Originally Published PMPN October
2004
Case History
Keeping Control Systems in the FamilyA packaging company’s sister division designs control systems for liquid fillers.
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| Bosch Rexroth’s control systems provide smooth operation for Bosch Packaging’s liquid fillers. |
Jeff Jackson, product manager for Bosch Packaging (Minneapolis), didn’t
have to look very far for a new control system for the company’s liquid-filler
machines. In fact, all he had to do was consult his own company directory.
That’s where he found Bosch Rexroth (Hoffman Estates, IL), a components
supplier to Bosch Packaging and other pharmaceutical and medical packaging machines.
The sister division to Bosch Packaging recently provided a precise control system
for its FLM 2000-, 4000-, and 6000-series liquid-filler machines. The machines
can perform two-fill operations at rates of 300 vials/min. and single-fill operations
up to 600 vials/min.
“It was really an optimal solution,” says Jackson. “They had
the technology, the parts, and the support. And the fact that they are part
of our company made it the easiest choice possible.”
Jackson explains that the system for loading liquid-filled pharmaceutical vials
into trays was formerly a mechanically driven four-axis ma-chine. Bosch Rexroth
redesigned it and incorporated servos and an integrated motion system. The result
was reduced costs and maintenance and improved reliability, according to Jackson.
Precise Control System
Bosch Rexroth’s challenge was to provide an extremely precise control system
to electronically synchronize 9–28 axes of motion. The system also had
to delicately handle the transport, filling, and check weigh processes of the
vials at high rates.
“It now runs at speeds of 400 per minute, 25% faster than the nonservo
design,” he says. The reconfigured machine uses four MKD digital servomotors
from Bosch Rexroth for all four axes of motion. An infeed of a row of trays
is one axis, the vertical and horizontal motions of the vial pick-and-place
device make up the second and third axes, and the indexing of the vial tray
comprises the fourth.
The machine’s servo controls are used to precisely synchronize the infeed
star wheel, transport system, nozzle motion, In Process Control (IPC) check
weigh system, pumps, stopper, outfeed starwheels, outfeed scroll, and outfeed
magazine. Empty vials are entered on one end of the machine, filled, checked,
stoppered, and dispensed to a handling system at the other end of the machine.
“It was a big step to get this all in place,” says Jackson. “But
the system was designed so well that it really made the entire process very
smooth.”
The servomotor that handles the vertical axis of the pick-and-place robot uses
two Bosch Rexroth ball screws to give it the required gear ratio. However, the
other three use Bosch Rexroth planetary gear boxes. “If you require slow
motion, the motor can still run at a speed it’s comfortable with while
the gearbox delivers the gear ratio required for the slower speed,” says
Jackson.
The Bosch Rexroth machine fills groups of vials in a continuous fashion. The
transport carrier is the machine’s master, to which all other servos are
synchronized. The machine contains an IPC weigh scale that can precisely weigh
the vials and adjust the fill level automatically on a continuous basis. The
filler and IPC systems use the robotic capabilities of the control system, which
has kinematic capabilities to provide exact motion profiles. “The kinematic
technology is complex,” says Jackson. “But it provides the best method
for this system.”
Intelligent Servo Drives
Jackson admits the project’s challenge was daunting at first. “It’s
an incredibly complicated process,” he says. Bosch Rexroth, however, offered
what he calls a “perfect” solution: multi-axis electronic line shafting
(ELS) and camming capabilities. The powerful multi-axis controller, capable
of up to 40 axes of servos, allows for demanding applications to be accomplished
on a single controller. The Bosch Rexroth PPC controller handles complete machine
control, including logic, motion, and I/O. The controller receives help from
four Bosch Rexroth Ecodrive intelligent servo drives, one for each servomotor.
“You don’t have to give the PPC controller the task of telling the
servomotors all the things they have to do,” says Jackson. “They get
the information they need from their drives. It really frees up processing time
because there aren’t as many algorithms and calculations to perform.”
In addition, Bosch Rexroth’s use of both ELS and robotics capabilities
allowed for a single control to run the entire machine. Control-based PLS and
multimaster functionality were also required to synchronize and track products
through the machine. Jackson explains that the control operates the infeeds,
transport, stoppering, and outfeed in a mode of operation involving ELS phase
synchronization. The nozzle motion, IPC, and pumps operate in ELS control cams
that are built on the fly based on recipe changes made through a Human Machine
Interface (HMI).
Since the distributed intelligent drives handle all time-critical functions
inside, those functions also occur much faster than if they were handled in
the controller, according to Jackson.
Cost Savings
One of the main benefits of the collaboration with Bosch Rexroth was the money
saved, according to Jackson. He says the integrated PPC controller means the
machine is less costly to build since there is no need for separate controllers.
The use of a pendant-style HMI screen, supplied by Xycom Automation (Saline,
MI), also saves costs. “The old model had an HMI screen, but it was placed
wherever the customer wanted it,” says Jackson. “That meant custom
engineering, extra time, and extra cost. With this pendant approach, we can
build the same standard machine for everybody.”
The Xycom Pro-Face HMI screen is linked with the Bosch Rexroth PPC controller
through serial data communication, says Jackson. In addition, a SERCOS communications
protocol is used as a motion control network. SERCOS digital communications
allow for on-the-fly programming changes based on dynamic changes on the machine.
Another benefit of the Bosch Rexroth system is the use of electronic line shafting.
“Along with the PPC, the shafting allows for absolute motor feedback and
the ability to run all axes off a single controller,” says Jackson. “It
allows for machine recovery after a jam or power outage. This way, everything
stays synchronized.”
Simplified Control Architecture
Bosch Rexroth also offered Bosch Packaging simplified control architecture.
“It communicates openly with all major interfaces,” says Jackson.
“The FLM utilizes the Ethernet TCP/IP and ControlNet interfaces on the
machine, and the control monitors each of the vials through the machine. If
there is a vial missing or a vial that was determined by the IPC check weigh
to not be filled properly, that vial is not stoppered and will be discarded
by the reject wheel.” All of those functions are done with the use of a
programmable limit-switch output from the control.
Both drive-based and control-based PLS functions control pneumatic gates and
vacuum functions for the infeed gates, stoppering, and product reject removal
from the outfeed starwheel, Jackson notes. Any changes in the machine recipe
or timing of the machine in different areas are sent as a variable change to
the controller. The PPC controller then makes changes to each of the axes. “This
allows for synchronizing and unsynchronizing of various sections of the machine
during normal operation,” says Jackson.
Successful Collaboration
Jackson reports that Bosch Packaging is working with Bosch Rexroth on further
projects. “There’s another one going on right now,” he says.
It’s also likely the two divisions will work together in the future. “Their
system works very openly,” says Jackson. “It was perfect for us and
easy to implement and use.”
Bosch Packaging is also working with two major pharmaceutical companies, according
to Jackson. Those projects involve companies changing over from a batch processing
system to the Bosch Rexroth continuous-line system.
Jackson says that Bosch Rexroth also fit the bill of a supplier who offered
a powerful solution that was well supported in North America, Europe, and Asia.
“The support we got from them was excellent. Bosch Packaging really needed
a strong worldwide support network for this project, and Bosch Rexroth provides
that,” he adds. “Using a Bosch Rexroth solution was just a smart choice,
especially since they’re a sister company.”
Copyright ©2004 Pharmaceutical & Medical Packaging News
