114 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1957 



Scheduling 



Capacity was provided at the Hillside Shop to manufacture a max- 

 imum of 14 repeaters in a calen(hir month. This envisioned 6-day opera- 

 tion with some second and thii'd shift operations; due allowance was 

 made for holidays and vacations, so that the annual rate would be ap- 

 proximately 160 enclosures per year. (An enclosure is either a repeater 

 or an equalizer.) 



Some of the facilities and raw materials were ordered late in 1953. 

 This ordering expanded early in 1954 and continued through 1955 to 

 include parts to be made by outside suppliers and the parts and appara- 

 tus to be made at Hillside. Apparatus designs were not all available at 

 the beginning of the job, and the ultimate quantities required were also 

 subject to sharp change as the project shaped up, thus further compli- 

 cating the scheduling problem. 



Because of the time and economic factors involved, coupled with the 

 developmental nature of the product and processes, one of the most 

 difficult and continuing problems was the balancing of production to 

 meet schedules. For this task, we devised "tree charts" for the apparatus 

 codes and time intervals in each type of repeater or equalizer for each 

 project. Each chart was established from estimates of the time required 

 to accomplish the specified operations and the percentage of good prod- 

 uct each major group of operations was expected to produce. 



RAW MATERIALS 



Many of the specifications were written around the specific needs of 

 the job and embodied requirements that were considerably more strin- 

 gent than those imposed on similar materials for commercial use. As a 

 result, it was necessary for many suppliers to refine their processes, and, 

 in some cases, to produce the material on a laboratory basis. 



One example is the container, or repeater enclosure, which consists, 

 in part, of a seamless copper tube approximately If inches in diameter 

 having a ^-inch wall and approximately 8 feet long. This material was 

 purchased in standard lengths of 10 feet. The basic material was re- 

 quired to be phosphorous deoxidized copper of 99.80 per cent purity. 

 The tubing, as delivered, had to be smooth, bright, and free from dirt, 

 grease, oxides (or other inclusions including copper chips), scale, voids, 

 laps, and slivers. Dents, pits, scratches, and other mechanical defects 

 could not be greater than 0.003 inch in depth. The tubing had to be 

 concentric within 0.002 inch and the curvature in a 10-foot length not 

 exceed | inch to facilitate assembly over the steel rings. 



