A Million Pieces of Mail

Mail sorting system requires compact, high performance, linear motion system

Even though e-mail, online bill-pay, and shopping are on the rise, print mail has by no means disappeared, and package distribution numbers in a steady climb. Mailing facilities are continually seeking new ways to improve delivery times and hasten the entire mail sorting process by integrating automaton and robotics into their facilities. Enter Capstone, a design manufacturer that specializes in automating the repetitive manual tasks associated with print mail.

Capstone designed a large-scale mail sorting and packaging system named Autoviri. The complete Autoviri packing system was gargantuan, with 99% complete packing automation from beginning to end. Capstone required a system that was robust, could operate at high speeds, and could run 24/7 with virtually no maintenance upkeep. The linear motion system also had to fit into the already specified profile Ellison had specified.

The Problem

Based on the initial loading and motion profile requirements, Ellison chose the compact MTB042 actuator from PBC Linear for its ability to fit into the narrow envelope of the transfer area. The initial prototype testing showed that unplanned impact forces and higher-than-expected moment loads were being placed on the MTB042 actuators due to variations in the re-used mail trays. These forces were occasionally resulting in interference and jams, with eventual damage to the actuator’s carriage. Their analysis found that the stock MTB042 actuator did not have enough load capacity for the unexpected loading that was occurring, but a larger actuator would not fit.

The PBC Linear solution

After evaluating the application with an on-site investigation, PBC Linear engineers used Finite Element Analysis (FEA) to model the loading, and then design and supply Capstone with special MTB042 actuators that were able to handle the impact loads and higher moments. PBC Linear was able to make additional improvements to the overall system design, including:

• Installation of an external Mini-Rail linear guide support on the side of the actuator for more pitch moment capacity and robust stability against impact load.
• Design of a reinforced carriage,
• Ports for the custom MTB042 so that the actuator body could be supplied with pressurized air for creating positive body pressure and preventing the ingress of paper dust.
• Installation of internal bearing blocks with extra seals for further protection against dust.

Results / ROI

Capstone’s Autoviri system with PBC Linear’s optimized actuator was an immediate success. The packaging system Ellison provided was able to continually run 24/7 without unplanned shutdowns, cycling up to 1 billion pieces of mail per year automatically.