When it comes to coatings, the amount of surface area matters. We know that increasing the surface area can improve adhesion, and that “roughing up” a surface increases surface area. But is all “roughness” equal when it comes to making coatings stick? Surface area Surface area impacts how well a coating will adhere, how well … Read more
Abrasive wear can greatly impact the performance of engines and machinery. This kind of wear can be caused by excessive roughness on either of the contacting surfaces. However, just looking at roughness may not give you the complete story. When we define roughness, we typically exclude longer spatial wavelength structures that may also advance wear. … Read more
Michigan metrology has been gathering and sharing information on surface roughness, texture, and tribology for almost thirty years.
We tend to think of “new” surfaces as shiny and smooth, and “worn” surfaces as rough, dull, or uneven. But for a bearing surface, the opposite is often true: the initial, manufactured surface, with its carefully controlled texture, may become smooth and shiny over time…and that may not be good news at all. The way … Read more
A lot of effort goes into creating materials that can resist sticking, repel water, or keep oils off of cell phone screens. But some plants are able to accomplish tasks like these naturally. In this post we look at one amazing example…but first, a crash course in surface energy and surface wetting. Surface energy and … Read more
We’ve had a lot going on related to ice lately! It is that time of year… A few months ago, we posted an article about the sport of curling, which is fascinating from a surface roughness perspective. This month we had a chance to talk to Russell Frank, who is leading up the Curling Ice … Read more
For surface roughness measurement, it would seem like “non-contact” methods would always be preferable. After all, being able to measure a surface with no possibility of contact damage would always be appealing…right? As usual, the actual answer is a little more complex. When non-contact is preferable Non-contact measurements are typically made using optical methods such … Read more
Cutoffs define the band of spatial wavelengths that will be included in the calculation of surface texture parameters. Per specifications, the cutoffs must be specified. So, what do you do if they aren’t?
Ra, the roughness average (or average roughness), is the average of the surface heights along a measurement trace. Sa is the average roughness over a measurement area. Can we calculate Sa by averaging the Ra of every trace across an areal measurement? The answer is: no. Here’s why. Calculating Ra As a refresher, to calculate … Read more
Some paint finishes are purposefully glossy or shiny. Others appear matte, or dull, or hazy. So, what leads to the difference…and what do all these terms really mean? Texture scatters light A perfectly smooth surface reflects light completely. If the light source is a collimated laser at 45 degrees incidence, it will reflect off the … Read more