What is stamping service and Why Do We Use Them?

Sheet metal stamping is a cold-forming manufacturing technique used to create both simple and highly complex designs quickly, accurately, and cost-effectively. It is capable of creating high-volume parts while maintaining rigorous tolerance and quality criteria. Here, we’ll highlight the sheet metal stamping process and how it works.

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What Is Sheet Metal Stamping?

Sheet metal stamping is the process of transforming sheets of metal material into a useful component or part. During the process, metal is fed into a press where a stamping tool, referred to as a die, presses through or into the metal with great force to create the desired shape. As a cold-forming technique, sheet metal stamping doesn’t require heat to shape the metal.

What Types of Sheet Metal Can We Stamp?

Premier Products of Racine works with a broad range of materials, from aluminum to carbon steel, copper, high-strength steel and more. We also offer galvanized sheet metal stamping services. Pre-galvanized sheet metal is commonly used for creating moisture-resistant components and has the added benefit of being significantly cheaper than aluminum and stainless steel without sacrificing quality.

While virtually any type of metal can be stamped, the type used in any given application depends on the desired qualities of the part that’s being created. Some of the most commonly used materials in sheet metal stamping include:

• Stainless steel
• Aluminum
• Brass
• Copper
• Low- and high-carbon steel
• Coated Steels
• Pre-Painted Steels
• Nickel alloys
• Titanium

The Sheet Metal Stamping Process

There are three components to sheet metal stamping: the sheet metal, the press machine, and the die. However, producing any single component can require many steps before it arrives at its final form. The following are some common processes that might occur during the metal stamping process:

• Forming. This is the process of creating a new shape from flat metal by the application of force. There are several methods to accomplish this, depending on design specifications. By undergoing a series of operations, metal is altered from a simple shape into a highly complex one.
• Blanking. Blanking is the most basic metal stamping process. It involves feeding a sheet into a press where a die then cuts out the desired shape. The piece that results is called a blank. The blank can require additional forming, or it may be the finished component, referred to as a fully finished blank.
• Drawing. A more complex operation, drawing is used to form deep depressions or vessels. During the process, tension carefully draws material into a cavity to change its shape. Stretching of the material is avoided as much as possible to ensure the material stays intact.
• Piercing. This process is often thought of as the opposite of blanking. Rather than keeping the blanks, technicians use the material around the outside of the punched area. During the piercing process, punched-out shapes are discarded, with the hole-riddled sheet metal being the desired product.

Sheet Metal Stamping From Premier Products of Racine

The Basics of Metal Stamping

Metal stamping is a manufacturing process used to convert flat metal sheets into specific shapes. It is a complex process that can include a number of metal forming techniques — blanking, punching, bending and piercing, to name a few.

There are thousands of companies across the U.S. that offer metal stamping services to deliver components for industries in automotive, aerospace, medical, and other markets. As global markets evolve, there is an escalated need for quickly-produced large quantities of complex parts.

Metal stamping is a fast and cost-effective solution for this large-quantity manufacturing need. Manufacturers who need metal parts stamped for a project generally look for three important qualities:

High quality
& durability

Low Cost

Fast Turnaround Time

The following guide illustrates best practices and formulas commonly employed in the metal stamping design process and includes tips to incorporate cost cutting considerations into parts.

Stamping Basics

Stamping — also called pressing — involves placing flat sheet metal, in either coil or blank form, into a stamping press. In the press, a tool and die surface form the metal into the desired shape. Punching, blanking, bending, coining, embossing, and flanging are all stamping techniques used to shape the metal.

Before the material can be formed, stamping professionals must design the tooling via CAD/CAM engineering technology. These designs must be as precise as possible to ensure each punch and bend maintains proper clearance and, therefore, optimal part quality. A single tool 3D model can contain hundreds of parts, so the design process is often quite complex and time-consuming.

Once the tool’s design is established, a manufacturer can use a variety of machining, grinding, wire EDM and other manufacturing services to complete its production.

Metal stamping is a fast and cost-effective solution for this large-quantity manufacturing need. Manufacturers who need metal parts stamped for a project generally look for three important qualities:

High quality
& durability

Low Cost

Fast Turnaround Time

Types of Metal Stamping

There are three major types of metal stamping techniques: progressive, fourslide and deep draw.

Progressive Die Stamping

Progressive die stamping features a number of stations, each with a unique function.

First, strip metal is feds through a progressive stamping press. The strip unrolls steadily from a coil and into the die press, where each station in the tool then performs a different cut, punch, or bend. The actions of each successive station add onto the work of the previous stations, resulting in a completed part.

