Plaforization

Question:

I have read some literature on a process for cleaning parts for powder coat called plaforization. Could you clarify the process as well as give your opinion of the process? Thank you. G. N.

Answer:

I addressed the general aspects of the process in my October 2002 column (with a follow-up in December of the same year) (www.pfonline.com/articles/clinics/1002cl_clean1.html). After reviewing probably much of the same literature you have, I do not feel like I really understand the mechanism behind the process.

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The Plaforization process is described as a single stage, organic phosphate coating. Maybe it is my understanding of the traditional phosphating process, but details and mechanisms of this process seem counter intuitive. For instance:

• In traditional phosphating, the part is often cleaned of oils in a separate degreas- ing stage followed by rinsing. The organic phosphate process is said to “chemically capture” the oil up to 14 grams per 100 sq ft of material processed. I am not sure how this is supposed to work since they also say that it remains “trapped” through the paint curing process.
• The dedicated cleaning step of a phosphating process can generally han- dle a wide variety of different soils from different sources. The Plaforization process cannot tolerate water (since it is an organic process), so water-based or water-diluted lubricants are not accept- able unless dry. This could create prob- lems or additional steps in manufacturing. Additionally, the organic phosphating process does not handle stearate and lubricants with acidic additive. Although not acidic upon addition, extreme pres- sure additives to lubricants react with the base metal under the temperature and pressure of metalforming to produce an acid.
• In traditional phosphating, the process is initiated by the acid attacking the base metal that raises the pH at the metal/ liquid interface. The iron or zinc phosphate is not soluble at that pH which results in precipitation and formation of the coating at the surface. The crystal structure can be viewed with a micro- scope. An SEM is especially useful to capture the depth of field created by the phosphate coating. The mechanism of the organic phosphate is not clear. It also does not produce a phosphate crystal structure that can be viewed under magnification.

I don’t like to provide opinions about specific products in this column, especially in a case where there is little specific information on the actual mechanism of the system.