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Die stamping, a cold forming technique, starts with a strip of metal, often called a blank or tool steel. Using one or more dies, this process shapes and cuts the metal to create a specific design or profile. The force applied alters the blank's structure and geometry, allowing it to be bent or sculpted into complex shapes. This method can produce metal parts of various sizes, from minuscule to enormous, depending on the application requirements.
Also known as pressing, die stamping includes diverse methods such as blanking, punching, piercing, coining, among other operations. Precision in design is crucial to ensure each punch achieves high-quality results.
Dies used in die stamping are specialized tools crafted to create specific designs, ranging from simple, everyday items to detailed components in electronics. They can function as single-use tools or operate as part of a sequence of stages to perform multiple functions.
(These three processes will be further detailed in Chapter 3: Production Methods).
Stamping dies are essential tools in the metal stamping process, serving two primary functions: cutting and forming. Some advanced stamping dies are designed as combination dies, capable of performing both actions in a single stroke. These die stamping operations allow manufacturers to separate sheet metal or shape it into intricate geometries through controlled plastic deformation. Understanding die stamping operations is critical for those seeking reliable, cost-effective solutions in metal fabrication, automotive manufacturing, appliance production, electronics, and many other industrial applications.
Forming dies manipulate and compress sheet metals into precise shapes, functioning much like stencils to create consistent, repeatable results. These forming operations are vital for industries requiring high-volume production and tight tolerances, such as aerospace, medical devices, and automotive manufacturing.
Bending forms basic and complex geometries—such as L, U, or V profiles—by applying controlled force that plastically deforms the workpiece along a single axis, without exceeding the metal's tensile strength. The bending process is a foundation of metalworking and is commonly used in fabricating brackets, enclosures, and automotive components. Automated CNC press brakes and precision dies ensure repeatable bending angles and part accuracy for a wide range of materials, including stainless steel, aluminum, and copper alloys.
Flanging involves bending the edge of a workpiece along a curved axis. The process features two primary types: stretching and shrinking. Tension and compression forces shape the metal, depending on the length of the flange or tab. Flanging operations are ideal for producing curves, corners, or reinforcing features—often found in the automotive, aerospace, and appliance industries. The method's efficiency and accuracy are well-suited for mass production, with modern stamping presses enabling high-volume output while maintaining dimensional integrity.
Drawing is a precision metal forming process that forces the workpiece material to flow radially while retaining nearly the same surface area. The drawn shape adopts the contour of a die, allowing the transformation of flat sheet metal into cylindrical, box-like, or complex hollow components. Drawing preserves material thickness and provides high strength-to-weight ratios, making it indispensable for manufacturing deep-drawn parts such as beverage cans, sinks, and automotive housings.
One advanced drawing method is deep drawing, where the depth of the draw exceeds the diameter of the part, allowing formation of deep, seamless products. Deep drawing is suitable for a broad spectrum of industries due to its ability to produce precision, leak-proof, and cost-effective components.
Stretch forming, or stretching, relies on tension and thinning to increase the surface area of the metal workpiece. This process creates a smooth surface ideal for painting, coatings, and aesthetically driven products. High-pressure dies tightly grip and stretch the metal, resulting in parts resistant to dents and warping. Stretch forming is commonly used for aerospace skins, automobile panels, appliance housings, and architectural components where surface appearance and uniformity are crucial.
Coining uses intense pressure to permanently deform the metal and imprint patterns or features onto the workpiece's surface, reducing its thickness as desired. This high-precision process enables the creation of intricate details, making it ideal for producing currency, medallions, precision gears, electrical contacts, and decorative hardware. Coining delivers sharp edge definition and outstanding repeatability, important for industries demanding close tolerances and high consistency.
Ironing is similar to coining but is specifically utilized to reduce and standardize wall thickness in cylindrical metal parts, such as cans and battery sleeves. By squeezing the part beyond its original thickness—commonly to 30%—ironing ensures uniform, thin walls and increases the vessel's overall length. Manufacturers use ironing in combination with deep drawing for producing lightweight, robust, and seamless containers in high-speed production environments.
