Custom Metal Stamping | A Comprehensive Guide

Custom Metal Stamping Overview

Custom metal stamping is, by definition, designed exclusively for a specific part and its functions. Unlike mass-produced stampings, custom metal stamping is chosen when precision and complex dimensions are required to produce a unique part. This process requires the upfront development of a custom metal stamping tool that cuts and forms the part as the metal goes through the stamping press. Custom metal stampings can range from large components for automobiles and custom assemblies to micro-miniature parts for medical devices or electronics.

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Techniques for Shaping Custom Metal Stampings

Stamping includes a variety of sheet metal forming processes consisting of either a single station operation where every stroke of the press produces the desired form of the metal part or could occur through a series of stages. The following techniques are used to achieve the desired shape in the press.

Bending

Bending creates a formed feature by angular displacement of a sheet metal workpiece. In some processes, one edge of the workpiece is clamped in a stationary position while the other edge is clamped by a metal tool and bent over a form to create a precise bend or shape. Alternatively, the metal piece may be pushed into or against a form.

Blanking

The blanking process removes a metal piece from the primary metal strip or sheet when it is punched through the strip/sheet. The material that is removed becomes the new metal workpiece or blank.

Coining

Coining is a forming process that uses an extreme amount of pressure to push the workpiece into a die. The die then forms the metal into a precise shape and creates permanent forms in the workpiece. Coining also smooths the edges of metal parts by striking them with a high degree of force. This removes existing burrs and hardens the metal. Coining may reduce the need for deburring, grinding, and other secondary processes at the end of the project, which saves both time and money.

Crash/Crush Forming

This process deforms the metal using only a punch and cavity. These dies do not control metal flow and cannot prevent the metal from wrinkling or buckling. They are used to form simple parts, such as brackets and braces, made from thick, stiff metals that are more wrinkle-resistant than thinner metals.

Cutting

One of the most common stamping operations, cutting trims the metal into a part by the use of extremely high force in the stamping press. Cutting operations include trimming, notching, piercing, blanking, lancing, and shearing.

Drawing

A complex drawing die is used to create large metal parts, such as automotive components. The process involves controlling the flow of metal into a cavity via a pressure-loaded draw pad to prevent wrinkling as the material flows over a forming punch.

Embossing

Embossing is a cold-forming process used for creating specific formations or designs on metal pieces. Male and female embossing components press a workpiece between them with sufficient force to form the three-dimensional feature.

Extruding

Extrusion forms the metal inside the diameter of a pierced hole, which may be used for applications such as holding fasteners during part assemblies.

Flanging

The flanging operation bends metal along a curved axis, which may be used to form a projection or the rim of a part as it relates to part assembly and stiffness requirements.

Forming

Metal stamping involves a variety of forming operations. The stamping press forms the metal material by applying tension, compression, or both. The specific type of forming operation selected depends on the material’s properties and the part’s critical dimensions, balancing formability and strength.

Ironing

Similar to the coining process, ironing employs compression to form the part by squeezing the metal along a vertical wall to achieve exact thickness and length dimensions.

Lancing

In order to free up metal without separating it from the metal strip, lancing slices or slits the metal, which may be used in progressive dies as a part carrier.

Piercing

This metal cutting operation, also called perforating, produces a hole in a formed part or sheet metal, which may be round, square or a custom shape. The slug is then discarded.

Pinch Trimming

Pinch trimming is a special method in which the vertical walls of a drawn or stretched vessel are cut by pinching the metal.

Punching

This forming process uses a punch press to force a tool, called a punch, through the workpiece/material to create a hole and produces a scrap slug that is deposited into the die below the sheet metal.

Restriking/Sizing

Used primarily after major forming operations are complete, restriking employs an additional station in the die to finish precision details such as small embossing and sharp radii.

Shaving

An operation used to eliminate or minimize die-break, while maximizing the amount of sheared edge.  The general concept with shaving is to pre-punch the hole slightly smaller, then post-punch the hole to size, using a very tight die clearance. This can also be done on a straight or outside edge.

Shearing

Cutting force is applied perpendicular to the material, causing the material to yield and break.

Trimming

The trimming process achieves the specified profile of a stamped part by forming its perimeter or cutting away excess metal, with precision trimming designed to minimize scrap.

