BIW stands for body in white. It refers to the stage in automotive manufacturing where the vehicle's sheet metal components have been welded or bonded together to form the basic structural shell. At this stage, the frame is complete but lacks doors, glass, powertrain, electronics, and paint. Engineers use this bare structure to evaluate chassis stiffness, crashworthiness, and overall structural integrity.
We need to run a torsional rigidity test on the new EV platform's BIW before finalizing the suspension mounting points.
The term originates from early manufacturing days when bare wooden or metal bodies were painted white to highlight defects before the final color was applied.
Related terms
Body in white
The welded sheet metal shell of a vehicle before painting, trim, or powertrain installation.
Body in black
The bare structural shell of a vehicle constructed entirely from carbon fiber composites.
Unibody
A unibody is a vehicle construction method where the floor pan and body shell are welded into a single load-bearing structure.