The pretreatment process is a vital part of every finishing procedure looking to achieve a specific requirement on an end result/finish product. A pretreatment system is a chemical application for your metal surfaces that allows for better bonding/properly adhere to the surface for coating a surface with paint, powder coat, anodizing, and passivation. It’s a very large contributor to the quality of your product’s final, finished appearance, and longevity. We offer a number of water pretreatment systems that will allow you to effectively and professionally perform pretreatment for your finishing in-house, including the following.
Citric Acid Process
Most people are familiar with citric acid. You’ll recognize it as the primary acid found in oranges and related citrus fruits, as well as food and beverage products that contain them. Pretreating the surface would be required before a citric process. The surface must be clean and oil/dirt-free. Citric acid is a somewhat newer method of passivation relative to nitric acid systems. Much safer, easier to maintain, and lower equipment cost.
There are many advantages to citric acid passivation. For one, citric acid is a relatively benign acid that reacts well with iron and does not clash with elements in stainless steel alloy. This process can extract iron without damaging stainless steel’s inherent alloy. In addition, it allows for fewer environmental concerns related to the disposal of its waste, since citric acid is entirely organic. Citric acid passivation is healthier and safer for those involved in the passivation process. You should also find that citric passivation is easy to perform with our machines, provided your workers are sure to clean off any oil, grease, coolant, dust or other contaminants prior to treating stainless steel.
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Fluorescent Penetrant Inspection (FPI)
FPI is a way of locating cracks and other defects in metal, ceramic or plastic. The process works by allowing a fluid with low surface tension to penetrate into the surface, then adding a developer that draws the penetrant out, highlighting the area of surface defection when UV light is applied. We offer fully automated precleaning/semi-automated FPI as well as fully automated dye penetrant systems.
The Nitric Acid Process
The nitric acid process is essentially the same as the citric acid process — that is to say, passivation. The distinction is that nitric acid is a mineral acid, not an organic one. Nitric acid is highly effective, so much so that it’s the most common acid used in passivation and is often used for sensitive finishing jobs such as those for precision aerospace components. However, since it is not organic, it does present some waste disposal issues with respect to the environment that are important to address. Machinery and safety concerns with use. Plastic tank system or UHMW liner for stainless tanks a must.
The nitric acid passivation process includes five stages: wash, rinse, passivation via nitric acid, rinse, hot air blowoff drying. The drying phase at the end features hot air at 150 degrees Fahrenheit so that components dry rapidly and with maximum evaporation.
The manufacturing and finishing of parts should include measures to prevent corrosion and other degradation. Passivation is the process of adding a protective layer to the exterior of a piece that shields it from corrosion. Naturally, there are different approaches to passivation for different types of material, including the nitric acid process and the citric acid process.
In more scientific terms, passivation is the chemical dissolution of exogenous iron or iron compounds from the surface of stainless steel. When a component part is submerged in an acid bath, either nitric or citric acid dissolves the surface iron and enhances the formation of more chromium oxide, which is what gives stainless steel its ability to resist corrosion. This process removes any iron ions/corrosion on the surface prior to being used in an application. All food-grade stainless steel has to be passivated or it could get rust spots once the device starts being used and comes in contact with water.
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We are committed to delivering outstanding services that deliver both efficiency and cost savings for our customers. Whether you need the use of a passivation machine or fluorescent penetrant inspection equipment, we deliver the machines and the processes you require. Some of our clients are experienced in the industry and have a firm vision of what they need. Others are new to the industry and have basic questions. No matter your experience level or needs, the team at Advanced Deburring & Finishing can help.
Contact us today about the use of a passivation machine or fluorescent penetrant inspection equipment.