Introduction
Modern cars are a combination of subsystems and components, including essential engine components, and each of them is designed to be efficient, safe, and durable. At the center of it is an automotive metal forming: a gargantuan branch of engineering that deals with the shaping, cutting, welding, and polishing etc of metals into the body, powertrain, and other components of the car.
In this paper, I propose to discuss the characteristics of automotive metal fabrication and its processes, materials, design factors, and trends that have impacted automotive components in the industry. These factors are important to every practitioner who is involved in designing, engineering, manufacturing, or sourcing vehicles.
What is Automotive Metal Fabrication?
Automotive metal fabrication is the process of converting a metal in its primary or semi-finished form such as sheets, tubes, bars or billets and turning it into a part that is to be used in automobiles. This encompasses operations such as cutting, shaping, assembling, and even polishing of the final product. It mainly deals with the controlled removal of material from metals to achieve predetermined geometric dimensions, shape, mechanical properties, accuracy and surface finish.
It is impossible to overestimate the role of metal fabrication in automotive industry. Metals are the most suitable materials for constructing chassis and body frames because they are strong and rigid to ensure safety of the passengers and stability of the vehicle. Metals also offer the required durability and heat resistance for powertrain and exhaust systems. Also, the ability to shape metal allows for aerodynamic design and compactness of internal structures. Nevertheless, metals remain the basic materials for the construction of essential components of an automobile, and, thus, mastery of metalworking is essential in the automotive industry.
Common Materials in Automotive Fabrication
| Material | Strength (MPa) | Corrosion Resistance | Workability (Hardness) | Density (g/cm³) | Electrical/Thermal Conductivity (W/m·K) | Cost | Application |
| Steel | 400-600 | Medium | 150-200 HB | 7.85 | 45 | $ | Body panels, structural reinforcements, chassis. |
| Stainless Steel | 500-800 | Excellent | 170-220 HB | 7.85 | 16 | $$ | Exhaust systems (mufflers, pipes, catalytic converters), trim, fasteners. |
| Cold Rolled Steel | 450-700 | Medium | 140-180 HB | 7.85 | 40 | $ | Body, chassis, and other structural components. |
| Galvanized Steel | 350-500 | Good | 120-160 HB | 7.85 | 45 | $$ | External body parts (body shells, doors, protective panels). |
| Copper | 210-250 | Good | 50-70 HB | 8.96 | 398 | $$$ | Electrical wiring, heat exchangers, radiators. |
| Titanium | 900-1100 | Excellent | 160-200 HB | 4.43 | 22 | $$$ | High-performance applications (connecting rods, exhaust parts, aerospace). |
| Magnesium | 200-300 | Medium | 50-60 HB | 1.74 | 156 | $$ | Lightweight parts (body frame, wheels, etc.). |
Note: the numbers given are average and can be influenced by the exact composition of the alloy, the method of production and treatment. Cost estimates are relative and depend on the market conditions.
Key Metal Fabrication Processes for Automotive
A diverse range of processes is utilized to transform these materials into finished automotive parts. The selection depends on factors like the material type, part complexity, required precision, production volume, and cost targets.
Cutting
Cutting is usually the first operation, where the material is brought to the near net shape or size required for the next operation. Primary methods include:
Laser Cutting: This is a process that involves the use of a high energy laser beam to cut through the material through heating and burning or vaporizing it. It is characterized by high accuracy, smooth cutting edges, ability to cut shapes and curves and compatibility with different metals and thicknesses. It is mostly applied in prototyping, mid range production and for applications that require cutting intricate shapes in thin metals including AHSS.
Plasma Cutting: It employs a stream of ionized gas at high temperatures to melt the material and then to remove it by blowing. Faster than laser cutting for thicker materials such as steel and aluminum but is less accurate and has a larger heat affected zone (HAZ). Often used in cutting of thick plates for structural members.
