Infrared heat transfer for thin‐walled aluminium automotive castings – a novelty in the field of aluminium high pressure die casting demonstrating the high versatility of aluminium as all around 

materialMarkus Belte & Dan Dragulin

BELTE AG

Delbrück

Belte AG Hauptsitz, Werk f. Wärmebehandlung

Altheim

Belte AG, Werk f. Wärmebehandlung

The use of infrared radiation in the field of aluminum processing enables easier automation and control of the heat transfer processes and contributes to productivity enhancement. The electrical hardware of the infrared module allows for drastic improvements in the efficiency factor of the industrial equipment used for aluminum processing, while also reducing the pollution degree.

Dr. Dimitrie Popescu, Associate Professor, Old Dominion University, Norfolk, Virginia, USA

Preamble

Basics of heat transfer

content

experimental results

Heating

Tkiln = ct

Source: [3]

Basics of heat transfer

Heating

Vheating = ct

Source: [3]

Basics of heat transfer

source: [3]

Heating

Tsurface = ct

Basics of heat transfer

Temperature equalisation

Tkiln = ct

Basics of heat transfer

source: [3]

Basics of heat transfer

Temperature equalisation

Tsurface = ct

source: [3]

Basics of heat transfer

Temperature equalisation

q = 0

source: [3]

source: Heraeus Noblelight

Basics of heat transfer

source: Heraeus Noblelight

source: Schwing

Basics of heat transfer

source: 

Heraeus Noblelight

enables:

solution HT within the die or integrated in the HPDC‐cell

Basics of heat transfer

The application of infra‐red radiation to heat treatment of thin‐walled aluminium high pressure die castings is a process that is in the early stages of its development. The objective of the experiment presented in the paper was to analyze the heating rate of the casting and to study its corresponding mechanical properties. All experiments were realized using AUDI‐structural castings.Experimental conditions The casting process was performed by Trimet.IR Module 

Ground coverage: 108 kWCastingWeight: 2.5 kgWeight of the zone under direct exposure to radiation: 1.5 kgSurface of the zone under direct exposure to radiation: 0.078 m² /side Wall thickness of the zone under direct exposure to radiation: 3 – 5 mm 

experimental results

Fig. 1: Casting exposed to IR – between arrows the zone under direct exposure to radiation; distance casting – IR‐module: left: 10 cm ‐ right: 30 cm 

experimental results

The figure (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.

experimental results

Fig. 3: Influence of various operating conditions on the heating rate – not coatedred: warm start in a encased module –3.39°C/s between 40°C and 470°Cgreen: warm start –2.39°C/s between 40°C and 470°Cblue: cold start –1.84°C/s between 40°C and 470°Cblack: cold start and a inappropriate position of the casting within the IR‐module –0.78°C/s between 40°C and 470°C 

experimental results

Fig 4: Influence of the state of the surface on the heating rate[1]red: not coated – 2.85°C/s between 40°C and 470°Cgreen and blue: two different coatings – 3.84 respectively 3.94°C/s between 40°C and 470°C

[1] : warm start in a partially encased module

experimental results

Fig 5: Overaging (convection kiln)

experimental results

Tab. 1: mechanical properties[1]

7.212.67.6At [%]

300214301Rm [MPa]

223120154Rp0.2 [MPa]

water coolingair coolingas cast

[1] heating regimes correspond to the red curve in fig. 4

Conclusion & prospectsThe obtained mechanical properties are more than encouragingThe design of the IR-module is very important for the optimization of the heat transfer process. Modern IR equipment can be adapted to the casting geometry.

Acknowledgement to: AUDI, Heraeus, LOI‐Italimpianti and Trimet.

experimental results

[1] T. Dulamita – Teoria si Practica Tratamentelor Termice, Ed. Tehnica Bukarest, 1966

[2] experimental results: . D. Dragulin, M. Belte – Infrared heat transfer for thin‐walled aluminium castings Aluminium Journal, 9/2013 

[3] D. Frunzaverde – Tratamente Termice, Ed. Intergraf, Resita

Literatur

Vielen Dank!