3.1 - FDA Approved Coatings

FDA Approved Coatings for
Food and Pharmaceutical Equipment
The nature of food and pharmaceutical industries require that strict guidelines be followed in any process affecting its’ manufactured equipment.

Steel Applications
An autocatalytic coating of nickel, commonly referred to as Electroless Nickel, is most often recommended for use on steel parts. A minimum thickness of .001 inches on Electroless Nickel will adequately protect the base metal from corrosion. This coating will resist caustic, sulfate, chloride, and other organic solutions, but nitrates will discolor the surface. Published charts are available that detail how long a particular application will last when submerged in everything from sea water to acetic acid. In addition, Electroless Nickel has excellent lubricity and a Rockwell hardness ranging from 52-60.

Aluminum Applications
An electrochemical process is applied to aluminum alloys, which transforms the surface to aluminum oxide - .001”, both above and below the surface. This Hardcoat Anodizing transforms the soft aluminum into a wear and corrosion resistant medium, attaining a Rockwell hardness of 48-54. Like electroless nickel, hardcoat anodizing also has excellent lubricity, but it also can be dyed an attractive jet black.

Choosing a proper aluminum alloy prior to manufacturing will allow for determination of the eventual thickness, corrosion resistance, and color of the alloy, since every alloy responds differently to the hardcoat process. For example, a 1050A alloy would exhibit the highest response characteristics, and a 6061 just beyond that, but a 2014 or 360 would not achieve a high degree of long-lasting properties.

Harsh caustic or highly acidic solutions will eventually disintegrate a hardcoat part, requiring that highly trained and highly knowledgeable personnel understand that concentrated solutions are not always superior in a maintenance wash down, but rather that mild detergents in warm water will extend the longevity of the coating.

Teflon
A registered trademark of the DuPont company, Teflon is really a material commonly known as polytetra-floroethylene or PTFE. Teflon is used after the electroless nickel or hardcoat anodizing process in order to increase a parts release properties. After a teflon application, a part will feel slick to the touch, and will exhibit a low coefficient of friction. Thereby, parts used in high-stress environments such as bending or sliding require the Teflon coating. PTFE is a clear substance that cannot be visually detected, since it will merely reflect the color of the base coating.

Tin
For many years, tin has been a popular choice in the food handling and processing industry. Parts made of cast iron are usually tin-coated because it is non-toxic and offers exceptional resistance to strong acids or alkaline cleaners. Tin is, however, a soft material which exhibits limited wear resistance during continuous use, poor lubricity properties, and a tendency to discolor or tarnish with age. While tin is still used today, it is becoming more and more apparent that electroless nickel and hardcoat are preferred alternatives.

Stainless Steel
Despite its costs, stainless steel is still the “miracle-metal” used primarily for sanitary reasons and corrosion reduction. Stainless steel is really just ordinary steel blended with 8-12% nickel content, which results in improved hardness throughout the alloy. Normally, no coating is needed after manufacturing stainless steel products, however, it may require passivation to remove traces of iron embedded at the surface, which can ultimately result in a rusted-looking part. Passivating actually cleans the surface of all metallic impurities, making it an essential part of the stainless manufacturing cycle.

For additional details on these processes, call us and we’ll be happy to run samples or schedule a visit at your convenience.

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