Casting Simulations with STAR-Cast Julian Gnz, CD-adapco Need for - - PowerPoint PPT Presentation

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Casting Simulations with STAR-Cast Julian Gnz, CD-adapco Need for - - PowerPoint PPT Presentation

Aug 14, 2023 31 likes •304 views

Casting Simulations with STAR-Cast Julian Gnz, CD-adapco Need for Casting Simulation Processes Market Overview [Mio tons] Permanent Mold Tilt Casting 13,6 38,16 Grey Iron 9 Low Pressure-Casting Ductile Iron High

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SLIDE 1

Casting Simulations

with

STAR-Cast

Julian Gänz, CD-adapco

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SLIDE 2

Need for Casting Simulation

Processes

  • Permanent Mold
  • Tilt –Casting
  • Low Pressure-Casting
  • High Pressure Die

Casting

  • Continuous Casting
  • ...
  • Lost Mold
  • Sand Casting
  • Precision Casting
  • Centrifugal
  • Bridgeman
  • ...

From Modern Casting “2010 world census casting production”

Material Cost/tonne [$] Relative Carbon Steel 550 1 Cast Iron 830 1,51 Aluminium/alloys 2220 4,0 Titanium /alloys 17 000 30,9

38,16 19,4 9 13,6

Market Overview [Mio tons]

Grey Iron Ductile Iron Steel Non Ferrous alloys

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SLIDE 3
  • Variety of processes and materials
  • Sophisticated geometries
  • Simulation can help to meet the different and often contradicting demands

– Requirements

  • Mold filling with solidification
  • Defect Prediction
  • Design tool

Need for Casting Simulation

12000 30000 100000 120000 150000 Tool Cost [$]

From Austin Group 2002

Call for advanced casting processes

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SLIDE 4
  • Best of both worlds

– Provide state of the art of casting simulation solution by combining the engineering experience of two companies which have a long-standing track record in providing CAE solutions and casting processes for over 25 years – Established casting solution STAR-Cast

Strategic Partnership

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SLIDE 5
  • First released in 2009
  • Dedicated design and engineering tool for the casting engineer
  • Core -Capabilities
  • Multiphase
  • Resolution of the molten flow and filling front
  • Model phase change
  • Dedicated material database
  • Dedicated User Interface
  • STAR-CCM+’s state of the art meshing

STAR - Cast

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SLIDE 6
  • Speaking the language of the casting engineer
  • Quickly adaptable to simulation needs

The Process

Geometry

  • Any given CAD data
  • 3D-CAD Modeller

Mesh

  • Fluid /Solid Interfaces
  • Appropriate meshing models

Physics

  • Adapt to simulation goal
  • Expandable

Post processing

  • Transient Postprocessing
  • Criteria functions, defect analysis
  • VOF
  • Isothermal- gating design
  • Thermal - cooling/ solidification
  • Particles/ erosion

Filling

  • Progress of Solidification
  • Influence on flow
  • Misruns and cold shut

Solidification

  • Piston Motion
  • Tilting
  • Rotation

Motion

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SLIDE 7
  • A dedicated Material Database is available in STAR-Cast, pooling

all relevant material information for the casting engineer

Industrial Challenge - Materials

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SLIDE 8
  • Mushy / Slurry Zone

– Transition from liquid to solid leads to partially solidified areas – Carman Kozeny approach

  • Solid - Flow Stop

– Complete stop of flow in solidified areas

Industrial Challenge - Solidification

Liquid Mushy Solid fL= 0.0 fL= 0.3 fL= 1.0

          

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SLIDE 9
  • Deduct additional information about the solidification process

and the overall quality of the cast

  • Gather Temperature gradients, cooling rates and local solidification times
  • Compute criteria functions, such as Niyama or G/v criterion
  • Estimate porosity characteristics

Industrial Challenge - Defect Prediction

centre line porosity Ref: f: Ac Acces ess, s, ST STAR AR-Cast ast 1.10 10

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SLIDE 10
  • Phase selective wall porosities for VOF- Phases

– Capture the venting effect of a porous mold, core ( i.e. Sand, Investment mold)

Industrial Challenge - Porous molds

Porosity to low Calibrated porosity

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SLIDE 11
  • Multi region problem ...

