Sooner or later, everyone experiences a friction or wear problem. What people choose to do about it is a different matter. You could simply ignore the problem or discard the worn-out device. If that is not an option, then you can replace the part or the entire device with a new one. As an engineer who needs to dig deeper into the problem, you may decide to improve the component design, try a different lubricant, or consider using alternative materials, surface treatments, finishes, or coatings. This book is intended to help those who need to do something about a wear (or friction) problem, whether it involves understanding how it happened, diagnosing the kind of wear that is occurring, developing or using a test to select alternate materials or lubricants, or completing a root cause analysis that could eventually lead to longer product life, improved design, and greater component reliability.