High Pressure Die Casting of Light Metals

1
High Pressure Die Castingof Light Metals

• Heat loss and heat transfer
• Ph.D. Raimo Helenius
• Supervisors Otto Lohne
• Lars Arnberg

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What is High Pressure Die Casting?
________

• Cold Chamber and Hot Chamber

• Casting method typically for Al and Mg
• Near net shape
• Complex parts
• Thin walled
• Rapid die filling
• High cycle rate
• High after-pressure

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Why is the heat loss important?

• May have an effect on the casting if the heat
  loss is high
• Different process parameters
• Different alloys

• May cause casting defects
• Externally solidified crystals
• Cold shut

What is the objective?

• Melt temperature and volume
• Fill time and height
• The metal stream hits the same spot
• Die surface and temperature

• Vary the different process parameters and see
  what effects it have on the heat loss and heat
  transfer
• Achieve reproducible results that can be used in
  the simulation program Magma Soft
• Use results to produce new simulation software?
• Evaluate the response time for different
  thermocouples

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Setup Casting Experiments
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Preliminary Results

• The effect of the hit point for the metal stream
• Thermocouple 3
• Melt temperature 680 ºC
• Die temperature 250 ºC
• Die Surface Roughly polished or polished

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Preliminary Results
Roughly polished
Polished 1000X
Average value

• The effect of die surface
• Thermocouple 10
• Melt temperature 680 ºC
• Die temperature 250 ºC

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Further work with shot cylinder

• Vary the different parameters and look at the
  effects on heat loss and heat transfer
• Increase the logging frequency
• Simulate the filling process using MagmaSoft and
  compare with the experimental results
• Find heat transfer coefficients for the different
  process parameters
• Evaluate the oxide formation during filling by
  using high frequency camera

Casting trails in Porsgrunn

• Planning to carry out casting experiments with
  real HPDC machine
• Use a plug with thermocouples for temperature
  measurements. Up to eight thermocouples can be
  used

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Preliminary conclusion

• The reproducibility is very good when the
  experiments are done with the exact same casting
  conditions.
• The metal stream hit point in shot cylinder has a
  huge impact on the measured temperatures. The die
  surface shows the same tendency.
• The temperature profile further away from the
  filling hole shows a larger variation in the
  measured temperatures. The hit point for the
  metal stream can be the main factor that affects
  this.