Control System Improves Heat-Treating Precision
Fred Vodde, Honeywell Control Products, Fort Washington, Pa., Robert Lontoc,
Honeywell Sensing and Control, Freeport, Ill., and Glenn Van Zyl, Thermal
Control Systems Inc., Monee, Ill.
An upgraded process-control system featuring a multiloop control scheme
creates a showcase environment in IITRI's R&D facility to help expand the
customer base and meet the tight heat-treating control requirements of
projects for the U.S. Department of Defense and commercial clients.
IIT Research Institute's (IITRI)
Thermal Processing Center
(Chicago) is a unified technology
center capable of performing
manufacturing research and
development projects for
aerospace precision-gear and
similar industries. The research
and development facility wanted
to upgrade its process control to a
tighter control system that was
capable of data tracking and
security and that was more
Multiloop processor provides preformatted display screens,
reliable and accurate than the
graphic PID programming, alarms, diagnostics, set-point
one that was in place. Data
scheduling, and other features for precise process control.
collection and analysis is key to
subsequent commercial
implementation of the developed technology at IITRI's heat-treating facility.
The IITRI project involved upgrading process-control equipment on several furnaces, a gas
generator and a cryogenic treatment unit-control equipment that was state-of-the art just a few
years ago according to IITRI heat treating facility manager Joseph Shenosky. IITRI's objectives
included:
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Improving temperature and process control
Installing and using the best available technology for present and future R&D projects
Providing process recipe and set-point scheduler functions
Developing a control algorithm using real-time gas analysis data
Having the capability to meet future customers' thermal processing requirements
IITRI's goal upon completion of the project was to have a showcase environment to help perform
and sell R&D projects to prospective customers in both the government and commercial arenas.
Control requirements
To meet IITRI's stringent
requirements, the control system
had to have the following
capabilities:
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The hardware and
software system had to
be compatible with the
facility's existing plant
floor equipment
The improved control
schemes had to reuse
existing sensors and
actuators
The control equipment
had to provide unlimited
data storage and access
to variables both during
and after project
completion
Data had to be
accessible in
spreadsheet and trend
format with back-up on a
mirror hard drive, on CDRW and as hard copy for
client and internal use
Process data and
variables had to be
accessible from offices in
(1)Function block concept used in UMC 800 controller PID
Chicago and remotely
loop graphic (2) Furnace temperature, process gases and
over the Internet via
other parameters are controlled via multiloop controller.
modem
The system had to have
data security functions to restrict access to sensitive information
The software had to be operator-friendly for configuration and customization
The equipment had to have the ability to integrate other measurement and testing
equipment into a common database and control scheme
The control-upgrade plan selected by IITRI was that of Thermal Control Systems Inc., (Thercon)
of Monee, Ill., a furnace designer and systems integrator in the heat-treating industry. The initial
plan specified the incorporation of Honeywell UMC800 multiloop process controllers, Honeywell
UDC3300 single-loop controllers, Honeywell VRX180 paperless data recorders, a multigas
analyzer and a computer station. IITRI later changed its requirement for the gas analyzer,
preferring to incorporate a laser gas analyzer developed by Atmosphere Recovery Inc., (ARI) of
Plymouth, Minn., for use in monitoring heat treating process and control applications. ARI's
analyzer is capable of simultaneously analyzing eight different gases relevant to the carburizing/
carbonitriting heat treating process. Thercon developed a scheme to integrate the laser gas
analyzer into UMC800 multiloop controller. The modular control approach permits upgrading PC
software and individual control instruments at a later date without affecting the integrity of the
overall system.
Equipment selection
The primary goal of the project was to
provide a control system having local PID
control at each furnace and networking
capabilities that permitted interface and
data acquisition from the PC station. The
UMC800 multiloop controller having setpoint recipe capabilities was selected for
its ability to perform process control on
multiple furnaces with up to 16 PID loops
of control. All IITRI's furnaces and its gas
generator use multiple control loops for
temperature and process gas control. The
UMC800 also is capable of providing loop
control of the process control gas valves.
