This article explores how optimizing gear design in precision machining reduces crack initiation and propagation. Key aspects include tooth geometry, material selection, and surface treatment processes like carburizing and shot peening. Real-world case studies from companies such as BYD, Boeing, Volkswagen, and Siemens highlight successful applications of these methods in improving gear fatigue life and performance. Crack prediction and monitoring technologies like finite element analysis and ultrasonic testing are also crucial in early detection and prevention. Together, these strategies enhance gear reliability and extend service life in automotive, aerospace, and industrial equipment applications.