subject: Numerically Controlled Machines [print this page] Besides developments in the areas already mentioned the need for reduced cost and lead time and high quality led to the introduction of quality engineering approaches to product design. Notable among these is the Taguchi method of product design, which introduced the concept of loss function and signal-to-noise ratio for product design. Material requirements planning and manufacturing resource planning, just-in-time manufacturing philosophy, group technology, and cellular manufacturing led to significant changes in the way production is now planned and controlled at the shop floor.