Calibration and Simulation of the Automotive E-Coat Dipping Process - - PowerPoint PPT Presentation

Calibration and Simulation of the Automotive E-Coat Dipping Process in STAR-CCM+ (V8.02) Frank Pfluger, Klaus Wechsler CD-adapco

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How Virtual Manufacturing Can Support Digital Product Development – Better Corrosion Protection by E-Coat Simulation with STAR-CCM+

Recent progress in simulation methods for the manufacturing industry has reduced the need for expensive test hardware. Using simulation tools earlier in the product development process, typically at the design stage, helps optimizing both the product and the process while ensuring that manufacturing quality and cost requirements are met. STAR-CCM+ 8.02 simulation process provides an improved workflow from CAD-data meshing to E-coat deposition, including modeling of fill and drain behaviors in automotive paint shops. Simulation results provide the design engineer with answers to questions such as ´is the paint thick enough in all the cavities?´ or ´is there a corrosion risk based on air bubbles or paint ponds?´ regarding the E-coat dipping process. For more information have a look at : From CAD Data to E-coat thickness: Learn the special knowledge to do it with STAR-CCM+ Klaus Wechsler – CD-adapcoTAR-CCM+ Klaus Wechsler –

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Overview of Simulation Activities Driven by Hardware Reduced Platform Development

Published at Daimler EDM/CAE Forum

Using CD-adapco SW

Paint Shop Simulation

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The E-Coat Deposition Process provides basic corrosion protection

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Understanding the E-Coat Deposition Process

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Principle of E-Coat Deposition Process

BIW= Cathode

Electrolyte BIW=Cathode

• Paint Deposition on all BIW-surfaces contacted to electrolyte
• Paint thickness (µm) can be measured after curing in oven
• Thickness varies from 0-Max according to applied Voltage,

Current-Flow, Process-Time, Throw-Power of Paint System,..

• Parametric Deposition Model is established in STAR-

CCM+ (Version 8.02)

• Will be 20 times faster than earlier Version
• Parameters have to be calibrated according to individual

Paint Systems .

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Adopting STAR-CCM+ E-Coat Modell Parameters until Measured Test Case Thickness Fits Best to Simulated Thickness of Test Case Anodes Calibration Geometries in Tank (Cathode)

50 100 150 200 250 60 120 180 240 Potential in V Time in s

Voltage Pattern for Calibration Geometries

Comparing Measured and Simulated E-Coat Thickness inside Calibration Geometries

Test Case

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Calibration Example with Good Throw-Power

Visualization of Paint Deposition Inside Calibration Geometries

Video

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Calibration Example with Bad Throw-Power

Visualization of Paint Deposition Inside Calibration Geometries

Video

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Visualization of Paint Growth in Calibration Pipes

Mouth (M): Deposition starts simultaneously for 0.5m, 1.0m and 1.5 m Pipe Length Central Inner Point (CIP) of Pipes: Different Time Offsets for E-Coat deposition

E-Coat Thickness (µm)

0.5 m Pipe: CIP Deposition starts after 60sec 1.0 m Pipe: CIP Deposition starts after 180 sec 1.5 m Pipe: CIP has no deposition within 240 sec

M M M

Deposition Time (s) Outer side of pipe starts here

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Visualization of Paint Growth in Calibration Pipes Focus of Calibration:

Final E-coat Thickness

(Important For Corrosion Protection)

E-Coat Thickness (µm)

CIP 0,5m CIP 1,0m CIP 1,5m

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Automotive example provided by CrabCAD (Open Source CAD)

• Ca. 17 Million trimmed mesh cells created by STAR-CCM+
• Ca. 81 m² surface area for e-coat deposition
• Ca. 2.5 hours computation time on 16 CPU´s (8 cores/CPU) for a

E-coat deposition time of about 200 sec

Demonstration of STAR-CCM+ E-Coat Simulation Capabilities for BIW (Version 8.02)

Demonstration of E-Coat Simulation Demonstration of E-Coat Simulation

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E-Coat Deposition Process

Demonstration of E-Coat Simulation

Looking inside a cavity with poor E-Coat thickness based on limited access for current flow

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E-Coat Deposition Process

Walking through the cavities: Different e-coat thickness based on limitation of electric current flow inside the structure of the car body.

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Example of E-coat Thickness Inside Cavities

Simulation is used for optimization of corrosion protection

Simulation allows walk through all cavities. Critical surfaces with reduced corrosion protection can be identified.

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Example of E-coat Thickness Inside Cavities

Simulation is used for optimization of corrosion protection Holes are to small for sufficient e-coat thickness

Bigger Diameter or more holes are necessary for corrosion protection

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Example of E-coat Thickness Inside Cavities

Simulation is used for optimization of corrosion protection Holes have influence on E-Coat thickness

Bigger Diameter or more holes improve corrosion protection

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Simulation of Dipping in (1sec=1h on 32 CPU, 8 Cores/CPU)

Remaining Air Bubbles Avoid E-Coat Film Building

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Simulation of Dipping in (1sec=1h on 32 CPU, 8 Cores/CPU)

Visualizing the Movement of Air Bubbles

Final Position in E-coating should be without air bubbles. Simulation gives information for possitioning of bleeding holes.

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Simulation of Dipping out:(1sec=1h on 32 CPU, 8 Cores/CPU)

(Remaining Ponds Contaminate Next Dipping Process Step)

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Details of Dipping out Simulation:

Remaining Ponds Contaminate next Dipping Process Step

Page 22 E-Coat Simulation calculates Paint Thickness

• n all surfaces (ca 80 sqm)

Demonstrating Fill and Drain Simulation Air-Bubbles (red): Avoiding E-coating Puddles (blue): Contaminating next Dipping Tank

Electrolyte BIW=Cathode

Mercedes SL:

Size and position of fill&drain and e-coat holes/openings had been optimized by dipping and e-coat deposition simulation Source: Internet

Overview of Paint Shop Simulation (1/2)

Page 23 Simulation of Dipping Forces on Car Body Parts (BIW) Simulation of Thermal Heat up and Cool down, Paint Curing

dp

Source: University

• f Korea

Source: Bracht Roller KIT Ppuplishing

Overview of Paint Shop Simulation (2/2)