The warm-up process in high-pressure die casting (HPDC) systems is an unavoidable step in every casting plant’s production day.  At the beginning of a shift, or after other equipment shutdowns, the die temperature is reduced below its normal, quasi-steady operating temperature.  Castings produced after periods of inactivity will experience excessive cooling rates when the molten metal contacts the die surface, resulting in defective castings.  Warm-up scrap contributes to: reduction in machine uptime, decreased throughput, increased scrap material, and unnecessary cycles on the die.  Further, the additional cycles which occur during the warm-up period contribute to more severe thermal fatigue when compared to normal production cycles.  For these reasons, warm-up scrap increases the overall operating cost of the casting process.  In this paper, a prototype heating system was designed and implemented to preheat aluminum casting dies to reduce warm-up scrap.  An electric-powered, bi-directional infrared heater having tungsten filament lamps was implemented to heat an H13 steel die used in the production of intermediate plates in automatic transmissions.  The performance of the heating system was quantified experimentally by measuring die temperatures under different heating conditions.  Die temperatures were measured in various locations within the die using embedded thermocouples.  A numerical model was also developed to simulate radiation heat transfer into the die, and the model was validated against the experimental results.  The model was parameterized using known optical properties for semi-transparent opaque surfaces, with the exception of the die surface.  The optical properties of the die surface were measured in a separate series of experiments.  The heating time was measured for different heater power levels, heater standoff distances, and with/without a polished stainless steel reflector.  Heating time was found been reduced by the reduction in heating distance, and significantly reduced by using the flat reflector.  The numerical model was validated against experimental measurements and the validated model was then used to evaluate different configurations to obtain a more uniform heating distribution and to avoid overheating of protrusions from the die surface. The strategic arrangement of the lamps was found to improve the uniformity of heat distribution and reduction of overheated zones, at the expense of less energy transfer into the die.  Therefore, the lamp arrangement must be designed based on the required heat distribution and geometry of the die while maintaining an acceptable heating rate for the application.  In future work, the validated model will be used to evaluate different lamp configurations and shaped reflectors to increase the power density of the heating system.


Development and Evaluation of an Infrared Heating System for Die Preheating

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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