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TECHNOLOGY
TECHNOLOGIE
Fig. 3: Influence of various operating conditions on the heating rate – not
coated
red: warm start in a encased module – 3.39 °C/s between 40 °C and 470 °C
green: warm start – 2.39 °C/s between 40 °C and 470 °C
blue: cold start – 1.84 °C/s between 40 °C and 470 °C
black: cold start and an inappropriate position of the casting within the
IR-module – 0.78 °C/s between 40 °C and 470 °C
Fig 4: Influence of the state of the surface on the heating rate;
warm start in a partially encased module
red: not coated – 2.85 °C/s between 40 °C and 470 °C
green and blue: two different coatings – 3.84 °C/s
respectively 3.94 °C/s between 40°C and 470°C
• Weight of the zone under direct
exposure to radiation: 1.5 kg
• Surface of the zone under direct exposure
to radiation: 0.078 m 2 per side
• Wall thickness of the zone under direct
exposure to radiation: 3-5 mm.
Fig. 2 presents an inappropriate position of
the casting within the IR-module; this leads
to a massive loss of the heating rate (see Fig.
3) and as consequence to a corresponding
reduction of the productivity.
The influence of various operating conditions
on the heating rate is shown in Fig. 3.
After the heating process the castings were
submitted to both a forced air and water cooling
and to a subsequent overaging (see Figs
4-5).
Experimental results
Under the oversimplification: merely the
zone under direct exposure to radiation will
be taken into consideration. Instant power
consumption was 8.42 kW per side
The mechanical properties (average of four
tests) are presented in Table 1.
Conclusion and
future prospects
The obtained mechanical
properties are more
than encouraging.
The design of the
IR-module is very
important for the optimisation
of the heat
transfer process. Modern
IR equipment can
be adapted to the casting
geometry.
Acknowledgement
The authors would like to thank Audi, Heraeus,
LOI-Italimpianti and Trimet for their
support.
as cast air cooling water cooling
Rp0.2 [MPa] 154 120 223
Rm [MPa] 301 214 300
At [%] 7.6 12.6 7.2
Heating regimes correspond to the red curve in Fig. 4
Table 1: Mechanical properties
References
Fig 5: Overaging (convection kiln)
[1] C. Samoila, L. Druga, L.Stan, Cuptoare si Instalatii
de Incalzire, EDP, Bukarest, 1983.
Authors
Dr. Dan Dragulin is head of Research and Development
at Belte AG, Delbrück, Germany.
Markus Belte is CEO of Belte AG, Delbrück, Germany.
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70 ALUMINIUM · 9/2013