There has been no technique for evaluating or measuring the fit of components until today. Parts have not been developed to fit their intended mating surfaces and no defined method exists for assuring that these fits remain consistent. Design verification and production validation could not be confirmed until the beginning of production while coordinating fits between components was normally ignored. As a result interface contact performance minimums within joints could not be assured so failures from internal stresses or insufficient contact (bond) would result.The following surface match technique provides joint design and development control capabilities necessary for removing the unknowns from joint design and manufacturing. The technique provides insights and controls necessary to achieve reliable joint performance with control starting at the design prototype development phase and continuing through to ongoing quality control.Designers, Mechanical and Process Engineers, as well as Quality Control people have all experienced joint design and assembly problems. Voids or interferences from the mis-match of joint surfaces have effected joints reducing strength, creating unnecessary stresses, and making assembly difficult. These conditions have also promoted corrosion and caused pre-mature failuresAt Chrysler we knew that joint failures were resulting from these mis-match or assembly mis-alignment conditions but we had no means of evaluating the problem. In addition because these fit problems could not be observed they could not be analyzed or avoided. To assure reliability from any joined surface application Chrysler knew these mis-matches or mis-alignment conditions had to be controlled (Illustration #1).