As with parts that undergo hot-dip zinc, parts must be sized appropriately to allow for the thickness of the coating.ĭavid Zimmermann was president of Pivot Point Inc. This creates a thicker and somewhat irregular coating compared to electroplating. Parts are tumbled in zinc powder, and the peening action of the tumbling embeds powdered zinc into the part’s surface. It also adds a thick, irregular coating, so the size of parts may need to be adjusted to compensate. It leaves a dull grey finish that protects against corrosion. Metal parts are galvanized by being dipped in pure molten zinc. Chromate is typically added to increase corrosion resistance and, if desired, add color. It is one of the most widely used plating finishes, providing an attractive, low-cost finish. Any metal can be electroplated with zinc. It leaves a white to blue-grey finish and costs little to apply. It leaves parts with a charcoal grey or black finish. This low-cost coating combines zinc or manganese phosphate with a rust-inhibiting oil dip. It also produces a passive corrosion-resistant finish. The acid removes iron particles and brightens the finish. This process is carried out by dipping stainless steel parts in nitric acid. If even one were to corrode, it could cause serious issues and Zinc plating helps to avoid that. Screws do more than just hold two items together they also take a lot more physical stress than most people realize. This hard, stable and relatively expensive finish leaves a silver color on all metals and good corrosion protection. More often than not, the Zinc plating technique is used to protect screws and other types of small fasteners.
This coating can also change the color of the fastener to olive drab, green, black, red, blue or bronze finish. If a metal part has been coated with zinc or cadmium, it can also be given a finish of iridite to add even more corrosion protection. This hard, lustrous bright blue or white finish provides wear and corrosion resistance on all metals, but it is expensive. Standard clear chromate leaves a bluish-white hue other colors such as yellow, olive drab and black are also available.Ĭhromium. It increases corrosion resistance and can be colored. This is a secondary dipping process used on zinc or cadmium-plated fasteners. Any metal can be electroplated with cadmium.Ĭhromate. On the downside, the process is costly and potentially hazardous to the environment. It is often used on parts for marine and aviation applications. This bright or dull silver-grey plating gives parts excellent corrosion resistance. Black oxide can only be applied to ferrous fasteners.Ĭadmium. However, parts usually undergo an oil dip after being treated, and it delivers some corrosion resistance. A chemical treatment that gives fasteners a black finish that does not add thickness to parts, nor does it provide corrosion resistance. It can only be used on aluminum.īlack oxide.
It provides good corrosion resistance, and parts can be color dipped after being anodized. An acid dip that gives parts a frosty, etched appearance. 3, 2016.ġ0 Ways to Use the Ubiquitous Retaining RingĪnodizing.
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