In order to stay extremely competitive, LMC has developed a specific phosphating business unit, with it's own team leader that specializes in the phosphating process. Each unit has it's own value stream manager who is trained to utilize LEAN techniques and to create single source responsibility to each customer. This cutting edge thinking is how you get the best quality, deliver and cost for your component.
Phosphate coatings are used on steel parts for corrosion resistance, lubricity, or as a foundation for subsequent coatings or painting. It serves as a conversion coating in which a dilute solution of phosphoric acid, which is applied via spraying or immersion, chemically reacts with the surface of the part being coated to form a layer of insoluble, crystalline phosphates. Phosphate conversion coatings can also be used on aluminium, zinc, cadmium, silver and tin.
Phosphate and oil coatings
Phosphate coatings are porous, so they must be treated with oils or other sealers in order to provide corrosion resistance. P&O (phosphate and oil) coatings are frequently used for this purpose, for lubricity and to prevent galling.
Base for painting and coating
Most phosphate coatings serve as a surface preparation for further coating and/or painting, a function it performs effectively with excellent adhesion and electric isolation. The porosity allows the additional materials to to seep into the phosphate coating and become mechanically interlocked after drying. The dielectric nature will electrically isolate anodic and cathodic areas on the surface of the part, minimizing underfilm corrosion that sometimes occurs at the interface of the paint/coating and the substrate.
The main types of phosphate coatings are manganese, iron and zinc. Manganese phosphates are used both for corrosion resistance and lubricity and are applied only by immersion. Iron phosphates are typically used as a base for further coatings or painting and are applied by immersion or by spraying. Zinc phosphates are used for rust proofing, lubricity (P&O), and as a paint/coating base and can also be applied by immersion or spraying.
The performance of the phosphate coating is significantly dependent on the crystal structure as well as the weight. For example, a microcrystalline structure is usually optimal for corrosion resistance or subsequent painting. A coarse grain structure impregnated with oil, however, may be the most desirable for wear resistance. These factors are controlled by selecting the appropriate phosphate solution, using various additives, and controlling bath temperature, concentration, and phosphating time.
Contact us for your Phosphating needs or to get a quote.
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