Four essential features are generally required of any form of transportation : Speed, safety, comfort and economy. The airplane must compete with other forms of transportation and with other airplanes. The greater speed of aircraft travel justifies a certain increase in cost. The newer transport airplanes are comparable with, if not superior to, other means of transportation. Safety is of special importance, and improvement in this direction demands the airplane designer's best efforts.

The rapidly extending employment in many industries of cold pressing and stamping operations in the production from sheet metal of a great variety of components, embracing both simple and very complex shapes, renders cold pressing an extremely suitable subject at the present time for a joint discussion by a group of technical societies representing a wide range of industries. The particular interests of these industries naturally vary widely, both as regards type of production and the materials employed, but there should exist many basic problems common to all.

The process of cold pressing can only be applied to the more ductile metals, and the greater part of the material so treated is in the form of thin sheets. Leaving out of account such exceptional materials as lead, a ductile metal is appreciably hardened in the process, losing some of its ductility and having its “elastic limit” raised. It can be restored more or less completely by annealing, according to the temperature and the time of treatment. In addition, changes in ductility may occur in course of time, even at atmospheric temperatures.

In deep-drawing operations connected with mass production the question of the reduction that can be obtained in a single draw without causing excessive waste is of considerable importance. This drawing capacity (maximum draw) has, as will be obvious from Fig. i, proved capable of very considerable increase in the course of the last decade.