Below is a detailed explanation of cutting dies—essential tools for separating metal in die stamping operations. Cutting, also known as shearing, involves applying force until the metal material fails along a specified line, producing high-precision blanks or profiles.
Blanking removes a portion of a sheet metal strip along a chosen contour to create discrete parts, known as blanks. The cut-out blank is the intended workpiece, which is further processed or assembled. The remaining strip material is typically scrap, though it can sometimes be recycled, optimizing material usage and lowering overall production costs. Blanking operations are key in industries such as automotive, appliance, and electronics manufacturing—anywhere repeatable part geometry is required for assembly lines or further operations like forming and welding.
Shearing creates straight, linear cuts in sheet metal and is widely used for producing rectangular, square, or uniquely-shaped blanks. The shearing process accommodates both parallel and angled cuts, ensuring part accuracy and minimal waste. Routine applications range from cutting plate steel for structural projects to producing custom electrical enclosures for cabinets and panels. Advanced shearing equipment allows for high-speed, automated cutting, vital for maintaining high throughput in stamping operations.
Piercing creates holes or specific internal features in a workpiece using a punch and die set. Unlike blanking—where the cut-out becomes the usable part—in piercing, the punched-out section is scrap while the parent material is retained. The precise sizing and placement of holes or cutouts allow for component assembly, fastener installation, or electrical routing in final products. Piercing operations are crucial in the fabrication of panels, mounting brackets, and electronic housings, where customization and tight tolerances are required.
Trimming is the final cutting step in die stamping, used to remove excess flash or material from the perimeter of a formed part. Trimming ensures that each component achieves its specified profile and clean edge, ready for downstream processes like welding, painting, coating, or assembly. This operation is often automated in mass production lines, improving consistency and minimizing manual labor. Industries such as transportation, HVAC, and home appliances rely on trimming for parts with precise dimensional accuracy and high-quality edges.
Notching is a targeted cutting technique performed on the outside or along the edge of the workpiece, preparing it for further bending or forming operations. Creating notches allows easier cornering, simplifies assembly, or facilitates shaping during secondary processes. Notching is common in the production of metal frames, structural supports, cabinet enclosures, and components requiring precise fitment in their final configuration.
The twelve die stamping operations described above represent only a small sample of the techniques available. Custom metal stamping, progressive die stamping, transfer die stamping, and precision engineering allow manufacturers to address a wide range of complex geometries, tight tolerances, and specialized material requirements. Consulting a qualified die stamping manufacturer or metal fabricator enables you to select the optimal die type and process for your specific needs—improving part consistency, reducing overall cost, and accelerating time-to-market. For critical components, in-depth expertise in die design, material selection, and process engineering is invaluable for achieving the highest standards in metalworking and product manufacturing.
Whether you are researching tooling for a new project or evaluating suppliers for mass production of stamped metal parts, understanding these core die stamping operations will help you make informed decisions, ensuring quality, cost efficiency, and scalability in your manufacturing process.
When selecting a die stamping method, considerations such as cost, time, and required geometric tolerances play crucial roles. Below, we describe the three common production types: line, transfer, and progressive.
Line dies are employed for low-volume part production or for very large parts that cannot fit on a single press. The workpiece progresses from station to station, with each station adding a single feature. Combination dies, on the other hand, execute multiple operations in a single stroke during pressing.
Transfer dies operate similarly to line dies, but they synchronize multiple dies together. Parts are evenly spaced on a single press, known as pitch, and are automatically moved between presses on side-by-side rails or manually. Once a cycle completes, the workpiece is gripped and transferred to the next die.
Progressive die stamping has several dies that are activated together. The metal strip, as seen below, is fed through, producing a continuous stream of parts. The stress on the metal is distributed evenly over multiple operations. The equal distance between them is called the progression.
Compound die stamping involves feeding strips of steel through a compound die, which cuts or punches out a part in one stroke. A knock-out mechanism ejects the part, and the steel strip continues through the die. This rapid process can produce parts within seconds, achieving rates exceeding 1000 per hour, thereby reducing labor costs and lead times.
