In the field of precision manufacturing, an indicator that is invisible to the naked eye is determining the success or failure of products worth billions of dollars - surface roughness. According to the calculations of the National Institute of Standards and Technology (NIST), the failure of mechanical components caused by uncontrolled surface roughness causes more than $18 billion in losses to the global manufacturing industry each year. From titanium alloy joints implanted in the human body (Ra < 0.1μm) to the sealing surface of satellite thrusters (Ra 0.4-0.8μm), the difference in micro-texture directly affects key performance such as friction coefficient and fatigue life. This article will deeply analyze the scientific connotation and industrial value of this "invisible quality indicator".