sludge, waste disposal, etc).
Both of the above methods can be specific to your operation or material. With this being said, it is always a good idea to do plenty of testing to determine the best method for you.
Machine Oils, Lubricants & Anti-Spatter
Many lubricants used in manufacturing processes have Parafinn Waxes or other insoluble ingredients in them. Specifically Parafinn Wax is commonly used as a binder for other viscous type solutions. It is stable and unaffected by most chemical agents which makes it an excellent binder for this application. This is often times an excellent choice for the manufacturing process but not a good choice to be carried into your finishing operation. Parafinn Wax is an organic compound that will reject almost any type of finish just like silicone (we all know how bad silicone is around a finishing operation)! The fact that it is invisible to the naked eye can make it a very frustrating issue to fight as it will commonly creep back out in the dryoff oven or, worse, the cure oven.
Another commonly found culprit is Anti-Spatter. A good Anti-Spatter is formulated to be used only as that, Anti-Spatter, and will often work well with subsequent finishing operations. Often times, however, machine lubricants or oils are used for this purpose and can create problems (see above). Contact us at www.buyritefinishing.com OR 888-647-9929 to find out more about choosing a good Anti-Spatter for use with your powder coating operation.