Compound die stamping eliminates the necessity for multiple dies, which can inflate stamping costs. By using a single die, this process ensures consistent accuracy, flatness, and dimensional stability. The preference for compound die stamping stems from its capacity to decrease expenses and minimize waste, addressing critical concerns in contemporary manufacturing practices.
Regardless of the production process, die stamping requires the use of lubricants for:
When punching dies exert force against a metal strip, friction can lead to scratches, burning of the piece, or damage to the die itself. To mitigate these issues, a lubricant is applied to form a protective layer on the metal workpiece. This helps reduce damage to the die and lowers defect rates during the stamping process.
The three methods for applying lubricant are drip, spray, and roller.
Manufacturers use lubricants made from plant, animal, and mineral oils in addition to graphite, soap, and acrylic ones. Modern lubricants are synthetic and do not contain any oil.
There are four main types of die stamping presses: mechanical, hydraulic, servo, and pneumatic, named according to the force-generating mechanism they employ. Each type is categorized into C-frame and straight side varieties, where C-frame presses feature three open sides, while straight side presses have two. The ram or slide, where the upper die is mounted to apply force, can have single or double connectors.
The image below shows a straight side press, equipped with four to eight guideways. These guideways enable it to manage off-centered loads effectively while safeguarding against deflections.
Stamping press manufacturers utilize specific terminology to describe the operation of their equipment, with individual companies often employing proprietary terms. Below is a comprehensive diagram listing all the terms associated with a die stamping press.
Below are selected stamping terms from Sutherland Presses Auto Stamping based in Malibu, CA. For a complete list of their die stamping terminology, please visit their website at https://www.sutherlandpresses.com/news/press-terminology
When communicating with a die casting company, it's advantageous to be familiar with the vocabulary to understand the terminology used.
Hydraulic and pneumatic die stamping presses are widely used, with mechanical presses remaining the cornerstone of the industry. Each type of press employs a distinct method to achieve similar functions with varying types of force. Some models integrate both hydraulic and pneumatic methods. Motor presses represent a recent advancement under evaluation and exploration by major manufacturers.
A pneumatic press utilizes air pressure to drive the downward stroke of the ram, while springs facilitate its upward movement. When activated by the controller, air fills the cylinder, expanding to generate pressure. At the end of the cycle, the air is released, allowing the ram to return to its starting position at the top.
Hydraulic presses provide force using static pressure over a finite and small area. They use pressurized incompressible fluid in a cylinder or cylinders to drive the ram. They are used for metal forming, shallow stretching, and bending. There are three parts to a hydraulic press: machine, power system, and control system.
Until recently, the primary method to increase tonnage was by constructing larger motors. However, press manufacturers have now replaced motors, clutches, and flywheels with servomotors. These servomotors provide precise energy delivery at specific locations, enhancing control over the ram.
Servo presses enable operators to program the dwell time at the bottom of each stroke, ensuring the workpiece settles perfectly before forming. This capability significantly extends the lifespan of the die. Additionally, programming the dwell allows for advanced in-die functions, such as pre-heating the metal before forming. This pre-heating prevents tough materials like stainless steel from tearing during deep draws. Moreover, programmable functions facilitate the use of water-soluble lubricants instead of oil-based lubricants, eliminating the time-consuming and environmentally problematic oil-removal step in subsequent processes. These features make servo forming a compelling alternative to mechanical presses.
All mechanical presses produce force by stored energy from a flywheel. Punches can be 5 mm up to 500 mm at stroke speeds of 20 to 1500 spm. They are categorized by their type of drive, which can be single gear, double gear, double action, linked, or eccentric geared.
Energy stored in the flywheel is discharged using one of the drive types. As the flywheel completes each rotation, it gradually loses energy, reducing its speed by 10 to 15 percent per turn. This lost energy is replenished by an electric motor.