Waterjet Cutting: This is a cutting technique that involves use of high pressure water jet that may be blended with an abrasive garnet. It is a cold cutting process and as such does not produce a heat affected zone thus suitable for heat sensitive materials or thick sections. Highly versatile across nearly all materials but typically slower than laser or plasma.
Shearing: A process of cutting sheet or plate metal by means of blades especially for straight line cutting. Suitable for high production volume blanking processes due to its fast and cost-effective nature.
Stamping/Pressing
Stamping is a high volume process that is widely used in manufacturing of automotive parts especially body and structural parts from sheet metal. It entails positioning a thin metal sheet between two tool steel tools known as dies in a mechanical or hydraulic press. The press exerts a lot of pressure to either cut, shape or form the metal in question.
Blanking/Piercing: It is a process of cutting the desired shapes or holes in the sheet metal.
Bending/Flanging: Creating angles or edges.
Deep Drawing: The process of converting sheet metal into cup shaped or box shaped parts such as oil pans, fuel tanks, complex body panels etc by pressing the metal into a die with the help of a punch.
Progressive Die Stamping: This is a process in which a strip of metal coil passes through a single die containing several stations where different operations are performed in a continuous manner. Highly efficient for complex, high-volume small to medium parts.
Transfer Die Stamping: The individual parts are transferred mechanically from one die station to another. Applicable for large parts or operations that cannot be grouped in a progressive die.
Bending and Forming
These processes work on metal, mostly sheet or tube, including sheet metal bending, to change its form but does not involve the removal of material.
Press Braking: Involves the use of a hydraulic or mechanical press with a punch and die to form a specific bend on the sheet metal. Suitable for making angles and channels in brackets, enclosures and structural members for low volume or prototype production.
Roll Forming: Passes the metal coil through a set of rolls that successively shape the metal into the final cross-sectional shape. Ideal for creating long parts with uniform thickness, for example, car frames, door sills, or molding strips.
Tube Bending: Uses equipment such as the mandrel benders to bend tubes or pipes to the desired angles and radii without flattening them which is useful in exhaust systems, fluid conveyance, and structural members.
Casting and Forging
Although casting and forging are usually thought to be distinct from fabrication that is based on sheet or plate, they are important metalworking processes for particular automotive parts that need bulk shape and are crucial for any metal fab project or high strength.
Casting: This is a process whereby molten metal is poured into a mold and allowed to cool and solidify into the required shape. Techniques such as die casting (high pressure and reusable molds) are employed for intricate aluminum or magnesium parts including engine blocks, transmission cases and housings. Sand casting is used for large and relatively less accurate parts.
Forging: The process of shaping the metal by applying pressure on it with the help of dies. Hot forging increases the ductility of the material while cold forging increases the strength of the material and the surface finish. Forging is used to create parts with high strength and fatigue limits, making it suitable for applications such as crankshafts, connecting rods, suspension arms, gears, etc.
Machining
Machining operations are those in which material is cut away by a cutting tool to provide the required shape, size, and surface finish. CNC machining automates these processes for high accuracy and repeatability of the processes involved in the production of the parts.
Milling: It is a process that employs a rotating multiple tooth cutter to eliminate material from a workpiece. It is used to create flat surfaces, slots, pockets and other complex shapes.
Turning: Rotates the workpiece against a stationary cutting tool. Employed in the production of cylindrical items, tapers, and threads, for example, shafts, axles, and valve parts.
Drilling/Boring/Reaming: This process is used to make holes or to refine the size of the holes to the required size. Machining is critical for any part that is to be used in an engine, transmission, braking system, or any part that has to fit into another part. It is also applied to the finishing of features on castings, forgings or stamped parts.
Welding and Joining
These processes involve joining of several fabricated parts to form larger sub-assemblies or the actual structure of the vehicle.
Resistance Spot Welding (RSW): The most widely used process for joining of sheet metal panels in automotive body manufacturing. It employs the use of electrical resistance between electrodes to heat and melt specific areas to create fuses. Fast and suitable for automation.
