Development of Systems of Mechanized Assembly

Abstract

It is pointed out that the radio-making machine of John Sargrove and the serigraphic methods of Brunetti and Khouri have repeatedly stimulated product engineering since 1946. The Sargrove method is briefly described. The early work of Snyder on printed wiring is discussed, and a unitized telemetering channel assembly -- of 1947 vintage - is shown. The author poses the complex question of whether to stock parts, assemblies, or complete units -- a prerequisite aspect to mechanized design which yet remains unanswered in both military and civilian electronics. As a general approach, however, a unitized type of construction is described as having a considerable long-range validity in terms of servicing, transferring of heat, and ease of sub-assembling. The early work by Danko on dip soldering is mentioned, and hot-peel strength data for foilclad laminates is presented. Early work on the printed wiring socket is outlined, and the flexible printed circuit shown at the 1951 IRE National Convention is reviewed. Attention is giveh to a study using limited printed wiring, and standard art and practices, as sponsored by the Wright Air Development Center. Using a transformer coupled intercomm as a vehicle, a common module was chosen -- fixed in cross section but graduated stepwise in length, so the component parts could be stacked. A wrap-around flexible circuit was designed which was adaptable to automation using a cam-operated multihead soldering machine. A mechanical lock of the component parts before soldering, and the importance of accessibility are stressed in the development. The paper is concluded with a series of curves on rejection percentages and on variables controlling printed circuits. A plea is made for the establishment of standard practices -- a role already begun by Various RETMA committees.