In the automotive industry, joining panels in the Body in White (BIW) assembly involves various processes to create a structurally sound and durable vehicle body. Here are some common processes used for BIW panel joining:
Spot Welding:
- This is a widely used process where two or more metal sheets are joined by creating a series of overlapping welds using an electric current.
MIG/MAG Welding (Metal Inert Gas/Metal Active Gas):
- Similar to spot welding, MIG/MAG welding uses a continuous solid wire electrode and a shielding gas to join metal panels. It is suitable for both thin and thick materials.
TIG Welding (Tungsten Inert Gas):
- TIG welding uses a non-consumable tungsten electrode and a separate filler material. It is often used for precision welding of thin materials.
Resistance Spot Welding:
- This process involves passing an electric current through the panels at the point of contact, creating resistance and subsequently generating heat to melt and fuse the metals.
Adhesive Bonding:
- High-strength adhesives are used to bond panels together. This process is often used in conjunction with other joining methods to enhance structural integrity and reduce weight.
Riveting:
- Various types of rivets, such as self-piercing rivets or pulling rivets, are used to join panels together. These can be applied using automated systems.
Self-Clinching Fasteners:
- These are fasteners designed to be pressed into pre-drilled holes in the panels. They provide a strong and reliable connection.
Screw Joints:
- Screws are used to join panels together. This method is often employed for removable or adjustable components in the BIW assembly.
Bolting:
- Bolts and nuts are used to connect panels in some applications. This method allows for disassembly and reassembly if needed.
Folding/Tab Joint:
- Panels are designed with tabs or folds that interlock, creating a joint. This method can provide additional strength and stiffness.
Each joining method has its advantages and is chosen based on factors such as material properties, design requirements, production efficiency, and cost considerations. Automotive manufacturers often use a combination of these processes to achieve the desired results in BIW assembly.
1. Spot Welding
Spot welding is indeed a thermal joining process commonly used in the manufacturing industry to join two or more metal sheets or panels. The process relies on the principles of resistance heating.
Spot welding is commonly used in the automotive industry for joining sheet metal parts in the manufacturing of car bodies. It is a fast and efficient process that can produce high-quality welds with minimal distortion to the surrounding material. The process is well-suited for materials with good electrical conductivity, such as low carbon steels and certain alloys.
There are various guns to do spot welding but most commonly used guns are X – TYPE and C – TYPE gun. X guns are also known as scissors or pinch gun. These guns are selected on the basis of location of gun mount,tooling access and the geometry of the panel. X-Gun or C-Guns can different shapes of die post as per the requirement.
Mentioned area is known as die post of the gun.
X GUN :
In this gun actuator is parallel to the weld plane and and actuates about a pivot.
X type guns are used where accessibility is constraint.
C GUN :
C-type or straight action gun actuates perpendicular to the plane and in line with the weld.
GUN STROKES :
Working Condition: That condition when both electrodes on gun are touching the panel while doing spot welding is called as Working Condition.
Semi opening condition or intermediate stroke: After completing one stroke, gun moves to next spot without opening completely is knownas intermediate stroke or semi opening. This opening may differ as per the requirement.
Full Stroke or Full opening : it is the maximum open condition of moving electrodes of the gun.
Basics while considering a gun :
- Preferably Fixed electrode should be visible to the operator.
- Gun should have good reach-ability to all spots.
- As much as possible same gun should be used for maximum no. of spots.
- Tip wear out condition (preferably 5 mm) should be considered while designing the tool.
Self piercing Rivet(SPR) :
SPR- Self-piercing riveting is a cold mechanical fastening technique for joining of two or sheet metals or panels. For joining , the rivet is driven into the matel at a controlled force, piercing the panels, Then rivet radially expands into the bottom layer,due ti the shape of die, forming a mechanical interlock.
This process is quite helpful in joining of aluminium panels.
MIG WELDING(Metal Inert Gas) :
Metal inert gas welding or MIG Welding is based on the electric arc welding process where completion of an electric circuit between positive and negative poles creates an electric arc , which generates tremendous heat permitting the fusion welding of metals.
GLUE GUN :
Glue guns are used for metering of sealentso or adhesive bonds.
adhesive bonding and sealing are used for various applications in the modern automotive induastry.