From a two-ton coil of raw aluminum stock to the finished product, a ZERO Halliburton aluminum travel case goes through over 250 operations…mostly by hand. Case shells are produced from a special 2024 aluminum alloy. Large, specially designed presses, rated at 150 to 200 tons, draw the raw aluminum sheet over precision steel dies in a process developed to assure exact dimensional uniformity on every shell.
The metal is not merely bent into shape by this process; the molecular structure of the aluminum is actually re-arranged to form a shell without any wrinkling or distortion in the finish surface. The average size shell requires three deep drawing operations to attain the finished configuration.
The first draw produces a simple rectangular shape which has concave sides. As a result of the extreme stresses placed on the metal in the drawing process, a condition known as work hardening occurs. This, then, requires the aluminum being annealed (softened by heating the shells in electronically controlled ovens) prior to accomplishing the second draw.
After annealing, the second draw is performed. This straightens the sides of the shells and initially forms the stiffening beads in the shell face. The shells are then mounted on special racks and are heat treated for a period of time in special ovens at 920°F. The heated racks are then removed and quickly transferred to the quenching area and submerged in a bath of cold water. The heating and quenching process changes the molecular structure of the aluminum from a loose (soft) to a cold (hard) composition, thus creating the tempered aluminum shell which is basic to all ZERO Halliburton aluminum cases. Alloy selection is very important to assure proper retention of the tempering process when working with aluminum.The third and final draw in the shell-forming process completes the forming of the four styling beads and draws out any distortions resulting from the heat treating (tempering) process.
It is interesting to note that the four styling beads in each case shell not only add to the stylish appeal of the finished product, but also perform a structural function by adding significant strength to the already tempered aluminum.
All shells have been drawn to the maximum depth of the die, and are transferred to a trimming area. They are mounted on depth control mandrels, which rotate against a horizontally mounted, carbon steel circular saw which precisely trims and debars each shell to the desired depth. This is particularly important to assure proper fit of the shells and the extruded and formed closure assemblies.
After being chemically degreased to remove all oil contamination from the trimming operation, the shells are forwarded to the final buffing area.
Before buffing actually begins, the shells are once again cleaned.
The actual surface preparation then consists of several different buffing and polishing operations, ranging from initial rough wheel smoothing-to remove any die marks or in-process abrasions-to the final smooth-wheel polishing buff which evenly burnishes the overall exterior of the shell.The buffing operations are all performed manually by specially trained operators, and require a very high degree of skill to apply the proper pressure to the right surface at the right time… an under-buffed or over-buffed finish would result in immediate rejection and scrapping of the shell.
From this point on, until the cases are anodized, every step of handling is performed by white-gloved personnel. This is an absolute necessity in the anodic finishing process because any contamination of the buffed surface by body acids on bare hands will cause an etching of the finish which is not removable. Thus, a shell so contaminated would have to be scrapped, because of cosmetic blemishes on the finished product.