[3] In 1923 Gruner ended his secondary education in Leipzig with the abitur and was enrolled at the Technical University of Dresden in the same year.
In 1943 Gruner was appointed as lecturer in the field of non-cutting shaping of sheet metal at the Braunschweig University of Technology, an appointment to the RWTH Aachen University in late 1944 was hindered by the advance of the Western Allies.
Gruner received emeritus status in 1969, but held lectures at the Dresden University of Technology until 1978.
[5] He died in Dresden and his grave is located in the cemetery Waldfriedhof Weißer Hirsch in the eastern borough of Loschwitz above the right bank of the Elbe.
In 1979 he was appointed Honorary Senator of the TU Dresden and in the same year received the Dr. h.c. from the Wilhelm Pieck University in Rostock.