Method of vacuum timing control

A method for inserting material into an envelope using an inserting machine, said envelope having a front panel, a back panel, and a flap connected to said front panel to overlap said back panel, the method including the steps of:

• transporting the envelope towards an inserting station of said machine on a transport means of said machine;
• deflecting at least portions of selected pieces of insertion material from stacks of insertion material respectively contained at a plurality of insertion supply stations proximate said transport means, said deflection being accomplished by applying to said selected pieces for a period of time a vacuum, said vacuum being applied through a suction means situated at each insertion supply station of said machine;
• extracting said selected pieces from each insertion supply station and depositing said selected pieces on said transport means;
• inserting said selected pieces into said envelope at said inserting station;
• and,
• selectively adjusting for each individual insertion supply station the period of time for the application of said vacuum through said suction means.