Just looking at what the meaning of Gesenk and Anzug are I found casting die for Gesenk and taper or draft for Anzug. I did not find any google hits for the word Gesenkanzug at all, but my guess is that it is the "die draft or taper"
die halves. Draft, The taper given to walls, cores and other parts of the die cavity to permit easy ejection of the casting. E. EDM, ...
http://www.dynacast.com/die-casting/common-terms.html