Manufacturers that require same-day black finishing of small lots of aluminum parts can blacken parts in-house and achieve a durable, satin-black finish using the mini BK-LC line, according to manufacturer Birchwood Casey. The Lumiclad process utilizes a simple dip-tank procedure to form a durable, black-oxide coating on aluminum. One heated tank is used in the process line, and it does not require electrolytic current. The process is said to work well on virtually all cast and wrought aluminum alloys, and it forms a smooth, black finish that tightly adheres to the aluminum substrate with no rub-off.
The 1.5-µm-thick finish does not shrink hole diameters or add measurable thickness, the company says, adding that part dimensions are easily maintained. Designed primarily for indoor applications, the finish features an inherent lubricity that aids in assembly and break-in of mating surfaces. This combination of properties makes it especially useful for pistons, valves, machine components, tooling, fixturing or other precision machined components, the company says.
The finishing process takes 30 minutes for most alloys, eliminating the lengthy turnaround times and high costs of outside finishing, the company says. In-process inventory levels can be reduced because parts can be blackened on a just-in-time basis. The 20-square-foot line is said to fit almost anywhere in a plant.