Tonnage � They can vary in size from 20 tons to 1600 tons with the ability to supply substantial force.
| Press Energy Chart | |
|---|---|
| Press Type: Flywheel (Direct drive) | |
| SPM | In.-Tons of Energy |
| 5 | 5 |
| 10 | 19 |
| 15 | 43 |
| 20 | 76 |
| 25 | 119 |
| 30 | 171 |
| 35 | 285 |
| 40 | 285 |
| 45 | 285 |
| 50 | 285 |
There is a wide range of die stamping machines available across the United States and Canada. These machines are indispensable in modern society, playing a pivotal role in manufacturing industries by facilitating the mass production of precise metal components used in diverse products like automotive parts, electronics, and appliances. Below, we explore several popular die stamping machines, highlighting their unique features and characteristics that contribute to their widespread adoption.
Features: Bliss C Series presses are known for their robust construction and high precision.
They provide a broad spectrum of tonnage capacities tailored to diverse die stamping applications. Bliss Presses' C Series presses feature advanced control systems aimed at enhancing productivity and user-friendliness.
Features: The E2 Series of Komatsu Presses has gained acclaim for its energy efficiency and environmentally friendly design. These machines incorporate advanced servo technology, enabling fast and precise stamping operations. The press controls in the E2 Series are user-friendly and provide extensive monitoring and diagnostics capabilities.
Features: The P2H Series of Minster Presses are celebrated for their exceptional precision and productivity. They integrate advanced servo-driven technology to enhance control during the stamping process. Minster Presses are highly regarded for their durability and minimal maintenance needs.
Features: The Seyi M1 Series presses are recognized for their versatility and efficiency in die stamping operations. They offer customizable features tailored to meet specific production requirements.
The M1 Series presses feature intuitive interfaces and enhanced safety measures to optimize the operator experience.
Features: The AIDA NC1 Series presses are renowned for their high-speed capabilities and precision. They incorporate state-of-the-art technology to deliver consistent and reliable stamping performance. The NC1 Series provides a variety of tonnage options to meet diverse metal stamping needs.
Keep in mind that advancements in technology and changes in the market often bring about the introduction of new machines or updates to existing models. For the latest information on the leading die stamping machines available in the United States and Canada, it is advisable to refer to industry publications, visit manufacturers' websites, and consult with industry experts or suppliers in the field.
When selecting a metal for die stamping, several factors should be taken into account, such as its mechanical properties, lubrication requirements, press speed and capacity, magnetic attributes, and the type of steel used in die construction. Die stamping utilizes both ferrous and nonferrous metals, with aluminum being particularly favored for its strength, lightweight nature, and resistance to corrosion.
Two primary considerations must be evaluated when selecting a metal: ductility and tensile strength. Ductility is critical as it determines a metal's ability to be shaped and formed without cracking, tearing, or breaking. Tensile strength, on the other hand, measures a metal's resistance to breaking under tension and pressure. These factors are essential criteria for assessing a metal's suitability for die stamping.
Tensile testing is a straightforward method used to determine how a sample responds under tension, revealing its breaking point when subjected to external forces. These tests provide designers and developers with material analysis reports to predict how a metal will perform in its intended application. The diagram below illustrates the testing process. Tensile strength reports typically include values in megapascals (MPa). For instance, 1090 mild steel has a yield strength of 247 MPa and ultimate tensile strength of 841 MPa, with a density of 7.58. In contrast, aluminum exhibits a yield strength of 241 MPa and ultimate tensile strength of 300 MPa, with a density of 2.7.
Benefits include:
Ductility describes a metal's capacity to deform without fracturing, as depicted in the diagram below.
Four factors contribute to determining a metal's ductility: elongation percentage, tensile strength, yield strength, and hardness.
Elongation percentage measures how much a metal can stretch within a specified distance, typically two inches. For example, a metal with a 38% elongation can stretch 38% of its original length before fracturing when elongated over two inches.
Tensile strength refers to the maximum stress a metal can endure. A higher tensile strength indicates greater ability to withstand stress.