A manufacturer might have to repeatedly change the tool on a single press or occupy a number of presses, each performing one action required for a completed part. Even using multiple presses, secondary machining services were often required to truly complete a part. For that reason, progressive die stamping is the ideal solution for metal parts with complex geometry to meet:

• Faster turnaround
• Lower labor cost
• Shorter run length
• Higher repeatability

Fourslide Stamping

Fourslide, or multi-slide, involves horizontal alignment and four different slides; in other words, four tools are used simultaneously to shape the workpiece. This process allows for intricate cuts and complex bends to develop even the most complex parts.

Fourslide metal stamping can offer several advantages over traditional press stamping that make it an ideal choice for many applications. Some of these advantages include:

• Versatility for more complex parts
• More flexibility for design changes

As its name implies, a fourslide has four slides — meaning that up to four different tools, one per slide, can be used to achieve multiple bends simultaneously. As material feeds into a fourslide, it is bent in quick succession by each shaft that is equipped with a tool.

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Want more information on 4 axis machining? Feel free to contact us.

Deep Draw Stamping

Deep drawing involves pulling a sheet metal blank into the die via a punch, forming it into a shape. The method is referred to as “deep drawing” when the depth of the drawn part exceeds its diameter. This type of forming is ideal for creating components that need several series of diameters and is a cost-effective alternative to turning processes, which typically require using up more raw materials. Common applications and products made from deep drawing include:

• Automotive components
• Aircraft parts
• Electronic relays
• Utensils and cookware

Short Run Stamping

Short run metal stamping requires minimal upfront tooling expenses and can be an ideal solution for prototypes or small projects. After the blank is created, manufacturers use a combination of custom tooling components and die inserts to bend, punch or drill the part. The custom forming operations and smaller run size can result in a higher per-piece charge, but the absence of tooling costs can make short run more cost-efficient for many projects, especially those requiring fast turnaround.

Manufacturing Tools for Stamping

There are several steps in producing metal stamping. The first step is designing and manufacturing the actual tool used to create the product.

Let’s take a look at how this initial tool is created: Stock Strip Layout & Design: A designer uses is used to design the strip and determine dimensions, tolerances, feed direction, scrap minimization and more.

Tool Steel and Die Set Machining: CNC ensures a higher level of precision and repeatability for even the most complex dies. Equipment like 5-axis CNC mills and wire EDM machines can cut through hardened tool steels with extremely tight tolerances.

Secondary Processing: Heat treating is applied to metal parts to enhance their strength and make them more durable for their application. Grinding is used to finish parts requiring high surface quality and dimension accuracy.

Wire EDM: Wire electrical discharge machining shapes metal materials with an electrically-charged strand of brass wire. Wire EDM can cut the most intricate shapes, including small angles and contours.

Metal Stamping Design Processes

Metal stamping is a complex process that can include a number of metal forming processes —blanking, punching, bending, and piercing and more. Blanking: This process is about cutting the rough outline or shape of the product. This stage is about minimizing and avoiding burrs, which can drive up the cost of your part and extend lead time. The step is where you determine hole diameter, geometry/taper, the spacing between edge-to-hole and insert the first piercing.

Bending: When you are designing the bends into your stamped metal part, it is important to allow for enough material — make sure to design your part and its blank so that there is enough material to perform the bend. Some important factors to remember:

• If a bend is made too close to the hole, it can become deformed.
• Notches and tabs, as well as slots, should be designed with widths that are at least 1.5x the thickness of the material. If made any smaller, they can be difficult to create due to the force exerted on punches, causing them to break.
• Every corner in your blank design should have a radius that is at least half of the material thickness.
• To minimize instances and severity of burrs, avoid sharp corners and complex cutouts when possible. When such factors cannot be avoided, be sure to note burr direction in your design so they can be taken into account during stamping

Coining: This action is when the edges of a stamped metal part are struck to flatten or break the burr; this can create a much smoother edge in the coined area of the part geometry; this can also add additional strength to localized areas of the part and this can be utilized to avoid secondary process like deburring and grinding. Some important factors to remember:

Plasticity and grain direction

Plasticity and grain direction – Plasticity is the measure of permanent deformation a material undergoes when subjected to force. Metals with more plasticity are easier to form. Grain direction is important in high strength materials, such as tempered metals and stainless steel. If a bend goes along the grain of a high strength, it can be prone to cracking.