Custom Metal Stamping Production Methods

The method chosen for metal stamping production takes into account the complexity of the part and how metal stamping can best form that part. For precision parts with tight tolerances, the method may include the use of in-die sensors to continually monitor part quality, along with other inspection methods. The method also takes into account secondary operations, such as plating, heat treating, welding, and cleaning or sterilization.

Progressive Die Stamping

Progressive metal stamping is a stamping process that advances a metal strip from station to station performing different operations on the same part in the die until the part is complete. Conical-shaped pilots are inserted into pre-pierced holes in the strip to ensure the precision of the alignment as the part advances to guarantee the accuracy of the finished product. Since the part is attached to a metal strip throughout its formation, the entire process and parts will be out of tolerance if the strip is off by even a tiny fraction of an inch.

Progressive die stamping offers some advantages such as being a highly repeatable process and since the material is continuously fed into the stamping press, long production runs can be completed, producing more finished parts in less time resulting in lower cost per part.

Progressive Stamping Delivers High Speed Production and Lower Costs.

Transfer die stamping

Transfer die stamping uses one press to operate multiple tools. The part is removed from its metal strip so that it can be freely transferred.  A part, which can be turned or rotated, is shaped by each station until it is complete. Automation of the transfer process streamlines the operation into a single press.

Transfer dies can handle many part features in one press pass, such as holes, cut-outs or threading, which can eliminate costly secondary operations.

Transfer die stamping is typically used for large parts like frames, tube applications, draws, shells, and structural components.

Is Progressive Die Stamping or Transfer Die Stamping Best for Your Next Precision Metal Stamping Project?

Deep Drawing

Beneficial for applications requiring recessed cavities, where the depth of the drawn part exceeds its diameter, deep drawing uses blanking, swaging or sizing to deform the base material and apply recessed features.

Fine Blanking

Fine blanking is optimal for parts that require very smooth, precise edges or exceptional flatness. Fine blanking is particularly suitable for moving parts such as gears. Fine blanking is a combination of metal stamping and cold-metal extrusion techniques, requiring special presses. 

Progressive Stamping vs. Fine Blanking: Three questions OEMs Should Ask

Multi-slide / Four-slide Stamping

Multi-slide / Four-slide stamping is best suited for fabricating complex components that have numerous bends or twists and for forming wire. The difference between multi-slide and four-slide is that four-slide metal stamping machines have four moving slides while multi-slide machines have more than four slides. The slides or rams in the machines strike the material to produce the finished parts.

Multi-slide / Four-slide equipment can manufacture complicated parts with multiple, complex, or over 90° bends and twists including clips, brackets, flat springs, terminals, retainers, and wire formed parts. Both flat and round materials can be formed.

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Metal Stamping Materials

A key factor in the success of a precision stamped part is specifying the best metal for the process and the application, ranging from lightweight aluminum to heavy-duty steel to high-cost precious metals. OEM engineers can benefit by consulting metal stamping specialists early in the part design phase to evaluate how metal stamping can work and the exact material specifications needed for the application at hand. 

Material selection involves evaluating:

• The properties of the metal
  • tensile strength
  • elasticity
  • conductivity
  • heat capacity
  • corrosion resistance
  • weldability
  • machinability
  • formability
• The thickness and width of the material
•  How well metal stamping can form to specifications with that material
• How the part will perform in the application and operating environment
• The material’s cost and availability

Typical Materials Used For Precision Metal Stampings

Some of the most commonly used materials for precision metal stamped parts include:

Steel

Carbon steel is one of the most popular materials used in metal stamping, which can take on many different forms, properties and finishes, offering optimal strength, performance and cost-effectiveness. Each year, steel production exceeds 1.3 billion tons worldwide. Basic steel is magnetic material. With the addition of chrome and nickel to make stainless steel, it loses its magnetic properties.  Many different types of steel may be used including hot and cold rolled steel; stainless steel; high-tensile steel; low, medium and high carbon steel; and spring steel.

Aluminum

Aluminum offers many advantages for metal stamping applications. Aluminum has the highest strength-to-weight ratio of any metal. Aluminum conducts electricity better than copper and is non-magnetic. For companies seeking sustainability, aluminum is 100% recyclable without losing any of its natural characteristics. However, aluminum can be abrasive in tooling and is more expensive that steel.

