BIW Design PDF

BIW Design
BIW Design Dos and Donts
Spots to be loaded in Shear

The Material Thickness (All included) < ~4.00mm
The Difference between the Thickness of welding
panels : < 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
BIW Design Dos and Donts
Sufficient provision of Holes and Cutouts for

Air 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)
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 facility
available.
Generally for bigger panels 60% of material
utilization is good.
Sufficiently stretched Load Considerations.
No area left un-stretched
In areas which are mostly of geometrical
continuity, Stiffener beads to be provided.
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 radius
as 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)
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 be

trimmed (Pockets created).
The weight reduction pockets should be tried and clubbed

for Tooling Access Holes, Air vent and Paint drain.
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 considered
OK.
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 is
on 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.
Panel Joinery Guidelines
For bigger assemblies in docking - design gap should be
kept. For Example between Side assembly and
Underbody assembly, 1.00mm design gap is OK.
The joinery to be sequenced to avoid any locking
situation.
There should not be a difference of more than 50%
between two joining panels.
To get better Spot strength, total material stack should
be 4 to 4.5mm.
The Serviceability aspects should be kept in
consideration.
BIW Manufacturing Process
Press Shop Body Shop Paint Shop Trim Line Final Assy
Form the panels Assemble the Painting Body Body Trimming Vehicle Roll-
panels down
Presses Pre-treatment I/P Fitment
Fixtures Power Train
Dies Oven Baking Seat Fitment
Welding Guns Suspension
Checking Finishing Glasses
Fixtures Checking Steering
Painting Trim
Fixtures
Fuel System
Oven Baking Carpets
Metal
Brakes
Finishing tools Inspection
Alignments
Conveyers
Testing
Inspection
Formability Problems in Panels
Fracturing
Buckling and Wrinkling
Shape Distortion
Oil Canning
Undesirable Surface Textures (Orange Peel,
Luder Lines or Stretcher Lines, Spangles etc)
Properties affecting the formability of material
r value Work Hardening Coefficient

n value Resistance to thinning
UTS
Yield Point Elongation
Uniform Elongation
Total Elongation
Yield Strength
Hardness
Punch Velocity
Lubrication
Chemistry
Steel used in BIW
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
Design-Manufacture
Design-Manufacture
Exploded View of Automobile Body Panels
Tail Gate panel

Door Inner Panel Roof bow middle Roof bow rear
Panel A pillar
Inner Sill Rear Inner
Hinge
Reinforcement
Rear Long Member

Shot gun panel
Bonnet Inner Rear Floor Panel
Cowl Panel
Hinge reinforcement
Floor Panel B pillar inner Body Side Panel
Thank You

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BIW Design

BIW Design Dos and Donts

Spots to be loaded in Shear

Sufficient provision of Holes and Cutouts for

To reduce the part weight, areas of least stress should be

The weight reduction pockets should be tried and clubbed

Load on Spot weld to be in Sheer.

r value Work Hardening Coefficient

From Supplier to Supplier

Tail Gate panel

Rear Long Member

Bonnet Inner Rear Floor Panel

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