This measure quantifies the force required to shape and deform a metal. When a metal undergoes deformation, it experiences two stages: elastic and plastic. Elastic deformation occurs when it bends under its own weight, whereas plastic deformation involves permanent changes to the metal during processing.
The hardness of a metal is determined using the Rockwell hardness scale, which measures its resistance to penetration by applying weight until the metal surface yields.
Various metals can be utilized in the stamping process, categorized as either ferrous or nonferrous. Ferrous metals contain iron, while nonferrous metals do not. Steel exemplifies a ferrous metal, derived from iron ore, whereas aluminum, devoid of iron, originates from raw aluminum. In general, ferrous metals are magnetic, whereas nonferrous metals are not, with a few exceptions.
Because nonferrous metals lack iron, they are resistant to rust and oxidation. Nonferrous metals commonly used in stamping include aluminum, bronze, brass, gold, silver, tin, and copper. Among these, aluminum is preferred for its strength, lightweight properties, and corrosion resistance.
Of the ferrous metals, steel is the most used in stamping due to its strength and durability.
Because nonferrous metals lack iron, they are resistant to rust and oxidation. Nonferrous metals commonly used in stamping include aluminum, bronze, brass, gold, silver, tin, and copper. Among these, aluminum is preferred for its strength, lightweight properties, and corrosion resistance.
Stainless steel is another type of steel used in stamping, classified as a ferrous metal. The composition of alloys, primarily chromium and nickel, in stainless steel determines its grade. Each grade possesses specific properties and characteristics that make it suitable for diverse applications. For instance, stainless steel grade 316 is ideal for marine applications, whereas grade 304 is preferred for chemical and food processing industries.
Typical grades of stainless steel used for stamping are 301, 302, 304 & 304L, 316 & 316L, 321, 410, and 18-8.
Aluminum, a nonferrous metal utilized in stamping, is valued for its lightweight nature, strength, and resistance to rust and corrosion. Typically, aluminum is alloyed with other metals to enhance its strength and augment specific properties and characteristics.
Aluminum's excellent formability makes it an ideal metal for stamping, as it can be shaped and molded into virtually any configuration.
Copper, similar to aluminum, is a nonferrous metal known for its ease of forming and ability to be shaped into seamless components. It is low maintenance, highly resistant to corrosion, and naturally hygienic, making it suitable for medical, food, and beverage applications. While pure copper is used in stamping, it is often alloyed to improve its durability and strength. Its high ductility makes it well-suited for the stamping process.
Brass is an alloy of copper and zinc, with the proportions of each metal defining its grade and ductility. It features a smooth, silky surface that is easily shaped, resistant to corrosion, and has excellent conductivity. Additionally, brass is chosen for its attractive appearance and superior aesthetic value.
C26000 is among the most widely favored grades of brass, largely owing to its remarkable corrosion resistance. The hardness of brass correlates directly with its zinc content percentage.
Specialty metals encompass a wide range of materials crafted to endure severe environmental conditions without corroding, degrading, or becoming brittle. This category includes diverse titanium and nickel-based alloys. Their extensive variety makes it challenging to generalize their characteristics, as they are specifically engineered to meet precise operational conditions.
Specialty metals commonly share two key attributes: corrosion resistance and heat resistance. Engineering these metals involves enhancing the base material's strength, durability, and resilience against impact and physical damage.
Microstamping involves manufacturing parts that are nearly imperceptible to the naked eye, typically measuring fractions of a millimeter in size. The production of these micro-stamped parts demands highly precise technical procedures with strict tolerances and exceptionally accurate dimensions. These miniature components are created through processes such as line, transfer, or progressive die stamping, where they are pressure-formed at microscopic scales and may include even smaller integrated elements.
Process - Parts are formed in one stroke of the stamping press.
Technical requirements - Dies are specially designed for a single operation.
Lead times � The complex nature of producing dies takes months to produce and configure.
Equipment � Presses and other equipment are the same as in regular die stamping.
Metals � Beryllium copper, phosphor bronze, and brass. The tensile strength of metals has to be precision controlled to ensure quality and proper performance.