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Copper

Copper that is suitable for metal stamping comes in many forms, including such alloys as aluminum clad copper, brass, phosphor bronze, beryllium copper and aluminum alloys. Copper is often selected for stamped components and conductors for electronic devices, as well as electrical wiring, heating and plumbing, and other applications that require its extremely high electrical and thermal conductivity. Copper also resists corrosion while maintaining an attractive appearance. The softness of copper makes it one of the best metals for stamped parts.

Brass

With its reasonable price and flexibility, brass can work for almost any function in metal stamping. As an alloy of copper, brass can easily be soldered to copper. Brass is highly resistant to corrosion and will not rust. It is also effective in carrying electrical current while dealing with high stress very well.  As a result of its unique properties, brass is one of the most-used metal materials in the world.

Titanium

Titanium is known for its corrosion resistance and high-impact toughness. Titanium is very expensive to manufacture but has the highest strength to density ration of any metallic element. It is often used in aerospace structures and implantable medical devices.

Precious Metals

Precious metals may be used as a plating or coating on stamped parts to increase conductivity or to add strength and corrosion resistance to the finished products. In metal stamping, designing a process that conserves the precious metal is critical, due to its high cost and limited availability in some cases. Manufacturers in the automotive, electronics, telecommunications and medical device industries are among the leading users of precious metals such as gold and palladium in critical parts.

Nickel Alloys

Nickel alloys resist high pressure and maintain their properties under extremely high temperatures. They also offer high strength and toughness and excellent resistance to atmospheric corrosion. High nickel alloys are perhaps the most frequently used material for metal stamping production among the hundreds of specialty alloys used in the industry.

Metal Stamping Materials by Industry

Each industry favors particular metals for their precision metal stampings, due to their unique applications and the environmental and operating conditions that the parts must withstand. For example, stamped parts for the automotive industry must be able to hold up under extreme heat and cold, as well as contact with a variety of liquids, while medical devices require high sanitation and safety standards, and electronic parts require electrical conductivity.

Automotive

• Red Metals including Copper, Bronze and Brass
• High-Strength, low-alloy Steel

Medical Device

• Stainless Steel
• Titanium
• MP35N
• Platinum Iridium
• Niobium
• Tantilum
• Aluminum
• Copper
• Custom shaped wire

Electronics

• Mill hard or post heat-treated Beryllium Copper
• Phosphor Bronze and a wide array of high-performance alloys
• Aluminum Clad Copper
• Custom shaped wire

Insert Molding

• Brass and high-performance copper-based alloys
• Pre-plated ferrous and non-ferrous alloys
• Aluminum clad copper
• Custom shaped wire

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Metal Stamping Process

Production of precision metal stampings involves a complex process that begins with design collaboration between the stamper’s and the manufacturer’s engineers. Software simulations are often followed by developing a prototype tool to produce sample parts. Full production planning takes into account every step of the process from custom tool design and stamping through finishing and assembly/packaging to ensure that all critical specifications are met, with quality control from start to finish.

Design Engineering Assistance

Metal stamping engineers can offer solutions for cost-effective part design and production upfront during the estimating process, as they review the part design, prints and material specifications. Using advanced technology, such as 3D CAD, metal stampers can test design options and recommend improvements to reduce failure risk and increase functionality, while meeting all critical specifications and quality standards.

Prototyping

With the development of new custom stampings, it can pay to test and analyze small quantities of stampings before investing in full production. By building a prototyping tool to run sample parts and using simulation software to evaluate how the part and material will function in the tool, the metal stamper can identify and correct potential weaknesses prior to production, which saves on development costs and time to market. The stamper may recommend specialized tool functions, such as progressive dies or in-die assembly, to improve manufacturability.

Production Planning

Collaboration between the manufacturer's technical staff and the metal stamper's engineers in the initial planning stage is key to ensuring efficient production and long-term functionality of the part. In-depth planning sessions allow for review of:

• part specifications
• industrial applications/operating environment
• industry and statutory/regulatory requirements
• industry quality standards (i.e. APQP, DQ/IQ/OQ/PQ)
• unusual risks
• material characteristics
• required secondary operations
• tooling parameters
• control plans
• final assembly/packaging requirements
• demand variances

For manufacturers in the planning process for new products, the technical team of the precision metal stamper can add valuable guidance upfront to help speed time to market.

A designated project manager is responsible for ensuring the project is completed on time and on budget and for communicating status updates to the cross functional team. 

