The United States Postal Service (USPS) delivers more than 200 billion pieces of mail a year to more than 134 million delivery addresses. During the height of the holiday season, the USPS processes more than 300 million pieces of mail in one day. So when increasing volume demanded a new bar code scanner that could keep up with the work load, Microscan's MS-880 was called upon to do the job.

By switching to Microscan's MS-880 scanner, the USPS increased productivity by eliminating the special handling of thousands of totes with previously "unreadable" bar codes.

Rising several stories above downtown New York City, the Morgan Station Mail Processing Center in Manhattan is one of the largest USPS distribution facilities in the country. Thousands of feet of conveyor line transport bar-coded mail totes for processing throughout the facility. At the heart of the new sortation system are industrial bar code scanners mounted near the weigh scale on each line to record the weight and then divert the totes to their proper destination, based on the bar-coded zip code on each tote.

The center appeared to be a classic warehouse distribution application for bar codes. But when the existing 10-year-old scan heads began to fail, the USPS was surprised to find that only a few bar code scanners on the market could meet their application requirements because the quality of their bar code labels was just too poor. Not only was the print quality light, but the small, 10-mil bar code was enclosed in a cloudy plastic sleeve.

Microscan's Drop-In Solution

"This application had some of the toughest parameters I've seen in a material handling application," commented Kirk Thomas of K & T Electrical Contractors, the systems integrator for the project. "We had speed. We had distance, and we had a small, poor quality bar code. When you add in their very low profile conveyor system, you have a challenging application for any scanner. The MS-880, however, performed right out of the box. We didn't even need custom programming."

Due to the height and the quantity of the totes traveling on the conveyor, the scanner needed to be mounted at an approximate 45 degree angle a minimum of 3 and a half ft from the label (as shown here). With a read range of 20-90 in. and auto focus capabilities, the MS-880 easily scanned the labels on the totes under the read range requirements. The programmable sweeping raster enabled the MS-880 to scan the entire side of the oncoming totes, as well as the entire width of the conveyor line itself. Since the bar code label could be applied in either ladder or picket fence orientation, two MS-880s were set up in a cross pattern and daisy chained together, using an auto-configure feature. The discontinued scan heads were disconnected and the new MS-880s were installed and operating in less than two hours.

Return On Investment

The installation at the Manhattan facility included 42 MS-880 scanners. The USPS saw an immediate return on its investment. Previously, the USPS was achieving a read rate as low as 89%, but with the new scanners, read performance accuracy jumped to 99%, even on the difficult labels. The amount of time spent special-handling "no-reads" was dramatically reduced, increased maintenance costs required to keep the failing scan heads operational were eliminated, and productivity increased, as well.

Every year during the holiday season, the Seattle USPS processing center receives so many oversized parcels that they must lease 150,000 sq ft of warehouse space with 30 dock doors for a few weeks to process them. In the past, they used a manual sortation system, but increasing volumes demanded a more efficient solution. They turned to automation specialists Olympic Controls, in Wilsonville, OR, to help them design automated scan-while-you-band workstations that were still 100% portable.

When the USPS opened its holiday annex in December, 2003, it was operating a fully-automated system complete with hundreds of feet of roller conveyor lines, 8 weigh scale stations, and two network hubs connected to the main facility via a wireless network. The entire system was set up in 3 weeks and broken down in just a few days.

With the new system, large packages are unloaded, placed on a conveyor, and routed to one of 8 weigh stations. The bar code on the package is scanned by a Microscan MS-880 bar code reader; the data is sent to a Siemens PLC, where it is buffered and held until a good stable weight is reached by the scale. Once the weight is logged and matched with the bar code data, the data is sent to a network hub connected to the wireless network Starship. Starship looks up the zip code to find the best possible transportation route for the package and then tells the scan-while-you-band computer what information to print on the label. An operator then places the label on the package. Once the bar code readers scan the bar code, the package is routed to the right location for pickup by the designated carrier.

Olympic Controls recommended the Siemens S7 series PLC because it had two RS 485 data ports, allowing the PLC to receive data from both the bar code scanner and the scale at the same time. Since nearly 25% of the packages arrive at the facility without a bar code, a keyboard was connected to the same data port as the scanner by way of a keyboard wedge, enabling the operator to key in the zip code of packages missing bar codes. The MS-880 bar code readers (shown above) were selected for the application for their programmable read range and ability to consistently read poor quality, low contrast bar codes.

The automated system immediately improved production efficiency and shipping accuracy, handling 3 times the normal volume while still reducing cycle time and the number of people required to perform operations. Seattle USPS met all of its carrier deadlines ahead of schedule and was able to dispatch early each night during the holiday season, something it had never been able to accomplish with the previous manual system.