Even with the rise of e-mail, online bill paying, and online shopping, print mail is not disappearing. Mail facilities always seek new ways to improve delivery times by hastening the mail sorting and packing processes with integrated robotics and automation. Capstone specializes in automating the repetitive manual tasks associated with print mail. Recently, they designed a large-scale Autoviri mail sorting and packing system, which included a PBC Linear actuator to perform a transfer task. With PBC Linear’s support, Capstone built an automated system that processed 1,000,000 pieces of mail per shift.
The assignment was to develop a linear motion system to transfer the mail trays into the Ellison Technologies package-sleever, a subsystem of Capstone’s Autoviri mail system. Package-sleevers encapsulate the mail trays for shipping.
Capstone required a 24/7, environmentally robust, high speed, low maintenance, and form-fit actuator. Based on the loading and motion profile requirements, Ellison engineers chose the MT series linear actuators for the transfer function. Specifically, the compact MTB042 as it fit into the narrow transfer area.
FEA modification of the MTBO42 actuator resulted in a design with more load capacity without changing its physical size.
Due to variations in the re-used mail trays and sleevers, which would sometimes cause interferences and jams, prototype testing showed that the impact forces and moment loads on the MTB042 actuators were greater than expected, resulting in damage to the carriage. The stock MTB042 actuators did not have enough capacity for the actual load while a larger stock actuator that might have the capacity would not fit.
Ellison engaged PBC Linear engineers to discuss options, hoping to avoid major design refactoring and the inevitable resulting schedule slip. After assessing the technical situation on the ground, PBC engineers used Finite Element Analysis (FEA) to model the load. The results from which led to the design and production of a special MTB042 actuator to handle the higher impact loads and moments as seen in earlier prototype testing as well as fit the former profile.
For the MTB042, a reinforced carriage was designed, the actuator body was fitted with ports for pressurized air to prevent ingress of paper dust, and internal bearing blocks with seals were installed to further protect against dust. The design retained form-fit of the prior actuator while increasing the performance requirements, thus allowing a drop in replacement of the former actuator.
The packaging system was able to continually run 24/7 without unplanned maintenance, cycling up to 1 billion pieces of mail per year.
Filed Under: Actuators, Packaging, Linear motion • slides, Motion control • motor controls