Tool Design, Build and Maintenance

Tool designers review technical specifications and provide critical feedback for tool design. Once designs are approved, highly complex, high-precision tools are built, often including in-die sensors to ensure tool safety and consistent quality. Tooling experts conduct preventative maintenance to ensure tools last the duration of the program with little or no downtime.

Precision Metal Stamping

Sophisticated technology is used for high-speed, precision metal stamping, with a variety of presses that are augmented with advanced features such as electronic servo feeds, robotics, and real-time quality control. Multiple operations like in-die tapping, in-die fastener insertion and in-die assembly can be performed in the stamping press, which can eliminate the need for those secondary operations.

Secondary Operations

Secondary operations are often required to fully finish the metal stamped part for seamless integration into a product or system. Parts may need to be trimmed or welded. Finishing techniques such as coating, plating, polishing or deburring may be chosen to inhibit corrosion, improve appearance, or smooth sharp edges. Metal stampers provide many services in-house, such as cleaning and custom assembly, and also coordinate with approved suppliers for specialized metal finishing services, such as welding or electropolishing.  

Assembly and Packaging

Metal stamping engineers evaluate assembly and packaging needs in the production planning phase to ensure finished parts are ready for further production or shipment when delivered to the manufacturer. Parts may be shipped fully assembled or as sub-assemblies and packaged based on manufacturer specifications (i.e. reel-to-reel, loose piece, on a bandolier).

Quality Control

Precision metal stampers apply mistake-proof processes that incorporate quality controls into every phase of a metal stamping project. Company-wide information sharing systems ensure quality commitments are understood and implemented by every project team member. Sophisticated quality control technology is leveraged throughout the process to ensure zero defects, such as in-die sensors, real-time statistical process control, and optical vision systems.

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Understanding Die Structure: Key Components and Functions

Every precision metal stamping begins with a well-designed die system. A typical stamping die consists of several critical components working together to transform flat sheet metal into complex shapes. Understanding these components is essential for both design optimization and troubleshooting production issues.

The punch and die block form the heart of the stamping system. The punch, the male component, applies force to the material, while the die block (female component) provides the matching cavity. Together, they determine the final shape of the stamped part. Precision machining of these components is crucial, with typical tolerances ranging from ±0.005 mm to ±0.02 mm depending on application requirements.

Guide pins and bushings ensure accurate alignment between the punch and die during each stroke. This alignment is vital for maintaining part consistency and preventing premature tool wear. Most dies use hardened steel guide pins with a minimum hardness of 58 HRC to withstand the repetitive stresses of production.

Stripper plates perform the critical function of removing the stamped material from the punch after each cycle. They must apply sufficient force to clear the material without damaging the part or causing deformation. Spring-loaded strippers are common in progressive dies, allowing for adjustable pressure based on material thickness and type.

Retainer plates secure the punch and die components within the die set, distributing forces evenly during stamping. These plates are typically made from medium-carbon steel (AISI ) and heat-treated to 30-35 HRC for optimal strength and durability.

Stamping Die Types: Applications and Comparative Analysis

Selecting the right die type is fundamental to achieving production efficiency and part quality. Each die design offers unique advantages depending on production volume, part complexity, and material characteristics. Understanding the capabilities of different die types ensures optimal process selection.

Progressive dies stand as the workhorse of high-volume production, capable of performing multiple operations in a single pass. These dies process strip material through a series of stations, each adding a specific feature until the final part is completed. Progressive dies excel in automotive and consumer electronics industries where production runs often exceed 1 million parts annually. Their main advantage lies in eliminating secondary operations, reducing labor costs by up to 40% compared to single-station dies.

Transfer dies offer greater flexibility for complex parts requiring deep drawing or multiple forming steps. Unlike progressive dies, transfer dies process individual blanks that are moved between stations by mechanical transfer systems. This design allows for more complex geometries and larger part sizes, making them ideal for automotive body panels and appliance components. Transfer dies typically require higher initial investment but provide superior dimensional accuracy for parts with tight tolerances.

Compound dies perform multiple cutting operations simultaneously in a single stroke, such as blanking and piercing. This design produces flat parts with exceptional precision, with typical applications including washers, gaskets, and small electrical components. Compound dies minimize part handling and reduce production time by 25-30% compared to sequential operations, though they are generally limited to parts under 150 mm in diameter.

