2SummaryThis article shows the superiority of the Infra-Red 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.
3Three modes of Heat Transfer： ConductionConvectionRadiation
4Traditional 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.
5A 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.
6UNEVEN 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.All the dies in a convection chest oven are under the same lid,Heated air escapes every time the lid is opened.
7Convection Air Flow Oven InletOutletDirection of AirDie
83. 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.
10What 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.
11What 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.
12What 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.
13Properties of IR Material generates heat after absorption Reflection or Transmission
14Novatec Infra-Red Die Oven About NovatecNovatec 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.
15Past attempts to use Infra-Red waves involved broad band heating 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.
17Advantage 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 flexibility5. Improves extrusion surface finish6. Superior safety features7. Advanced PLC control
181. 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.
20Heat Time Comparison： Press (T) Die Size (Dia. X thickness) (mm) Die Temp(℃)Heat TimeInfra-RedConvection2800430 x 3304752Hrs 30mins4~5Hrs430 x 1902hrs 00mins3680520 x 2452Hrs 15mins5~6Hrs520 x 3404802Hrs 35mins
212. 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.
22Extrusion Die Oven - Electricity Usage Comparison Convection Air Flow OvenNOVATEC Infra-Red OvenEach Cavity：10 Dies kW V2 Dies kW VDie Heat Up Cycle：8Hours X kW/hr =163.2 kWh@ 85% Power DrawDie Heat Up Cycle ：1Hour X 18.7k W/hr = 18.7 kWhTotal Cycle：8 Hours163.2 kW X $0.07 kWh = $11.421 Hour18.7 kW X $0.07 kWh = $1.31Total Cost to Heat Each Die：$11.42 ÷ 10 = $1.14$1.31 ÷ 2 = $0.65Die Temperature Holding Cycle：20.4 kWh÷10 Dies X $0.07/kWh= $0.14 Per Die Per Hour0.5 kWh÷2 Dies X $0.07/kWh= $ Per Die Per HourThe Infra-Red Oven is 52% more cost effective than a Convection Oven.
233. 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.
254. 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.
265. 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.
276. Superior Safety Features Watchdog thermocouple system and backup Mechanical Contactor prevents thermal run awayStatic lid stops that will activate under any non-normal condition, i.e. power outage, power spikeEmergency Stop Push ButtonAnnealing Light
287. Advanced PLC ControlUnique PLC System Automation Control
29ORION 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.TemperatureReal Time and Historical TrendsProfile open, edit, save and download!
32Be 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.
33Contact Us Head Office Ph. 604-888-3328 Fax. 604-888-4538