The UMC's Control Builder graphic
programming software, alarms,
diagnostics, set-point scheduling, data
acquisition and many other features made
it the preferred choice for use in the
process-control application. The UMC
Local Operator Interface allows for local
control through preformatted display
screens, which makes it easy for the
operators to use. The Operator Interface
also has a disk drive that allows for
redundant backup of process data and
provides the ability to quickly
upload/download the configuration
program. In addition, the laser gas
analyzer could be integrated into the
UMC800's carbon control algorithm.
For temperature control on the temper
furnaces and cryogenic treatment unit, the
Honeywell UDC controllers were selected
together with new logic control for all
control functions. These controllers
provide up to two loops of control, alarms,
local operator interface and set-point
(1) Laser gas analyzer samples eight gases
programming. All of IITRI's existing
sequentially, with updates as rapid as 15 seconds.
furnace sensors and actuators were
(2 & 3) ARI laser gas analyzer and UDC 3300 and
reused.
UMC 800 controllers in Lindberg GVRT control
panel. The laser gas analyzer is integrated into the
IITRI's customers require certification of
UMC 800 carbon-control algorithm.
all heat-treating equipment. The VRX180
paperless recorder including an LCD video display was selected to record process data. The
recorder is used on a moveable cart with plug-in jacks to an Ethernet connection at any of the
control equipment. The recorder provides operator interface and network interface for up to 24
thermocouples during temperature uniformity surveys of the heat-treating equipment. The
paperless recorder provides the benefit of eliminating the need change paper and pens
regularly, as all the data is saved on an integral disk drive. The information on the disk is saved
in an encrypted format to ensure secure and tamper-proof information.
The IITRI project presented several programming challenges. The facility's equipment came
from various vendors having different addressing and communications protocols. It was
imperative that all of the heat-treating equipment could operate independently, so if any
individual piece of equipment failed, the rest of the controllers would continue to operate without
interruption. The human-machine interface (HMI) software had to have the capability of
communicating (read/ write) with the OPC server, instruments and valves. Because IITRI is a
research and development facility, the software and instrumentation also had to have the
capability to be reconfigured to perform customized testing. The process-control scheme that
was installed addressed these challenges while allowing for simplified future expansion of the
control scheme.
System performance
The control system upgrade has resulted
in increased control accuracy and
temperature uniformity. IITRI's integral
quench furnace is now capable of
uniformity in the range of I3?F (I1.5C) at
operating temperatures between 1400 and
1700F (760 and 930C). IITRI's facility
manager noted that a uniformity of I10F
(I5.5C) is considered to be precision heat
treating, so the I3F uniformity being
achieved using the new control system
offers "better-than-precision" heat treating.
IITRI can now test traditional and
Heat-treating R&D projects for the aerospace
nontraditional process gas mixtures.
precision-gear industry are among the capabilities
Simple reconfiguration of the UMC 800's
of the IITRI Thermal Processing Center.
control algorithm permits running tests to
exactly match a customer's requirements.
The laser gas analyzer provides precise and rapid analysis of eight process gases to accuracy
levels of less than 0.25% of full scale. Infrared and other methods of process gas analysis do
not match the real-time gas analysis capabilities of the laser gas analysis (LGA). LGA also
permits implementation of advanced real-time control schemes.
The accompanying Citect data acquisition software and programming configuration permits
collecting virtually unlimited data on all variables relating to the heat treating of particular loads.
The data can be recorded and compiled in any format that meets IITRI's or its customers'
requirements. All current and historical process data can be accessed and analyzed from either
the PC station in Chicago or remotely via the Internet.
The upgrade also allows IITRI to develop production procedures to minimize process cycle
times and maximize metallurgical properties.
The UDC3300 controllers were field-upgraded to incorporate Honeywell's Health-Watch
diagnostic software. The software increases productivity and reduces downtime and
maintenance costs by triggering an alarm in the controller when it detects a problem with the
process, thereby avoiding a shutdown.
For more information: Contact Fred Vodde, Honeywell Control Products, 1100 Virginia Dr., Fort
Washington, PA 19034; tel: 215-641-3798; fax: 215-641-3599; e-mail:
[email protected]