The superiority of the Infra-Red technology over

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Novatec Infra-Red Die Oven
Summary
This article shows the superiority of the InfraRed technology over convection air flow. The
comparison is through theory, heating process
and efficiency.
Short cycle heating and die management is one
of the most significant technology reforms of
the extrusion industry in the past 20 years.
Three modes of Heat Transfer:
1.Conduction
2.Convection
3.Radiation
Traditional Air Flow Chest Oven:
•The chest oven, holding multiple extrusion dies, has been the
most common design over the years. The tooling is heated by
circulating hot air through a common chamber using a blower
system. This is the convection air process.
•An extrusion die that does not have accurate temperature
throughout or uneven temperature profile on the face will not run
properly. In this case more billet is used before accurate profiles
can be produced to correct the differences. Short production
runs produce off-tolerance material and high die failure.
• A single lid oven exposes the dies to a fresh supply of
oxygen and moisture each time the lid is opened. This is
another cause of rapid oxidation.
• Die management is virtually impossible so the solution
is to heat lots of dies in case of extrusion issues. This
means that dies are left at elevated temperatures for
extended periods of time. The die bearing is exposed to
rapid oxidation unnecessarily.
UNEVEN HEATING
Why convection air heats dies unevenly:
1. The air being blown in a die box will travel the path of least
resistance from inlet to outlet in the convection process. The
physical blockage of the air stream causes uneven exposure
to the die surface.
2. All the dies in a convection chest oven are under the same lid,
Heated air escapes every time the lid is opened.
Convection Air Flow Oven
Inlet
Outlet
Die
Direction of Air
3. Placing a cold die in the air stream will cool the temperature for
the dies further away causing incorrect heat time. It is virtually
impossible to avoid this in the die exchange process. Heated dies
are then actually cooled without operator knowledge. The biggest
cause of unevenly heated dies is when a cold die is placed next
to a hot die causing the heated die face to be cooled on one side.
This thermal gradient is the cause of die breakage, poor run out
and inaccurate non-conformant extrusion dimensions using the
first billet.
Heating Extrusion Dies
Using
Infra-Red Technology
What is “Infra-Red” Heating?
Most extruders use traditional convection chest ovens
for die heating. The air in a common chamber is heated and
circulated. The convection process relies on air temperature to
transfer energy to the steel through conduction. This procedure
is slow and inefficient.
Infra-Red energy uses a band of electromagnetic waves
to “excite” the metal molecules in a die through radiation. This
molecular excitation is similar to the microwave technology.
Infra-Red energy does not use air temperature for thermal
transfer. Air is an insulator so the thermal process is accelerated.
What is “Infra-Red” Heating?
Infra-Red is a kind of Radiation which transfer heat from object
to another by electromagnetic transmission. The Infra-Red is
located between visible light and radio in the electromagnetic
spectrum. The wavelength of Infra-Red ranges from 2.0 to 6.0
microns.
What is “Infra-Red Heating?
When the Infra-Red energy reaches the surface to be heated,
the molecules vibrate, converting to heat energy. Heat then
travels through the product by conduction.
Properties
of IR
Material generates
heat after absorption
Reflection or
Transmission
Novatec Infra-Red Die Oven
About Novatec
Novatec is based in Surrey, British Columbia .The company has
been producing Infra-Red equipment for a variety of applications for
the past 20 years. In 1990, an aluminum extruder asked Novatec to
explore the possibility of heating extrusion dies with Infra-Red
technology, and the Novatec Infra-Red Die Oven was developed.
Since that time, a number of extruders have installed the ovens and
have reported dramatic improvements in speed, flexibility, and
quality.
Past attempts to use Infra-Red waves involved broad
band heating. Generating this spectrum was not energy
efficient.
Novatec has developed the Infra-Red band technology
to focus the wave energy to match the absorption in steel.
Generating a small band of Infra-Red waves gives a focus
energy for absorption. This maximizes energy transfer.
Spectrum Absorption
100
% Absorption
80
60
Metal
40
20
0
1
2
3
4
5
6
Infra-Red Wave Length (Micron)
7
8
Advantage of using Novatec
Infra-Red Die Oven:
1. Cuts die heat up time by 75%
2. Reduces energy consumption by 50%
3. Reduces die failure by 90%
4. Increases speed and flexibility
5. Improves extrusion surface finish
6. Superior safety features
7. Advanced PLC control
1. Cuts die heat up time by 75%
Novatec Infra-Red Die Ovens heat dies much faster
than convection ovens. As explained above, this is because
the dies are being heated by infrared waves, not air. Air
itself is an insulator of thermal energy, and therefore, is a
poor medium for thermal transfer. Novatec’s Infra-Red Die
Ovens single out the wavelength needed to heat die steel
only…not heat all the air in the oven.
