Dip Spin vs Rack Spray
In regards to the application of liquid based functional coatings, there are two methods of application in the industry: dip-spin and rack-spray.
Priced per piece, the DECC Company applies functional coatings almost exclusively via a rack-spray process. Whether it be on our electrostatic line, our hand spray line, or in our Research & Development department, almost every part we process is individually hung on a fixture, coated, cured on the fixture and then hand packed into customer dunnage.
Usually priced by the pound, in a dip-spin, bulk application coating process parts are dumped into a perforated basket and immersed into coating. The basket is then raised from the vat and spun at a high RPM, which removes any excess coating with centrifugal force. The parts are cured and the process is repeated as needed depending on the coating recipe or thickness requirements.
Pros and Cons of Dip Spin and Rack Spray
In almost every case, dip-spin pricing is less expensive than a rack-spray price. However, this is true if you take the dip-spin pricing vs the rack-spray pricing at face value only. When taking into account the cost of poor quality (COPQ) of a dip-spin application for certain parts, rack-spray pricing could end up more advantageous in the long run.
Many metal stamping geometries are not suited for a bulk coating application. For example:
- Bends and pockets in the part can result in pooling of coating.
- Thinner gauged metal can bend and distort during processing.
- Certain geometries can tangle together.
- Nearly flat parts can nest, causing coating voids or inconsistent coverage, or become fused together
With all of these issues, a 100% sort could be required after the coating application. In many instances, the sort could yield upwards of 20% fallout, requiring parts to be scrapped or reworked.
Dip-spin is the ideal solution for a vast majority of small to mid-size fasteners or hardware and for numerous metal stamping geometries. In these cases, it would not make sense to pursue a rack-spray application as the benefit would not outweigh the cost. Dip-spin coating has been the gold standard for these types of components and will continue to be in the future.
The DECC Rack Spray Solution
Until recently, even though a dip-spin application would not be ideal for some complex part geometries, it was the only effective way to ensure complete coverage on a component outside of a manual hand-spray, which would be too costly or not feasible on high volume production. As a result, manufacturers would just have to succumb to the fact that they would need to sort, scrap and/or rework their product after the coating application.
To combat this situation for current and potential customers with complex part geometries, DECC has installed two six-axis FANUC robots for touchup purposes on the back end of our electrostatic line. Utilizing this method, DECC is able to coat most of the part with our electrostatic guns and then obtain complete coverage with our robots, ensuring every nook, cranny and crevice of a component is covered.
Contact DECC for Your Rack Spray Processing
Contact DECC today if you are dealing with a quality issue from a dip-spin coating application or if you think your component would be suited for rack-spray processing.