AUTOMOTIVE BIW TOOLING: THE BASICS EVERY DESIGN ENGINEER NEEDS TO KNOW
Body In White (BIW) is a term used to refer to the base body of the car including the doors, hooks, and deck lids that have been put together before the addition of components such as chassis, motor, and trim level parts such as windshields, seats, upholstery, electronics, etc.
At the very fundamental level, BIW provides the required shape and structure for integrating the aforementioned remaining aspects.
BIW tooling is the process of defining the geometry of a BIW body through the welding of metal following by testing and analytics. It is carried out with various tooling techniques such as welding and machining fixtures, press tools, SPMs, testing tools, etc.
Overall, the end goal of the tooling process is to manufacture a complete body in white. The body needs to be well-tested for its function of being the structure on which everything else will be put together. Furthermore, the body shape will eventually be a significant factor in determining the geometrical aesthetics of the vehicle.
BIW tooling is usually executed with a combination of software to help you make design decisions and tools in the factory unit that facilitate the execution of the design.
At a software level, CAD, UGNX, and Office are some of the solutions used. However, the domains of Automotive BIW tooling usually arise from the tooling steps required to manufacture the body.
It's worth noting that these steps do not necessarily follow a particular order, and different aspects may be needed to be executed based on the requirement.
Stamping is the process of cutting the metal into different parts. A variety of tools are used to carry out the stamping process. Soft dies are utilized for thin/soft metal sheets so that their rigidity is not hampered, while hard dies are used for harder variants of the metal.
Hydraulic and pneumatic dies are used as well, depending on the force required to cut the metal, with hydraulic dies serving the purpose of high-force metal cutting or drilling of holes.
Welding, at the most basic level, is the process of joining the different parts created from the stamping process to get the desired initial shape fo the body. In design engineering, welding ranges from manual welding lines to semi-automated ones to robotic welding lines, which are operated by robots with minimal human intervention.
The Special Purpose Machines (SPMs) are used for specific processes such as drilling and machining - using controlled material-removal to reach the desired shape.
Before the entire BIW process is executed, several quality parameters need to be defined to ensure a baseline of quality in the results. The quality check process involves the assessment of the BIW tooling outcomes with the initially-defined parameters.
Inspection gauges assist with measurement of the dimensions and ensure that the different parts of the body meet the minimum and maximum requirements concerning thickness, length, breadth, etc.
The Testing SPMs help to check some of the functional outcomes. For example, you can use SPMs to ensure there's no leakage in the fuel tank.
At a conceptual level, a fixture is an instrument that acts as a placeholder for the material to be welded using the 3-2-1 or the six-point location principle. Applying the 3-2-1 principle ensures that the movement of the material within the fixture is constrained along all three dimensions of space.
The term 3-2-1 arises from the six locating points used for constraining the movement - 3 pins in the base plate, 2 pins in the vertical plane, and 1 pin along the third plane (which is at 90 degrees to other two planes).
A typical welding fixture usually has several units combined to hold the entire car panel. It is mounted on a base unit. The essential function of the fixture is to provide stability and support for the various parts of being welded together.
If such stability and support are missing, then there are potential distortions that may arise from the welding process, thereby resulting in a dissatisfactory output. Stability, light but firm clamping, placement of clamping elements are all key aspects that should be kept in mind for executing the welding process.
Fixtures are of various types:
BIW fixtures are one of the most vital aspects of the tooling process.
Firstly, they help ensure that the welding process meets the pre-defined standards of high-quality. They provide the necessary support and stability to avoid distortions in the welding process, which can often lead to expensive iterations.
Secondly, BIW fixtures help manufacturers achieve efficient productivity, desired dimensions of the body, and increased productivity in the entire process by reducing the average number of iterations.
Ultimately, if design engineers and manufacturing planners are working together, even a minor distortion or a late collision can lead to significant amounts of time and effort pilferage.
BIW fixtures serve as a prevention mechanism, but efficient fixture planning for the complete product lifecycle using various software tools can be used to design, model, and simulate fixtures that can reduce lead-time. This will save engineers time, money, and effort through reduced uncertainty.
Various projects are being pursued to design, produce, and validate fixtures that can secure and stabilize different aspects of the manufacturing processes.
The modularity of BIW fixtures is one of the essential parameters of such attempts. Furthermore, efforts are being made to use integrate elements such as sensors and actuating signals for realistic and large-scale modeling of fixture behavior.
To get an in-depth understanding of Automotive Body In White (BIW) tooling, check out our courses on Skill-Lync today.
The Automotive Sheet Metal Design course provides an outline of the current Body in White (BIW) component design factors and detailed explanations about their significance to part function, cost, and reliability.
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