MIG Welding (Gas Metal Arc Welding – GMAW): The electrode is a continuously fed wire and the process is protected by a shielding gas. Versatile, relatively fast, and suitable for various metals and thicknesses. It is common for chassis, frames, and exhaust systems.
TIG Welding (Gas Tungsten Arc Welding – GTAW): This is a welding process that employs a non-consumable electrode which is the tungsten electrode and shielding gas. Creates very clean and accurate welds, commonly used for thin metals such as aluminum, stainless steel or joints that need to be aesthetically pleasing or structurally sound, but is slower than MIG.
Laser Welding: It uses a laser beam to produce deep narrow welds with low heat penetration. It has the advantage of high speed, high precision, and low distortion. More commonly employed for connecting dissimilar materials, multi-material and lightweight, and AHSS parts.
Other Joining Methods: Mechanical fasteners such as rivets, bolts and screws are also used frequently as well as structural adhesives, especially when welding is done together with bonding, especially for dissimilar materials like aluminum to steel or metals to composites.
Surface Finishing
Surface treatments are carried out on the fabricated component to enhance its durability, appearance or to prepare it for further processing such as painting.
E-coating (Electrophoretic Deposition): A process of applying an organic coating by immersing the object in an aqueous bath and passing an electric current through it. Offers very good protection against corrosion and acts as a base coat for the entire vehicle body (Body-in-White).
Powder Coating: Sprays a dry powder that is charged and adheres to the surface of the material and is then baked on to form a hard skin. Typical for the car body, wheels, and brackets.
Plating: Deposits a thin layer of another metal (e.g., zinc, nickel, chromium) onto the substrate electrochemically. For anti-corrosive, anti-wear, or ornamental applications (e.g., bolts, molding).
Anodizing: A process of electrolytic oxidation of the surface of an aluminum material to produce a hard, corrosion-resistant oxide layer that can be colored.
Painting: The last step in the process of applying a decorative layer to the visible body panels, which includes priming, applying base color, and applying clear coat to protect and add shine.
Important Considerations and Tips in Automotive Metal Fabrication
It is important to note that the choice of a particular process is not the only factor that determines successful outcomes in automotive metal fabrication. Several factors are critical:
Design for Manufacturability (DFM): It is important to design the parts in a way that is best suited for the manufacturing process to reduce costs and time. This includes simplifying geometry where possible, setting the correct tolerances, taking into account the formability of the material (for example, minimum bend radii for sheet metal), ensuring that the features are compatible with the tooling and avoiding complex assembly operations. Cooperation between design engineers and fabrication specialists at the initial stages is possible to bring considerable advantages.
Material Selection Revisited: Further to the basic properties, other factors that need to be considered include the cost of the raw material, availability of the material through the supply chain, recyclability of the material, and compatibility with the joining and finishing processes that are to be used. A critical factor is the relationship between the material and the process that is to be used in the development of the product.
Tooling: Stamping, casting, and forging, among other processes, involve substantial costs in custom tools (dies, molds). Tooling design, material, durability and maintenance are some of the factors that determine the quality of the part and the cost of the project. For small and prototype lots, processes with low tooling costs such as laser cutting, press braking, and CNC machining are used.
Quality control: The automotive industry cannot afford to produce substandard products due to the high competition. Fabrication partners should have well-developed QMS (it can be certified according to IATF 16949). This involves dimensional inspection (CMMs, scanners), material testing, weld inspection, surface finish assessment, and process control to guarantee that the parts are within the required standards.
Cost Drivers: It is important to understand the cost factors. These are cost of raw materials, cost of tools which are spread over the number of units, cycle time, cost of labor, energy cost, rate of scrap, cost of quality control and cost of finishing. This is because the cost of the final part is highly sensitive to the optimization of the design and the process.
Prototyping: This is a process of coming up with models that will help in the validation of the design, fitment and performance before the actual manufacturing of the product using costly tools. Some of the most used rapid prototyping methods are CNC machining, 3D printing for form/fit checks or fixtures, and low-cost and soft tooling for stamping or forming in the automotive development cycle.
