Abstract
Concepts of precision engineering design process for optimal design where engineering sciences contribute in the successful good design are elaborated in this paper. Scientific theory and practicality are discussed in this paper. Factors necessary for a complete product or systems design are detailed and application of mathematical design optimization in producing a good design are shown. Many applicable engineering design examples are itemized to show relevancy of the optimal design theory to engineering design. Future trends of optimal design with respect to the 4th industrial revolution of digitization are presented. Paper sets to elaborate that most of the engineering and scientific design problems can be optimized to a good design based on many new/advanced optimization techniques.