Simple dies represent the most basic die design, performing a single operation per stroke. These dies are cost-effective for low-volume production and prototype development, with tooling costs typically 50-70% lower than progressive dies. Simple dies are commonly used for custom parts and short production runs under 10,000 units, offering quick setup and easy modifications.

Fourslide dies specialize in producing complex, small parts with multiple bends and forms. Utilizing horizontal slides arranged around a central station, these dies can create intricate shapes that would be impossible with conventional dies. Fourslide technology is widely used in the electronics industry for connectors and terminals, where its ability to produce parts with multiple 90°+ bends in a single operation reduces assembly requirements significantly.

Material Selection for Stamping Dies: Critical Performance Indicators

The performance and longevity of stamping dies depend heavily on material selection. The ideal die material must balance hardness, toughness, and wear resistance while remaining cost-effective for the intended application. Three key parameters guide this selection process: hardness, wear resistance, and impact toughness.

Hardness, typically measured on the Rockwell C scale (HRC), directly influences a die’s ability to maintain shape under high pressure. Most stamping dies require a hardness range of 54-62 HRC. Cold work tool steels like AISI D2 (58-62 HRC) offer excellent hardness for blanking and piercing operations. However, higher hardness often comes with reduced toughness, making material selection a critical balance between competing properties.

Wear resistance determines die longevity and maintenance requirements. This property is particularly important for high-volume production and abrasive materials like stainless steel. Carbide inserts provide superior wear resistance, extending die life by 500-% compared to traditional tool steels in certain applications. However, their brittleness limits use to low-impact operations such as fine blanking and shallow drawing.

Impact toughness measures a material’s ability to withstand sudden loads without fracturing. Dies for forming operations, especially those involving high-strength steel, require higher toughness to prevent chipping and cracking. Air-hardening tool steels like AISI S7 (54-58 HRC) offer excellent toughness combined with good wear resistance, making them suitable for complex forming dies. The Charpy impact test provides a quantitative measure of this property, with values above 20 J/cm² recommended for most forming applications.

When selecting die materials, production volume serves as a primary consideration. For short runs (under 100,000 parts), AISI A2 tool steel offers an economical balance of performance and cost. Medium-volume production (100,000-1,000,000 parts) typically benefits from AISI D2 or powder metallurgy steels like ASP-60. High-volume applications exceeding 1,000,000 parts often justify the higher cost of carbide inserts or coated tool steels, which can reduce tool changeovers and maintenance downtime significantly.

The interaction between die material and workpiece material also plays a crucial role. When stamping abrasive materials like high-carbon steel, dies require increased wear resistance. Conversely, forming soft materials like aluminum may prioritize surface finish over wear resistance. Advanced coatings such as TiN (Titanium Nitride) or DLC (Diamond-Like Carbon) can extend die life by 30-50% by reducing friction and wear, particularly in stainless steel stamping applications.

Practical Design Considerations for Die Performance

Effective die design extends beyond component selection to encompass practical considerations that impact production efficiency and part quality. Three critical factors include clearance control, surface finish, and maintenance accessibility. Each element contributes to overall die performance and operational costs.

Clearance control between punch and die directly affects part quality and tool life. Proper clearance ensures clean shearing without excessive burr formation or tool wear. For most carbon steels, optimal clearance ranges from 5-10% of material thickness, with tighter clearances (3-5%) recommended for aluminum and softer alloys. Incorrect clearance can increase punch wear by up to 300% and result in burrs requiring secondary deburring operations. Modern die design software incorporates clearance calculations based on material type and thickness, ensuring optimal performance from the initial design phase.

Surface finish of die components influences both material flow and part quality. Highly polished surfaces (Ra 0.2-0.4 μm) reduce friction during forming operations, minimizing galling and material pickup. This is particularly critical when stamping aluminum or stainless steel, which tend to adhere to tool surfaces. Chemical vapor deposition (CVD) and physical vapor deposition (PVD) coatings not only improve surface hardness but also enhance lubricity, extending die life while maintaining part quality.

Maintenance accessibility often overlooked during initial design, significantly impacts operational costs over the die’s lifespan. Strategic placement of wear components, standardized fasteners, and clear access to critical areas can reduce maintenance downtime by 40-60%. Quick-change inserts for high-wear areas allow for tool maintenance without removing the entire die from the press, a feature especially valuable in high-volume production environments where downtime directly affects profitability.

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