Heater Efficiency Comparison
Emission Ratio
0.95
1
0.9
0.8
0.7
0.6
0.55
0.5
0.4
0.3
0.2
0.1
0
Metal Sheath
Heater
Novatec Black Body
Infra-Red Heater
Heat Time Comparison:
Press
(T)
Die Size
(Dia. X thickness)
(mm)
Die
Temp
(℃)
Heat Time
2800
430 x 330
475
2Hrs 30mins
4~5Hrs
2800
430 x 190
475
2hrs 00mins
4~5Hrs
3680
520 x 245
475
2Hrs 15mins
5~6Hrs
3680
520 x 340
480
2Hrs 35mins
5~6Hrs
Infra-Red
Convection
2. Reduce energy consumption by 50%
Because of the wavelength heating process explained
above, the efficiency of the die heating process is greatly
improved. Not only does the level of heating time reduce overall,
but also the power draw to maintain oven temperature once
heated is less than 500 watts. (By contrast, a typical hair dryer
operates on 1200 to 1400 watts.) The savings on power usage
alone is a significant benefit when using Novatec’s Infra-Red Die
Oven.
Extrusion Die Oven - Electricity Usage Comparison
Convection Air Flow Oven
NOVATEC Infra-Red Oven
Each Cavity:
10 Dies 24 kW
Each Cavity:
2 Dies 22 kW
480V
480V
Die Heat Up Cycle:
8Hours X 20.4 kW/hr =163.2 kWh
@ 85% Power Draw
Die Heat Up Cycle :
1Hour X 18.7k W/hr = 18.7 kWh
@ 85% Power Draw
Total Cycle:
8 Hours
163.2 kW X $0.07 kWh = $11.42
Total Cycle:
1 Hour
18.7 kW X $0.07 kWh = $1.31
Total Cost to Heat Each Die:
$11.42 ÷ 10 = $1.14
Total Cost to Heat Each Die:
$1.31 ÷ 2 = $0.65
Die Temperature Holding Cycle:
20.4 kWh÷10 Dies X $0.07/kWh
= $0.14 Per Die Per Hour
Die Temperature Holding Cycle:
0.5 kWh÷2 Dies X $0.07/kWh
= $0.0175 Per Die Per Hour
The Infra-Red Oven is 52% more cost effective than a Convection Oven.
3. Reduces Die Failure up to 90%
Extruders who use the Novatec Infra-Red Die Ovens have
reported a dramatic decrease in die failure and breakage. Not only
do convection ovens take longer to heat a die, they heat dies
unevenly. Studies show that even after four hours of soak time in a
convection oven, a 14 inch die can have as much as a 100 degree
difference between one side of the die to the other. This will cause
uneven runout in multi-hole dies, and consequently, uneven
stresses on the die. All of this results in premature die failure and
breakage and higher scrap rates. Novatec’s Infra-Red technology
heats dies to within single digit temperature variation throughout
the die, reducing die failure.
Temp (deg. F)
This Chart shows the heat up time for a 16"x 6" die at 4 different thermocouple
points in the die. Note the evenness of the heating throughout the die. It reached
target temperature in 91 minutes.
950
900
850
800
750
700
650
600
550
500
450
400
350
300
250
200
150
100
50
0
Oven Set Point
Front : 1" Deep
Middle : 3" Dep
Surface
Temperature
1
6
Back : 1" deep
11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 106 111 116 121 126 131 136
Time (min.)
4. Increases Speed and Flexibility
As mentioned above, a 14-inch die would be heated in
less than 60 minutes with a Novatec Infra-Red Die Oven, as
opposed to 4 hours in a convection oven. This will provide
increased flexibility of die changeovers on the extrusion press,
and reduce throughput time.
5. Improves surface finish of extrusions
Because the dies do not have to stay in the oven for 4+
hours, the die bearings are not subject to excessive oxidation
prior to extrusion. This provides a higher extrusion finish. Also,
airflow systems, such as those used in a convection oven, tend
to deposit particles on dies and bearings. Novatec Infra-Red
Die Ovens do not require an airflow system, and therefore,
keep the dies free of contaminants.
6. Superior Safety Features
• Watchdog thermocouple system and backup
Mechanical Contactor prevents thermal run away
• Static lid stops that will activate under any nonnormal condition, i.e. power outage, power spike
• Emergency Stop Push Button
• Annealing Light
7. Advanced PLC Control
Unique PLC System
Automation Control
ORION Series
Little, Tiny, SCADA !
Interface up to 20 loops of control. Include
profiling, single set-point recipes, trending,
alarm monitoring\history and graphic
objects for each loop, then add data
acquisition with historical viewing, and you
have ORION.
Temperature
Real Time and Historical Trends
Profile open, edit, save and download!
3 Cavity Oven
2 Cavity Oven
Drawer Oven
6 Cavity Oven
Be on the leading edge of extrusion technology!
We’re all looking for ways to stay ahead of the competition,
and this is especially true in the extrusion business. Novatec’s
Infra-Red technology is truly on the cutting edge for this industry.
It can be the key that gives your plant the edge you need over
your competitors. Don’t wait until they have one, too! Call
today and explore the possibilities of Novatec’s Infra-Red Die
Oven for your plant.
Contact Us
Head Office
Ph. 604-888-3328
Fax. 604-888-4538
Email: [email protected]
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