vacuum frame

noun

printing a machine from which the air is extracted in order to obtain close contact between the surfaces of two materials, e.g. the film and plate during platemaking

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012