Co-Line Welding, Inc.
Achieves ±1°F Uniformity in Solution Heat Treatment System with
Jet Impingement Technology
by Jack
Mahoney, Sales Applications Engineer
This case study details the heat treating
system that was manufactured and installed in the Co-Line
Welding, Inc. plant located in Sully, Iowa.
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Roller Hearth Solution
Heat Treatment System with Integral Quench and Age Oven |
Co-Line Welding, Inc. opened a small welding shop in 1979
with two employees for local farm and commercial repairs. Almost 30 years
later with over 120 employees, Co-Line has expanded to serve a multitude of customers in a variety of industries. Today,
Co-Line offers tool and die services, metal stamping, metal fabrication, CNC machining, production and robotic welding, painting, jig & fixture building, farm and commercial repair, portable welding and 3-D laser cutting. As of early 2006,
Co-Line added heat treating to their already long list of capabilities.
The work regularly processed in this
furnace is a two part aluminum stamping.
The stamping is a thin gauge 6001 alloy, and the parts
are welded prior to heat treating.
The final product is confidential which restricts us from
including sensitive details regarding the use.
However, we can say that the heat treating process must
consistently conform to AMS specification 2770.
After the arrangement and sizing tasks were
complete, SECO/WARWICK was contracted for the design,
manufacturing and start up of an electrically heated,
semi-continuous roller hearth solution heat treat furnace and
water quench, plus a separate batch age oven.
Jet Impingement Air Flow
Technology
Because of concerns regarding the critical
nature of the work, particularly in the area of heating rate and
temperature uniformity, our newly patented jet
impingement air flow design was supplied.
The time required to reach solutionizing temperature has
an obvious impact on the cycle time.
A fast heating rate means that the hold or soak period can
begin sooner, which will reduce the total cycle time.
Prior to the start of the soak period, the entire load must
reach a minimum temperature.
Because of the gauge thickness of the alloy Co-Line is
processing, the heating rate uniformity is addressed in the jet
impingement design to assure the entire load is exposed to the
same thermal conditions. Following
heat up, the hold or soak period required by the AMS
specifications, followed. The
temperature uniformity of the aluminum remained with the range
of ±1°F of the temperature setpoint throughout the duration of the soak
period. By far this
has been the most uniform temperatures ever achieved in a high
volume production application.
After solution heat treating, the work is placed into a
multi-load batch type age oven to complete the cycle and the
hardening process.
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Charge side of furnace |
Hands-off Sequence of Operation
Another advantage seen by Co-Line is the
essentially hands-off sequence of operation. Baskets are placed
at the charge side of the furnace by a fork truck, and not
handled again until they are removed from the exit end discharge
table. The furnace
will load, heat treat, quench and discharge continually without
operator assistance. Multiple
baskets can be positioned at the charge end.
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Batch style Age Oven |
The front door opens and each load is
driven into the furnace by motor driven alloy rolls.
After the heat and soak cycle is complete, the rear door
opens and the load is driven out of the furnace, onto the quench
elevator and quickly lowered into the water for cooling.
After cooling, the elevator raises the load back up for
draining, then discharges onto the exit end conveyor.
The operator removes the load and places it into the
multi-load batch style age oven where the age process completes
the cycle.
Control
Temperatures are maintained within the
furnace by strategically located thermocouples reading airstream
temperatures of the impingement air prior to entering the load
space. Reading the
air temperatures inches away from the work as it is directed
into the work chamber, permits the maximum allowable wind
temperatures to be used. Equal
distribution of the air, in both temperature and pressure
assures Co-Line that all portions of the load will be evenly
heated.
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Floor mounted quench
tank |
After heat treating, the fast transfer of
work out of the furnace and into the floor mounted quench tank completes
the furnace cycle. Work
temperatures and times are recorded for archiving the process
data.
As tested and surveyed at
Co-Line, the jet
impingement furnace design shows an unequalled combination of
air flow uniformity, heat transfer rates and load uniformity.
The system expands Co-Line's manufacturing capabilities
and supports their goal of serving customers with a one-stop
shop to meet their metal working needs.
For more information on Co-Line manufacturing, visit www.colinemfg.com.
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