Pengaruh fluida dielektrik minyak jarak (Jatropha curcas) terhadap recast layer material SKD 61 dalam proses electric discharge machine (EDM) = The influence of dielectric fluid castor oil (Jatropha curcas)of the recast layer SKD 61 material in the process of electric discharge machine(EDM) (Fakultas Teknik Universitas Indonesia, 2013)