– Complex Geometry – Fluid Cavity – Surrounding Air – Different solids ( mold, cooling iron ..)

... Meshing requirements:

– Easy surface repair – Multi region Volume meshing – Prism layers – Cell count effective meshing in thin areas

Industrial Challenge - Complexity

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SLIDE 12

Investment Casting: Shell generation

  • For precision casting

– Dipping a wax model into a ceramic based slurry – Ceramic slurry dries and builds the mold for the casting – Wax is removed in an autoclave Automatic shell mold generation

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SLIDE 13
  • Shell mold generator

– Mimics a manufacturing process – Based on local curvature

Investment Casting: Shell generation

Investment Casting

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SLIDE 14
  • Challenges in Investment Casting

– Thin-walled components with designs at the limit of producibility – Late design freeze, thus shorter development cycles – New materials – New processes

Investment Casting

Courtesy of Access e.V.

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SLIDE 15
  • Answers Engineers are seeking

– Sensitivity analyses for process parameters, running and gating system – Geometrical parameter studies – Enhancement and conservation of raw materials and reduction of overall manufacturing cost

Investment Casting

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SLIDE 16

Example of a mould-filling optimization

Initial setup Optimized setup Sprue cup Crucible

Courtesy of Access e.V. & CD-adapco

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SLIDE 17

Example of a mold-filling optimization

1 7 Non-optimized Optimized Simulations show that in a non-optimized distributor the liquid metal keeps rotating in the distributor for a longer time before entering the sprue

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SLIDE 18
  • What kind of Defects are of relevance for Investment

Castings:

  • Misruns
  • Porosity
  • Freckles
  • Stray grain formation
  • Segregation
  • Hot tearing

Investment Casting

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SLIDE 19

Predictions of misruns in a gravity-cast LPT blade

1 9 Shell Mould Runner Blade

Schematic diagram of the process Polyhedral Volume Mesh

Sprue Inlet

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SLIDE 20

Comparison of simulation and casting trials

Gravity casting, Access TechCenter

Value of secondary dendrite arm spacing was obtained from microstructure measurements

Magnitude of velocity Temperature

Courtesy of Access e.V. & CD-adapco

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SLIDE 21

DS/DX Castings: Stray Grain Formation

  • Stray grains form when

corners of the part solidify and there is no connection to the main solidification front.

Marked corner will show a stray grain

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SLIDE 22
  • Enhance accuracy, robustness and ease of use for a wider range
  • f casting processes
  • Include further solidification models

– Ductile Iron, Grey Iron – Composite castings

  • Next STAR-Cast release:

» Fully Based on STAR-CCM+

Looking ahead

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SLIDE 23
  • Latest solver and meshing capabilities
  • Modern and easy handling
  • All the physics to carry out casting simulations

– Material Database – Shell mold generator – Defect prediction

  • Add on module to STAR-CCM+

STAR-Cast embedded in STAR-CCM+ : v8.02

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SLIDE 24
  • Dedicated mesher for investment

casting

– Automated Region generation – Prism Layer + Embedded Thin Mesh in thin areas

  • Streamlined Workflow
  • Simple set of input variables

STAR-Cast embedded in STAR-CCM+: 8.04

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SLIDE 25
  • Process driven GUI for casting applications:

– New approach to STAR-CCM+ – GUI adapts to the selected casting process – “Best Practices” are stored – High level of automation – Guide the user through process

STAR-Cast embedded in STAR-CCM+ : Outlook

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SLIDE 26
  • Concept
  • Expose only required functionalities
  • Use casting terminology
  • Shorten the learning curve
  • “Conditions”: reusable
  • Input is stored in an XML file

STAR-Cast embedded in STAR-CCM+ : Outlook

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SLIDE 27

Casting Simulations

with

STAR-Cast

Julian Gänz, CD-adapco