Applications of Metal Fabrication in Automotive
Metal fabricated components are used almost everywhere in a vehicle. Key application areas include:
Body-in-White (BIW): The vehicle’s structural framework that is mainly composed of stamped and welded steel and aluminum sheets. It consists of A/B/C pillars, roof, floor, side members, fenders, hood, and trunk lid.
Chassis and Suspension: Frames (for body-on-frame vehicles such as trucks), subframes, control arms, suspension links, knuckles, axles, cross members.
Powertrain: Engine blocks and cylinder heads, crankshafts and connecting rods, transmission cases, exhaust systems, fuel tanks.
Interior: Seat frames and structures, dashboard support beams, pedal assemblies, steering column components.
Safety Systems: Bumper beams, door impact beams, airbag canisters, seatbelt mechanism components.
Thermal Management: Radiators, condensers, heater cores.
Electric Vehicles (EVs): Battery enclosures, motor housings, power electronics casings, charging port structures.
Partnering with TZR for Your Fabrication Needs
Finding a reliable car metal fabrication partner is very crucial in the field of automobile manufacturing. TZR, your dependable partner with more than 20 years of experience, focuses on precision sheet metal fabrication to meet the automotive industry’s rigorous standards. We have comprehensive capabilities, from laser and tube cutting to welding and finishing, enabling us to offer services ranging from prototyping to mass production.
We expertly process steel, stainless steel, aluminum, and other materials, assuring you the best suited material for your needs. With stringent quality control and an industry-high 98% yield rate, we surpass ISO standards. Our experts provide professional DFM analysis so that processes are completed without hitches.
Reach out to us today and let us prove that TZR is the dedicated metal manufacturing partner your automotive project needs for competent services and tailored strategies.
Future Trends Shaping Auto Metal Fabrication
The automotive industry is undergoing rapid transformation, driving innovation in metal fabrication:
Lightweighting: As fuel economy and the range of electric vehicles (EVs) obtain the materials of AHSS, aluminum, and magnesium), as well advanced fabrication techniques for joining and forming the materials while preserving integrity, have become more ces silverlight. Some of the practices that support this trend include tailored blanks (sheets that are welded from different thicknesses/grades before stamping) and hydroforming.
Electrification: EVs present new challenges and opportunities. Large and complex battery enclosures have issues of fabrication, sealing, and thermal management due to the size and complexity of the battery. Electrical auto parts and power electronic enclosures also require special fabrication processes such as aluminum casting, extrusion, and machining.
Additive Manufacturing (Metal 3D Printing): While still limited for mass production due to speed and cost, AM is gaining traction for rapid prototyping, complex low-volume components, customized tooling, and lightweight topology-optimized designs that are difficult or impossible to fabricate conventionally.
Advanced Joining Technologies: Joining dissimilar materials (e.g., steel to aluminum, metal to composites) reliably and efficiently is critical. Techniques like friction stir welding, laser welding, self-piercing rivets, and advanced structural adhesives are becoming more prevalent.
Automation and Robotics: Increased automation in welding, material handling, inspection, and assembly enhances consistency, speed, and safety in high-volume fabrication environments.
Digitalization (Industry 4.0): Integrating digital technologies like IoT sensors for process monitoring, simulation software for optimizing designs and processes, and data analytics for quality control and predictive maintenance is improving efficiency and visibility throughout the fabrication workflow.
Sustainability: Growing emphasis on reducing environmental impact through energy-efficient processes, increased use of recycled materials, minimizing scrap, and developing more sustainable coating and finishing technologies.
Automotive metal fabrication is a dynamic field, continuously evolving to meet the technological advancements and market demands of the global automotive industry. From foundational stamping and welding to advanced laser processes and the integration of digital tools, its mastery remains central to producing the vehicles of today and tomorrow.
