Fraunhofer Institute for Ceramic Technologies and Systems IKTS
Thermal Furnace Simulation: Improved Energy Efficiency in Hardmetals Sintering
Current research
Fig. 1: Thermal conductivity of the cemented carbide used as a function of temperature.
Fig. 2: Temperature distribution in the sintering furnance, including the sintering batch at the start of the holding time.
As cutting materials for machining tools, hardmetals are essential to modern manufacturing processes. The aim of the joint BMWE research project “AM Werkzeuge” (funding code: 03EN4010) was to reduce the energy demand involved in the production of cemented carbide tools across the entire process chain. One of the most energy-intensive process steps is the sintering of the green body into a solid, dense component. Understanding the processes taking place in the sintering furnace is key to gaining insight into the process and provides the basis for optimization. Thermal modeling and simulation make a valuable contribution in this context.
Model parameters here include the temperature-dependent thermophysical properties of both the material to be sintered and of the furnace materials. Using thermodilatometry/thermomechanical analysis (DIL/TMA), differential scanning calorimetry (DSC), and laser flash analysis (LFA), it was possible to determine the coefficients of thermal expansion, heat capacity, thermal diffusivity, and thermal conductivity up to temperatures of 1500 °C (Fig. 1).
In addition, the project involved the development of a three-dimensional, transient thermal model of a vacuum sintering furnace belonging to an industrial partner. The objective of the model-based thermal analysis was to identify potential energy savings and quantify thermal gradients across the sintering charge. The model enables temporally and spatially resolved calculation of the temperature field of both the sintering charge and the sintering furnace (Fig. 2).
The model was used to predict energy demand during the heating phase of the sintering process and analyze the influence of various process conditions. Aspects under investigation included the impact of lower maximum sintering temperatures and shorter holding times on energy consumption. Overall, an energy saving of 8 % was achieved during sintering. The model was validated using temperature measurement rings and measurements of electrical heating power. It can also be used for model-predictive control of the sintering furnace.
Services offered
- Thermal simulation of industrial furnaces
- Determination of thermophysical material properties
- Design of energy-optimized sintering conditions
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