Double blade? Triple Blade? Quadruple blade? It's the quest for the perfect shave.

The answer you'll find is at the microscopic level. In a "jerky" motion called stick-slip. Understand this phenomenon. And improve friction performance in your own product or machine design.

Friction is unwanted energy translated into heat. A function of surfaces rubbing under load. If speeds are very low, friction is not constant. Fluctuations can occur. The result is disruption of the most precise, smallest of motions.

Caused by higher static friction ("stick") the initial displacement is deformation. Whiskers are bending, collapsing. Oops, missed cut.

"Slip", on the other hand, refers to low dynamic friction. Displacement is travel and the advancing blade is cutting. But, only after elastic (potential) energy is restored. When the whisker has "snapped back".

That's not a close shave.

So how do you solve "stick-slip"?

The answer is coatings for the lowest possible static coefficient of friction. Materials like polytetrafluoroethylene (PTFE) are ideal, based on their low adhesion energies.

Here's to the perfect shave. And overcoming higher static friction in your own design.