Bend height

Bend height –The overall height of a bend has minimum requirements to be formed effectively and should be at minimum, 2.5x the thickness of the material + the radius of the bend

Bend relief

Bend relief – Add small notches located immediately adjacent to the portion of the part to be bent — they should be a minimum of twice as wide as the material is thick, and as long as the bend radius plus material thickness.

Bend Distortion/Bulge: The bulging caused by bend distortion can be as large as ½ the material thickness. As material thickness increases and bend radius decreases the distortion/bulge becomes more severe. Carrying Web and “Mismatch” Cut: This is when a very slight cut-in or bump-out on the part is required and is typically about .005” deep. This feature is not necessary when utilizing compound or transfer type tooling but is required when utilizing progressive die tooling.

Want to lower production costs of your stamped metal part?

Download our Metal Stamping Design Guide.
Inside, we cover:

• How to avoid costly design errors
• Cost-effective stamping processes to replace expensive secondary services
• Drawings that illustrate bend relief, plasticity, fracture angle, and more

Download Your Free Design Guide

Additional Resources

Custom Metal Stamping

Custom metal stamping describes metal forming processes that require custom tooling and techniques to produce parts specified by the customer. A wide range of industries and applications employ custom stamping processes to meet high-volume production needs and ensure all parts meet exact specifications.

Custom Metal Stamping Projects

Design engineers can work on a wide range of metal stamping projects for clients across various industries. To better illustrate the versatility of custom stamped metal parts, we’ve outlined a few recent projects completed by ESI’s engineers below.

Custom Stamped Part for Vital Monitoring Equipment in the Medical Industry

A client in the medical industry approached ESI to custom metal stamp a part that would be used as a spring and electronics shield for vital monitoring equipment in the medical field.

• They needed a stainless steel box with spring tab features and were having trouble finding a supplier who would provide a high-quality design at an affordable price within a reasonable timeline.
• To meet the client’s unique request to plate only one end of the part — rather than the entire part — we partnered with an industry-leading tin-plating company that was able to develop an advanced single-edge, selective plating process.

ESI was able to meet the complex design requirements using a material stacking technique that allowed us to cut many part blanks at once, limiting costs and reducing lead times.

Stamped Electrical Connector for a Wiring and Cable Application

In another instance, we were asked to redesign an existing electrical connector cover; the client, AFC Cable Systems, was looking for a higher-quality product at a lower price with shorter lead times.

• The design was highly complex; these covers were meant to be used as daisy chain cables inside in-floor and under-floor electrical raceways; therefore, this application inherently presented strict size limitations.
• The manufacturing process was complicated and expensive, as some of the client’s jobs required a fully completed cover and others did not — meaning AFC had been creating the parts in two pieces and welding them together when needed.
• Working with a sample connector cover and a single tool provided by the client, our team at ESI was able to reverse engineer the part and its tool. From here, we designed a new tool, which we could use in our 150-ton Bliss progressive die stamping press.
• This allowed us to manufacture the part in one piece with interchangeable components, rather than manufacturing two separate pieces as the client had been doing.

This allowed for significant cost savings — 80% off the cost of a 500,000-part order — as well as a lead time of four weeks rather than 10.

Custom Stamping for Automotive Airbags

An automotive client required a high-strength, pressure-resistant metal grommet for use in Ford Transit Vans airbags.

• With a 34 mm x 18 mm x 8 mm draw, the grommet needed to maintain a tolerance of 0.1 mm, and the manufacturing process needed to accommodate the unique material stretching inherent in the final application.
• Because of its unique geometry, the grommet could not be produced using transfer press tooling and its deep draw presented a unique challenge.

The ESI team built a 24-station progressive tool to ensure proper development of the draw and used DDQ steel with zinc plating to ensure optimal strength and corrosion resistance. Metal stamping can be used to create complex parts for a huge range of industries. Curious to learn more about the various custom metal stamping applications we’ve worked on? Visit our Case Studies page, or reach out to the ESI team directly to discuss your unique needs with an expert.

We could not be happier about being a customer of ESI for the past 10 years. They are extremely professional, provide excellent quality, and best of all, make working with them fun.

Len Odegaard
President
Northwest Fastener Sales

I would recommend ESI for future stamped parts (sheet metal parts) in the future. The Gemini shields don’t seem particularly easy to make, and, as you know, we had a difficult time finding a suitable vendor. The quality of work has been great and the dimensional accuracy outstanding. I find them very easy to work with and very accomodating for development. The pricing is fair and it’s nice to work with a local outfit.

Roy Abrams
Senior Mechanical Engineer
Casmed Medical Systems, Inc.