Understanding how rough is rough

Surface Profiler is a completely free package of software and theory that I wrote to help understand the meaning of "Roughness" via surface profiles.

Background

It is so easy to measure surface roughness with modern equipment. But what do Ra or Rz really mean? And how do they relate (if at all!) to the functional requirements of your surface? If you ship your product to a customer and it's in spec for Ra is it still in spec for the customer's application? Maybe one of the many other roughness parameters would be a better measure for your customer. But which one? In other words, How Rough is Rough?

SurfaceProfiler

The package lets you explore a set of test surfaces of very different characteristics - sharp peaks, deep valleys, smooth waves etc. You can then see "live" how well (or badly) different measures can distinguish between them. For example, Rz will give you exactly the same number for a surface with sharp peaks and one with deep valleys. So what measure can reliably tell the difference? The package lets you find out for yourself. But there's a large Help file to guide you through the process.

For each artificial surface you can add noise and/or baseline slopes so you can see how those will interfere with your measurements.

Finally, the package lets you import a real surface profile (provided it is in the correct, simple format) if your equipment allows you to export the raw data. My "rule" is "Never measure a surface profile on equipment that doesn't provide a digital output of the data". Why? It's not because I sell expensive surface profilers (I have no connections to the industry), but because my own real-world experience has shown time and time again that relying on just the Ra, Rz... numbers from the equipment meant that I lost a lot of insights into what was really going on.

These issues are discussed in greater detail in my article in GalvanoTechnik: How Rough is Rough? Galvanotechnik, 101 (2010)12, S. 2751-2754".

Access to the package

To explore SurfaceProfiler the minimum requirement is to download SurfaceProfiler.zip which you simply unzip into a convenient folder to be up and running - provided that the Microsoft DotNet Framework 4.x (freely available from Microsoft) is installed on your PC. The most recent version (Jan 2012) is v2.0.09 which fixes a number of minor glitches,adds an extra "spike" option and also includes a "Length Ratio" calculation explained in the Help file.

The Help file provided with the package contains a simple explanation of Surface Profile theory and can be downloaded as SurfaceProfiler.rtf

Why is it free?

Over the years lots of people in the industry have helped me to understand surface profiles. This is my "thank you" to those people and a chance to give something back to the industry. It's completely free, there are no adverts and its installation is simply the files that you see in the zip file. An earlier version of the software was written when I was at MacDermid Autotype and I thank them for the excellent education in the practical realities of surfaces and for permission to create this new version for free availability.

Please send all feedback/comments to me at steven@stevenabbott.co.uk