The microstamping industry continually encounters new challenges in designing and producing increasingly smaller and more precise parts. Below are some recent advancements in this field.
Rivetless Nutplate � Fastener for use in the aerospace industry.
Micro lumbar retractor � Micro Lumbar Discectomy at 1.57 in (40 mm).
Micro USB Breakout Board � Breakout board with USB Micro-B connector.
One challenge with the die stamping process is its inflexibility. Once a die is cast or a product is produced, there is limited room for reverse engineering or process corrections. However, new auto simulation software enables designers to conduct simulations in a seamless process, minimizing iterations and validating designs before they proceed to manufacturing.
Simulation software is designed to compute the stages of the die stamping process, aiding developers in anticipating potential flaws and errors in designs, including those outlined below.
Tensile failure can occur due to excessive stitching of metal, resulting in deformation like smiling or elongation caused by stretching the metal to its maximum threshold.
a tear or rip caused by too much stretching; happens after necking.
A geometric alteration in a part occurring at the conclusion of the forming process can illustrate the effects of springback, as depicted in the image below.
a result of excessive cold working or strain hardening.
AutoForm and Stamping Simulation technology have the capability to forecast and rectify intricate die stamping issues. The image below illustrates a solution for addressing a springback problem.
Examining the entire process, engineers can simulate each operation, such as drawing, flanging, or coining.
Formed parts � The software provides an image of the completed part for close evaluation and determination of any flaws.
An eyelet is a ring made of metal, rubber, or plastic with flanges, used to reinforce holes punched in thin fabrics. It serves as a smaller alternative to a grommet, which is larger and designed for heavier-duty materials.
A fastener is a mechanical tool, either non-permanent or permanent, that securely connects or affixes two surfaces or objects together. Non-permanent fasteners can be removed without causing damage to the joined materials.
A metal bracket serves as a fastener or connector specifically crafted to securely hold two pieces or objects together. They are utilized for supporting shelves, stabilizing equipment, fastening uprights, or adding decorative accents. Metal brackets are available with various features...
Shim Definition: A shim is a material used to fill gaps or adjust spaces. For example, construction shims are commonly used in window and door jamb installations. Shims can be made from readily available materials, particularly when...
Metal stamping is a cold-working process that converts sheets of metal into predefined shapes using specialized tooling. This process utilizes a punch's stroke to induce a structural change in the metal sheet.
A metal washer is a small, flat piece of metal with a central hole, employed as a spacer, shock absorber, or to distribute the load of a fastener. The hole in the center of a metal washer accommodates a bolt or screw for secure fastening.
The metal stamping process originated during the industrial revolution as a method of cold forming to manufacture bicycle frames and handlebars. Starting in Germany, it has evolved into a critical component of modern industry, used extensively for producing parts and components across various sectors.
A self-drilling screw is a tool designed with features similar to a drill bit or cutting tool. As the name suggests, self-drilling screws can function as fasteners without the need for a pilot hole.
Bolts are mechanical devices utilized for assembling and fastening objects, commonly paired with a corresponding nut. They are intended to be installed into aligned unthreaded holes across multiple parts.
Contract manufacturing is a business model where a company engages a contract manufacturer to produce its products or components. This strategic approach is widely adopted by companies to conserve significant resources and...
Precision sheet metal fabrication is a widely used manufacturing process involving cutting, bending, and assembling metal workpieces through machining. Numerous operations are involved in creating a final sheet metal product...
Sheet metal fabrication involves transforming metals into thin, flat sheets that are subsequently cut and bent into various shapes. Various metals such as brass, steel, copper, tin, titanium, aluminum, and others can be utilized in sheet metal production.
Stainless steel can be shaped using traditional forming and shaping techniques. Austenitic stainless steel, in particular, can be rolled, spun, deep drawn, cold forged, hot forged, or textured under force and stress.
Secondary manufacturing processes, also known as fabrication, refine products from primary processes to produce metal parts or structures ready for end-use. These processes involve reshaping and joining semi-finished metal products.