Brass Investment Castings – Attractive for Many Reasons
I was asked to think of a valve and describe it, I would be torn between picking one of two images that pop into my head. I’m picturing a metal spigot with a waffley-shaped handle that spins around a central axis. It’s the kind of valve that I connect to a garden hose to water my lawn. The other image that comes to mind is the kind of valve that I saw frequently in mechanical rooms when I worked as a janitor in college. These valves feature a long, slender, rectangular handle that has an axis of motion of about 90 degrees either clockwise or counter-clockwise. Both valves are and do basically the same thing, but they also have another quality in common.
They are both likely brass investment castings. A brass investment casting is a piece of equipment that is composed of brass and that was created by the investment casting process. The investment casting process involves creating a wax pattern, coating that pattern in a ceramic slurry, removing the wax from the ceramic after it hardens and then pouring molten metal into the ceramic shell. The ceramic shell then gets broken, and the metal inside is revealed to have taken the shape of the original wax pattern. In the case of the valves I mentioned, the molten metal was brass. Brass is chosen as a valve construction material because of brass’s smoothness. This is why brass is also often chosen as a construction material for door knobs, bearings, gears and other equipment where low-friction materials are required.
Because brass is composed primarily of copper, it is an inherently suitable material for the investment casting process. Also, in addition to being a highly-function material, brass is also considered to be an attractive material because of its shininess. This makes it suitable for castings for decorative purposes. Brass investment castings are in demand for many reasons.