20. The Profile Graph


Trying to understand surface texture using just a parameter or two is like trying to drive at night using only your speedometer and a compass. Those tools can tell you which direction you’re headed, and how fast…but they can’t help you to correct.

The situation is the same in the world of surfaces: a number (like Ra, average roughness) may tell you that something has changed in your process, but it doesn’t tell you what to do about it. The profile graph is the picture that tells you what’s going on in a process—just like looking out the windshield of your car.

In this video we describe the profile graph and dive into what it can tell us about our surfaces and processes. Rather than “dead reckoning” suing a parameter or two, you can use the profile graph to relate the shape of your surface to what’s happening in your process.