NSKK
In 1928 he became full professor of general and theoretical electrical engineering at the "Technische Hochschule" in Danzig, and later held the same position in Berlin. Küpfmüller joined the National Socialist Motor Corps in 1933. In the following year he also joined the SA. In 1937 Küpfmüller joined the NSDAP and became a member of the SS, where he reached the rank of Obersturmbannführer.