AUTOMATIC TESTING IN TELEPHONE MANUFACTURE 1133 



that will facilitate feed automatic testing. This requires the cooperation of 

 the product design and product manufacturing interests. It is almost 

 axiomatic that automation in manufacture requires special consideration 

 in product design. Automatic testing imposes the same requirement. A 

 notch or a lug may be needed for proper use of automatic feed devices, 

 or terminals may have to be properly chosen. Again, the method of trans- 

 port from the previous operation needs to be studied, rationalized, and 

 fully agreed upon. If continuous conveyor transportation can be justified, 

 so much the better. In the consideration of conveyor feed, the need for 

 time flexibility must not be overlooked. It is important that provision be 

 made for easy storage of product whenever the test machine is inopera- 

 tive, lest a breakdown of this machine shut down the entire line. 



7. Arrangement of the events in the operating cycle in such a way that 

 their sequence is reliably self determined . This is comparatively straight- 

 forward when the programming is done by gear driven cams or other 

 mechanical means. It requires care when switching logic is used. Switch- 

 ing engineers are familiar with the phenomena known as "relay races" 

 and "sneak circuits." These have psychophysical analogies wherever 

 humans and machines work together. The prevention of both the switch- 

 ing errors and their analogs is essential in automatic test set design. Inter- 

 locks must be provided against any conceivable mishap. 



8. Enough margin and design flexibility in electrical and mechanical 

 parameters to cope with reasonable variations in product design. Improve- 

 ments are constantly being made in telephone apparatus and equipment, 

 and these occasionally result in major redesigns or in entirely new sys- 

 tems. Also the need for adding new features to a historical complex of 

 existing telephone plant causes the generation of an endless variety of 

 special equipments. The product designer needs as much freedom as we 

 can afford. There has to be enough flexibility in the costly automatic 

 test sets to permit adaptation as new designs of product come along. 



These considerations are in addition to the fundamental matters of 

 personnel safety and comfort, motion economy, quietness and appear- 

 ance. 



While dealing with general considerations we must recognize one im- 

 portant difference between the product design and the facilities design 

 problems. In product design there is a premium on optimization of pa- 

 rameters, or striving toward perfection. There is generally also oppor- 

 tunity for winning this premium on later tries even though the rush for 

 first production may have denied it to us in the original design. In facili- 

 ties design there is no such premium and frequently no such opportunity. 

 While careful design is very important, the real premium here is on a 



