Optical electrophotoconductor drums and electrophotoconductive tubes
obtained via a direct chill metal casting apparatus for continuous or
semi-continuous casting of metal (DC casting). In particular, casting of
ingots of aluminum which provide the electrophotoconductive tubes that
are subsequently coated to produce drums for copier and printers is
presented. A gas-slip prepared surface of the tube results in a reduced
and limited size and number of defects of an aluminum alloy material
wherein the defects arise from a casting, subsequent extrusion, and
subsequent drawing process. The defects arise primarily from either
feather line lamination defects or from weld-line defects where the
lamination defects are characterized by at least a slightly rougher
surface and often a different chemical composition than that of the
aluminum alloy at one point in the feather line lamination and where the
weld-line defects occur in the extrusion process from contaminants
present in either an aluminum casted ingot or log. Preparation of the
special surface for the subsequently coated optical photoconductive drum
results in increased yield, higher quality and lower manufacturing costs.