The history of metal stamping traces its origins back to the industrial revolution, when it emerged as a revolutionary cold forming technique primarily used to manufacture bicycle frames and handlebars. Rooted in Germany, this method has since evolved into an indispensable cornerstone of contemporary industry, playing a pivotal role in the fabrication of diverse parts and components across an array of sectors.
This article discus various methodologies encompassed by metal stamping, each serving as a unique means of transforming sheet metal into a multitude of forms. Among the fundamental techniques common use are piercing, blanking, flanging, coining, bending, and embossing.
What is Metal Stamping Process?
Metal stamping is a cold-forming procedure that harnesses the potential of specialized dies and stamping presses to reshape sheet metal. These flat pieces of sheet metal are meticulously fed into a sheet metal stamping press. Within this apparatus, a combination of precisely crafted tools and die surfaces come into play, orchestrating the metamorphosis of the metal into entirely new configurations. Operating within production facilities and metal fabrication units, the skilled artisans and technicians steering the stamping operation position the designated material between sections of the die. With calculated force, this interplay of pressure not only moulds the material but also shears it, culminating in the desired definitive shape for the final product or component.
What are the Different Types of Metal Stamping Processes?
Piercing represents a distinctive shearing process within the domain of metal stamping techniques. This method involves the transformation of raw metal as a machining tool penetrates its surface, resulting in the creation of precise apertures—whether circular or of alternative shapes. As the tool initiates its operation, the raw material gives way under the force, leading to the formation of voids.
The material extracted from these holes becomes scrap, a byproduct of the piercing procedure. At the core of this process lies the piercing machine, a robust apparatus that orchestrates the mechanics of transformation. Central to its functioning is the use of a tool known as the blanking punch, chosen for its precision in incising the sheet metal.
In the context of piercing, marked by continuous innovation, various distinct processes come to the forefront, each tailored to create a specific impact on the metal. These processes include:
• Lancing – A process in which a slit is cut partially into the metal sheet, leaving one end attached. The cut-out part can be bent or twisted to create tabs, vents, or louvers.
• Trimming – A process in which the outer perimeter of a formed or flat part is cut away to give the piece part its finished or partially finished profile. The excess material is usually discarded as scrap .
• Notching – A process in which a cutting operation is performed progressively on the outside of a sheet metal strip to create a given strip profile. Notching and trimming are very similar in their function.
• Perforating – A process in which multiple holes are punched into the metal sheet, either for functional or aesthetic purposes. The holes can vary in size, shape, and spacing.
Blanking, a process resembling piercing, differentiates itself with a significant contrast — the punched piece doesn’t end up as scrap; instead, it becomes the finalized product. Frequently, metal stampers employ blanking as an initial step within a broader metal stamping project, followed by other techniques like piercing, bending, or coining.
Blanking serves as a method to craft small or medium-sized metal components by extracting them from larger metal sheets. Known for its simplicity and simultaneous ability to produce precise metal cutouts, this technique is suitable for both low and high-volume production scenarios. In certain cases, the resulting cut metal product might exhibit burrs or undesired sharp edges. Although common, these issues can be resolved through manual deburring, vibratory finishes, or heat deburring methods.
Difference between Piercing and Blanking
As mentioned earlier, both piercing and blanking are metal shearing techniques employed for cutting sheet metal. However, several key distinctions set them apart:
- Material Outcome: In blanking, the portion of material that is cut from the sheet becomes the required part. Conversely, in piercing, the portion punched out from the sheet is considered scrap.
- Dimension Determinants: The dimensions in blanking are determined by the size of the die. On the other hand, the size of the hole created in piercing is determined by the dimensions of the punch.
- Tooling Approach: For blanking, the die is crafted to match the desired part’s size, and cutting clearance is incorporated into the punch. In piercing, this approach is reversed: the punch is produced to the size of the hole, while clearance is introduced within the die.
Flanging constitutes a method for imparting a flare or flange onto a metal workpiece, a transformation achieved through the utilization of dies, presses, or dedicated flanging machinery. This process involves manipulating the metal’s edges to create an outwardly bent region, known as a flange. The flange can vary in shape and size, depending on the specific requirements of the project. Flanging typically involves two opposing dies: a die with a contoured edge and a flat die. The workpiece is positioned between these dies, and when force is applied, the metal yields and bends along the contoured die’s shape, forming the flange.
Flanging serves various purposes across industries. It can enhance the structural integrity of a component by providing additional rigidity along the edges, making it ideal for applications where strength and stability are paramount. Moreover, flanges are often used to enable secure connections between components, allowing them to be easily joined or fastened together. This process exemplifies the precision achievable in metal stamping, where controlled force and carefully designed tooling converge to shape metal into complex and functional configurations.
True to its name, coining stands as a metal stamping technique that mirrors the process of creating coins. In this method, a small piece of metal is subjected to stamping to acquire the precise shape and characteristics of a coin. Coined through a closed die forging process, the metal specimen undergoes stamping either in its entirety or partially. This is accomplished through the convergence of two dies that approach each other from both sides of the metal.
One significant advantage of coining lies in its capacity to produce metal items with stringent tolerances. The technique’s inherent simplicity facilitates the creation of enduring deformations on the product, thereby enhancing its resistance to impact and various forms of physical wear and tear. By harnessing controlled force and meticulously designed tooling, coining exemplifies the precision achievable within the realm of metal stamping, allowing for the production of intricate and durable components.
When incorporating bends into your stamped metal part’s design, ensuring an adequate allowance of material is crucial. It’s essential to design both your part and its blank with sufficient material to facilitate the bending process. Several key considerations should be made in mind:
- Bends positioned too close to holes risk deformation.
- Notches, tabs, and slots should be dimensioned with widths at least 1.5 times the material thickness. Smaller dimensions can strain punches, leading to potential breakage.
- Every corner within your blank design should exhibit a radius equal to or greater than half the material thickness.
- To mitigate burr occurrence and severity, it’s advisable to minimize the usage of sharp corners and intricate cutouts whenever possible. In instances where such features are unavoidable, specifying the burr direction in your design aids in accommodating them during the stamping process.
Embossing stands as a remarkable technique that imparts distinct raised surfaces onto the expanse of a metal sheet. This effect is achieved through one of two approaches—either employing a specialized machine or utilizing a die set designed for embossing.
The versatility of embossing derives from its ability to create intricate designs, making it applicable in a wide array of scenarios. Prime instances include car hoods, door frames, metal coverings, plates, engine housings, and checkered steel plates, among others.
While embossing can be executed on an assortment of materials including steel and various metals, aluminium reigns as the most favoured choice owing to its superior machinability. The lightweight and durable nature of aluminium harmonize seamlessly with the advantages offered by embossing, thereby making it a preferred material for this technique.
From its origins in the industrial revolution, metal stamping has evolved into an indispensable technique that shapes modern industries across the spectrum. Each technique offers distinct advantages and applications that contribute to the versatility and excellence of metal stamping.