By Jim Montague, Executive Editor
Just as it can be hard to see the forest for the trees, sometimes it's hard to see an overall production system for all its machines and components. In the woods, the trick is to get up above the trees and look down. In manufacturing, a thorough and dynamic simulation can give machine builders the overall operating perspective they need before construction.
Even Experts Need Tools
MTS Medication Technologies (www.mts-mt.com) has been building drug packaging systems for more than 25 years, and its engineers are experts at designing and building increasingly automated and patient-specific prescription packaging machines and related equipment. As a result, it typically has long-term relationships with many pharmacy customers.
However, about three years ago, a large European pharmacy company began seeking a way to centralize supplying medicine to its hundreds of retail pharmacies across regions and even countries, so MTS proposed designing a much larger retrieval and packaging system with more feeder stations, robots and other supporting devices than it had ever built before. To best coordinate all these components, MTS and its engineers knew they would have to design and test numerous new operating variables and parameters, and so they decided to use simulation to speed up this process, save time and expenses, and build fewer prototypes.
"Each pharmacy traditionally fills its own prescriptions, mostly by hand, and so our customer was looking to consolidate a lot of its usual distribution efforts into just one or a few centrally located systems," says Robert Barrett, MTS's controls, software and mechanical engineering fellow.
From Punch Cards to Robots
Located in St. Petersburg, Fla., MTS manufactures medication packaging systems, related consumable packaging, software and pharmacy information system interfaces. The company serves more than 9,000 institutional pharmacies in the long-term care and correctional-facility markets in the U.S. and also internationally.
Founded in 1984 by practicing pharmacist Harold Siegel, MTS developed the first automated packaging machine to fill and seal medications into disposable punch cards, and now has a product line that includes automated and semi-automated packaging machines and hundreds of consumable products.
"MTS started out making punch cards, labels and blister packs, and it eventually just made sense for us to move into building machines that would allow our customers to use these end products more efficiently," Barrett says.
"With the level of complexity and multitude of variables involved with this type of system, a static design simply would not cut it."
The company's standard line of packaging machines are designed to fill, seal and label punch cards at up to 12 cards per minute. Many typically have one feeder station, conveyor system and robot. Equipped with automated barcode verification and tracking, the machines allow pharmacies to fill prescriptions as soon as they receive the orders. Their automation also helps ensure packaging accuracy, and lets users grow their businesses without adding staff.
Barrett adds that MTS's OnDemand machines employ a variety of robots and motion control software, and then use single-board computers and backplanes to interact with and control I/O devices. "These embedded computers allow us to use an embedded Ethernet adapter to distribute I/O and process data throughout our whole machine, and control different parts of it," he explains. "We also do PC-based control via Visual Basic by using multi-threading and ActiveX objects to instruct other motion devices such as servo motors and servo actuators. We also overlay an Oracle database on top, which allows different areas of our systems to understand what they need to do and when to do it."
Centralization Demands Coordination
To enable the European pharmacy firm to fill prescriptions from so many retail outlets in one or a few locations, MTS estimated the larger CentraFill packaging system would need about 30 feeder stations to dispense multiple medications into multiple compartments on one punch card with daily doses arranged by week or month. For example, if a patient needed medication four times per day, the machine would produce a 4x7 punch card for a one-week supply.
"Our larger machine also needed three different types of filling areas," Barrett adds. "The first is dedicated to high-speed filling of single medications. The second uses two robots to pick drugs from 104 different cassettes, and place them in the packages. The third is a more manual station for handling partial tablets."
In addition, besides employing up to a dozen or more robots working together simultaneously, the many feeder stations are located along a 120 m track occupied by dozens of small, independent, servo-driven, 400 mm pallets. Each pallet is dedicated to filling one prescription, so it visits assigned feeders, and cycles through the machine along the track until it's completed.
Though the larger machine's design combines many of MTS's existing components and expertise, it also presented many new complexities for which the builder had no prior design concept. As a result, MTS was faced with testing and validating many new variables to minimize risk, optimize engineering time and secure buy-in from its European end user. One of the biggest challenges was determining the precise number and configuration of the machine's many feeder stations to prevent over-engineering the machine or miscalculating the volume of support equipment it would require. MTS also needed to give its customer an accurate cost estimate for the machine, determine its footprint, and verify its production rate and throughput. Finally, the customer wanted the machine's design to be scalable to meet future demands.