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BIW Design

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BIW Design Dos and Donts

Spots to be loaded in Shear

The Material Thickness (All included) < ~4.00mm

The Difference between the Thickness of weldingpanels : < 25%

Check Distance between Two Consecutive spots Panel to be designed to have Max. Stretching.

Thinning of Panels : ~10%

Part to be designed to have minimum number of Dies.

Panels to split in a manner to utilize maximum Steel

Generally for big panels 60% utilization is Good

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BIW Design Dos and Donts

Sufficient provision of Holes and Cutouts forAir Escape and Paint Drain.

Weight Reduction Cutouts should be clubbed

with the Access holes / Cutouts and Drains.

Add Bird Beaks, Ribs to contain Spring back

Avoid Stretch Flanges

Corner Radii Min 2.5 * Depth (e.g. Ingress-Egress issue for Body Side)

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Panel Design Guidelines

Should not be odd and big in shape and size;

handling issues. Size as per manufacturing facility available.

Panel Split for

maximum utilization of material,

criticality of the area and manufacturing facilityavailable.

Generally for bigger panels 60% of materialutilization is good.

Sufficiently stretched Load Considerations.

No area left un-stretched In areas which are mostly of geometrical

continuity, Stiffener beads to be provided.

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A maximum of 15% stretching is allowed in steel sheet

drawing. Thinning < 10%.

Depth of draw can be achieved by providing steps.

Internal features (Local depressions) should have radiusas big as possible.

For deep draw panels, the number of draw should be as per manufacturing

guidelines.

Avoid providing any feature, in other than die tip angle, as

this may lead to cam operation. If possible the trim edges of internal features should have

some radius. (Sharp edge tools get damage soon)

Panel Design Guidelines

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Thickness of panels should be chosen as per the application.

Do not increase the thickness of complete panel.Local reinforcement to be added as an when required.

Latest trend is of Tailored blank.

To reduce the part weight, areas of least stress should betrimmed (Pockets created).

The weight reduction pockets should be tried and clubbedfor Tooling Access Holes, Air vent and Paint drain.

Panel Design Guidelines

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Panel Joinery Guidelines

Load on Spot weld to be in Sheer. Flange width to be as per manufacturing requirements

(Tooling). For general purpose, 18mm flat is consideredOK.

There should not be more than three panel thickness stack

for spot weld. CO2 weld and Brazing to be avoided.

Joinery should be designed in a manner where no spot ison the A- class Surface.

The joinery should be such that it counters the tolerance

stack. Joinery should have sliding contact i.e. No joinery to be in

locking condition.

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For bigger assemblies in docking - design gap should bekept. For Example between Side assembly and

Underbody assembly, 1.00mm design gap is OK.

The joinery to be sequenced to avoid any lockingsituation.

There should not be a difference of more than 50%between two joining panels.

To get better Spot strength, total material stack shouldbe 4 to 4.5mm.

The Serviceability aspects should be kept in

consideration.

Panel Joinery Guidelines

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BIW Manufacturing Process

Body ShopPress Shop Paint Shop Trim Line Final Assy

Form the panels

Presses

Dies

Checking

Fixtures

Assemble the

panels

Fixtures

Welding Guns

Checking

Fixtures

Metal

Finishing tools

Conveyers

Painting Body

Pre-treatment

Oven Baking

Finishing

Painting

Oven Baking

Inspection

Body Trimming

I/P Fitment

Seat Fitment

Glasses

Trim

Carpets

Vehicle Roll-

down

Power Train

Suspension

Steering

Fuel System

Brakes

AlignmentsTesting

Inspection

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Formability Problems in Panels

Fracturing Buckling and Wrinkling

Shape Distortion

Oil Canning Undesirable Surface Textures (Orange Peel,

Luder Lines or Stretcher Lines, Spangles etc)

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Steel used in BIW

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Properties vary for the same material

From Supplier to Supplier From heat to heat

From coil to coil

From angle to angle with the rolling direction From one end of coil to other end of coil

From one edge of coil to other

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Design-Manufacture

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Design-Manufacture

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Exploded View of utomobile Body Panels

Floor Panel Body Side Panel

Cowl Panel

Door Inner Panel

Rear Floor Panel

B pillar inner

Tail Gate panel

Rear Long Member

Bonnet Inner

Hinge reinforcement

Roof bow rearRoof bow middle

Panel A pillarInner

Shot gun panel

HingeReinforcement

Sill Rear Inner

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Thank You