Low temperature black chrome (LTBC) plating is a special coating used for many different products such as shafting, linear guides, and actuators. This popular coating is beneficial in many ways. First, let’s review what it is. Basically, low-temperature black chrome is a ceramic-infused fluoropolymer based plating solution applied at below zero degrees Celsius, which is suitable for loaded rolling element contact. Through the plating process, an alloy-like diffusion layer is formed at the outer margin of the part, allowing particles to completely integrate the base material and create an inseparable bond.
In other words, black chrome plating is a polymer based coating “cooked” into metal such as carbon and embeds deeply into the material. Since it is a polymer, LTBC is flexible. Many rolling elements require that flexibility in the part so that the metallic coating doesn’t flake off. Over time deflection occurs in the part causing the metallic coating flake off with LTBC, it does not. The advantage here is that you can see the wear as the metallic subsurface starts to shine through the black chrome plating. It also does not affect the hardness of the component material nor does it assist with lubricity.
Typical application use for black chrome plating are food, medical, electronic assembly and semiconductor. For food applications, there is typically a caustic wash down — the LTBC plating will protect the components from corrosion. It is great for many delicate applications that are sensitive to contaminates. Even the color has an aesthetic advantage, as rust has an ugly appearance especially for medical applications. Rust will signify weak and old to customers, and LTBC plating will not appear that way at all as it is a rust preventative coating. With shiny metallic coatings, light reflects from the component easily, which is a big disadvantage for optical applications like camera positioning or with laser measuring.
A common misconception is to use 440C stainless steel as stainless steel will never rust, but over time it will. It all, of course, depends on your application and requirements but our testing shows that after 168 hours of salt spray 440C stainless steel does rust. This is due to the heavy carbon content in this metal. While 440C stainless steel does last longer than plain 52100 carbon steel, it is evident that LTBC out lasts both materials, a clear winner.
There are a variety of products that MISUMI carries with LTBC plating and thickness varies on the component. For example, linear shafting will have 1-2 microns of LTBC plating, linear guides will have a 5 micron (0.005mm) thickness as well as linear bushings. Linear guides will have LTBC plating on the rails and blocks. These numbers are so small that depending on your application, it may not affect tolerancing at all. As mentioned previously, the advantage of LTBC plating is the color and seeing the metallic subsurface show after wear. This will indicate that it may be time to replace the part. It is important to note that depending on your application, especially on shafting, it is acceptable to see different shades of LTBC plating and wear. With plain metallic chrome plating, it has the same appearance as the polished carbon steel component so you would not see wear until oxidation begins to occur, not exactly a pretty sight to see in your machine or components! This coating can last in some applications for up to 10 years or even more. It is also great for high humidity applications — we tested with conditions at 95% humidity, 70 degrees Fahrenheit and exposed at 1000 hours, and the LTBC plating still had no signs of corrosion.
It is evident that LTBC plating has many benefits to consider and MISUMI has many offerings in components from ball screws to washers. You can even search our website with the terms “Low Temperature Black Chrome” and the results will show you the components we have available.
We encourage you to test it out in your application! If you have any questions, please feel free to comment below or email our engineering team at firstname.lastname@example.org.