What is BIW and what processes are involved in its manufacturing?

BIW (Body-in-White) refers to the vehicle body structure before painting and trim installation. The term originates from the white primer used historically. BIW manufacturing involves stamping individual panels from sheet metal, then joining them through welding (primarily resistance spot welding), adhesive bonding, and mechanical fastening. The BIW provides structural integrity, crash protection, and mounting points for all vehicle systems. Modern BIW uses multiple materials including steel grades, aluminum, and composites to optimize weight and performance.