calibration and simulation of the automotive e-coat...

Calibration and Simulation of theAutomotive E-Coat Dipping Process in

STAR-CCM+ (V8.02)Frank Pfluger, Klaus Wechsler

CD-adapco

How Virtual Manufacturing Can Support Digital ProductDevelopment – Better Corrosion Protection by E-CoatSimulation with STAR-CCM+

Recent progress in simulation methods for the manufacturing industry has reduced the need forexpensive test hardware. Using simulation tools earlier in the product development process, typically atthe design stage, helps optimizing both the product and the process while ensuring that manufacturingquality and cost requirements are met.

STAR-CCM+ 8.02 simulation process provides an improved workflow from CAD-data meshing to E-coatdeposition, including modeling of fill and drain behaviors in automotive paint shops. Simulation resultsprovide the design engineer with answers to questions such as ´is the paint thick enough in all thecavities?´ or ´is there a corrosion risk based on air bubbles or paint ponds?´ regarding the E-coat dippingprocess.

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 –

Overview of Simulation Activities Driven byHardware Reduced Platform Development

Published atDaimler EDM/CAE Forum

UsingCD-adapco

SW

Paint ShopSimulation

The E-Coat Deposition Processprovides basic corrosion protection

Understanding the E-Coat Deposition Process

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 .

Adopting STAR-CCM+ E-Coat Modell Parameters untilMeasured Test Case Thickness Fits Best to SimulatedThickness of Test Case

Anodes

CalibrationGeometries in Tank(Cathode)

0

50

100

150

200

250

0 60 120 180 240

Pote

ntia

l in

V

Time in s

Voltage Patternfor CalibrationGeometries

Comparing Measured andSimulated E-Coat Thicknessinside Calibration Geometries

Test Case

Calibration Example with Good Throw-PowerVisualization of Paint Deposition Inside Calibration Geometries

Video

Calibration Example with Bad Throw-PowerVisualization of Paint Deposition Inside Calibration Geometries

Video

Visualization of Paint Growth in Calibration PipesMouth (M): Deposition starts simultaneously for 0.5m, 1.0m and 1.5 m Pipe LengthCentral Inner Point (CIP) of Pipes: Different Time Offsets for E-Coat deposition

E-Coat Thickness (µm)0.5 m Pipe:

CIP Deposition startsafter 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 pipestarts here

Visualization of Paint Growth in Calibration Pipes

Focus ofCalibration:Final E-coatThickness(ImportantFor CorrosionProtection)

E-Coat Thickness (µm)

CIP 0,5mCIP 1,0m

CIP 1,5m

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 depositionCa. 2.5 hours computation time on 16 CPU´s (8 cores/CPU) for aE-coat deposition time of about 200 sec

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

Demonstration ofE-Coat Simulation


E-Coat Deposition Process


Looking inside a cavity with poorE-Coat thickness based onlimited access for current flow

E-Coat Deposition Process

Walking through the cavities:Different e-coat thickness based onlimitation of electric current flowinside the structure of the car body.

Example of E-coat Thickness Inside CavitiesSimulation is used for optimization of corrosion protection

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


Holes are to small for sufficient e-coat thicknessBigger Diameter or more holes are necessary for corrosion protection


Holes have influence on E-Coat thicknessBigger Diameter or more holes improve corrosion protection

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

Remaining Air Bubbles Avoid E-Coat Film Building

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

Visualizing the Movement of Air Bubbles

Final Position in E-coating shouldbe without air bubbles.Simulation gives information forpossitioning of bleeding holes.

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

(Remaining Ponds Contaminate Next Dipping Process Step)

Details of Dipping out Simulation:Remaining Ponds Contaminate next Dipping Process Step

E-Coat Simulationcalculates Paint Thicknesson all surfaces (ca 80 sqm)

Demonstrating Fill and Drain SimulationAir-Bubbles (red): Avoiding E-coatingPuddles (blue): Contaminating next Dipping Tank

ElectrolyteBIW=Cathode

Mercedes SL:Size and position of fill&drain and e-coatholes/openings had been optimized bydipping and e-coat deposition simulation

Source: Internet

Overview of Paint Shop Simulation (1/2)

Simulation ofDipping Forces on Car Body Parts (BIW)

Simulation of Thermal Heat up and Cool down,Paint Curing

dp

Source: Universityof Korea

Source: Bracht Roller KITPpuplishing

Overview of Paint Shop Simulation (2/2)

calibration and simulation of the automotive e-coat...

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