Processing Flats

Building on the success of its letter automation program, the Postal Service began to automate the processing of flats. Largely comprised of catalogs, magazines, and oversize envelopes, flats make up nearly 30 percent of the mailstream.

In 1982, the Postal Service deployed its first flat sorting machine (FSM), the FSM 775. Previously, all flats had been processed manually. With four operators keying in part of the ZIP Code, the FSM 775 could sort about 6,200 flats per hour into 100 bins. The FSM 881, introduced ten years later in 1992, could sort about 10,000 flats per hour with four operators.

In 1996, FSM 1000s were introduced to handle the one out of four flats that could not go through the FSM 881s, including newspapers, poly-wrapped material, and flats weighing more than 20 ounces. In 1998, the Postal Service began upgrading flat sorting machines, adding barcode readers to FSM 1000s and optical character readers to FSM 881s. Beginning in 2002, automated flats feeders and optical character readers were added to the FMS 1000s, improving the machines’ throughputs and reducing the number of people required to staff them.

The first fully automated flat sorting machine (AFSM 100) was installed in Baltimore, Maryland, in 1999. Each AFSM can process 300,000 flats a day, almost three times as many as the equipment it replaced. The AFSM 100 has a video encoding feature that sends images of unreadable addresses to the remote barcoding sytem for barcoding, without removing the mail from mailstream. Widescale deployment of AFSM 100s was completed in 2002 with 534 systems installed at 240 mail processing facilities nationwide.

In 2004, the Postal Service began to install a system called flat ID code sort on all AFSM 100s. It tags each flat with a special identification code. Subsequent operations to sort the flats use these ID tags. Beginning in 2005, automatic induction systems and automatic tray handling systems were added to AFSM 100s, saving even more manual labor. Automatic induction systems feed flats into the machine, and tray handling systems automatically label and offload full trays of sorted mail and reload the machine with empty trays.

By 2005, flats productivity had nearly doubled in processing facilities, with about 80 percent of flats processed on the AFSM 100, but time spent sorting flats at delivery offices remained the same. Letter carriers spent an average of three hours a day sorting their mail into delivery order. Unlike most letters, flats did not arrive in delivery order. In the late 1990s, the Postal Service began to explore ways to sort flats into delivery order or “carrier walk” sequence. In April 2006, a prototype flats sequencing system was installed in Indianapolis for field testing.