Stamping Services Information
Stamping services use punches and dies to create three-dimensional parts and add surface definition, such as lettering, to flat-sheet materials. Several operations may be used to cut, form, bend, draw, or squeeze metallic, and in special cases non-metallic, sheet or strip stock. Dimenions, material properties, and intricacy of the designed part govern the stamping process. Suppliers often outsource stamping operations as each fabricated component has unique manufacturing requirements, creating a substantial overhead to operate and maintain a facility that produces a variety of components.
Deep Drawing Stamping Process
Video Credit: metalpressings / CC BY-SA 4.0
Stamping service suppliers may offer one or several different techniques. Blanking and piercing operations provide an economical means of producing two dimensional shapes. Progressive dies are used to produce complex three dimensional shapes that require multiple staged operations. Common capabilities offered include deep drawing, blanking or piercing, fine blanking, fourslide or multislide stamping, and progressive dies.
|Deep drawing uses a punch to fabricate deeply-recessed parts. The depth of a deep-drawn part exceeds its width, as with a cup made from a flat metal sheet.|
|Blanking or piercing operations produce stamped parts by use of a punch and die. A press is used to advance the punch tool through a sheet into the mating die. Blanking and piercing operations typically require finishing or other secondary operations in order to remove sharp edges, burrs, or other rugged features.|
Video Credit: amphihill / CC BY-SA 4.0
|Fine blanking is a specialized, high-precision blanking technique in which material is sheared smoothly through its entire thickness. Fine blanking can be used to produce finished parts that do not require secondary operations.|
Video Credit: Hartford Metaltech / CC BY-SA 4.0
|Fourslide or multislide stamping incorporates the vertical motion of a punch with horizontal die applications from multiple directions, either simultaneously or successively.|
Video Credit: PSS1449 / CC BY-SA 4.0
|Progressive dies are used in production-efficient processes where multiple stamping or forming operations are performed in successive stages or positions along the fabrication cycle.|
Video Credit: aasher666 / CC BY-SA 4.0
Since stamping is a very specialized process that requires large capital investment, only the largest product companies have their own stamping departments. Stamping service providers provide this capability and capacity to everyone else. Part design, dimensions, and features are adapted to the stamping process and a stamping die is built. Stamping itself is done by powerful presses in one step or in many "progressive" steps. Some dies shape while others cut.
Stamping die. Image Credit: DD Engineering Works
Material Physical Properties
Physical properties of the materials that influence the stamping process include tensile strength, yield strength, and elongation. Exceeding the capacity of the material can cause drift, localized strain, or material fatigue.
Tensile strength is the force per unit area required to fracture the material. When modeling the production of a stamped part the tensile strength depicts the size of the press or the force required to pierce or cut through the material.
Yield strength is the force per unit area that a material can be subject to before plastic deformation occurs. When an object undergoes plastic deformation it undergoes a change in shape.
Elongation is measurement that describes the amount of plastic deformation that occurs before fracture.
Stamping operations are modeled and analyzed using engineering software packages such as finite element analysis software (FEA). Tight corner radius, high tensile strengths, low percentage of elongation, and high yield strengths pose design constraints. The ideal model incorporates materials of construction that satisfy the part design, while performing an operation that cuts and forms the material in a manner that minimalizes non-uniform deformation. When the material can withstand the forming process, this solution offers an economical alternative to machining operations.
In some cases heat treating or annealing of materials and components can increase design flexibility.
Force - elongation curve. Image Credit: FMA Communications, Inc.
Stamping services process ferrous and nonferrous metals, exotic metals and alloys, precious metals, and thermoplastic materials. Most operations use ductile metals that are easily deformed while solely experiencing uniform plastic deformation. In specialized operation plastic materials, ultra-hard alloyed steels, or even titanium can be stamped and formed in order to produce a part or component. The following graph illustrated formability and strength, which are for the most part inversely related.
Formability chart. Image Credit: AutoSpeed
Most stamping services provide engineering or design assistance, short-run production, high-volume production, assembly services and/or specialty packaging. By evaluating the services offered you can locate a supplier that best fits your immediate needs.
Secondary operations can be used to improve operational characteristics or supply finishing details. Common secondary operations include anodizing, black oxide coatings, CNC machining, EDM cutting, electroplating, heat treating or stress relieving, and water or abrasive jet cutting.
Anodizing is a galvanic finishing process well-suited to aluminum and its alloys. Anodized finishes provide hardness for wear applications and offer corrosion-resistant properties. They are available in a wide range of colors.
Black oxide coatings are an anti-corrosion treatment for a variety of steels.
Computer numerically controlled (CNC) machining centers are often used to perform very precise machining operations such as turning, milling, and boring.
Electrical discharge machining (EDM) cuts metal via the discharge from an electrode. There are two main EDM categories: wire and ram. With wire EDM, the electrode is a thin wire typically made of brass or other alloys. With ram EDM, the electrode is a specially-shaped piece of graphite or copper alloy.
Electroplating is a finishing process used with materials such as brass, bronze, and copper. A wide variety of colors and textures can be achieved.
Heat treating and stress relieving is a broad category of metal-treating processes such as annealing, passivation, and hardening. Stress relieving may be necessary to relieve residual stresses from the stamping process.
Water or abrasive jet cutting is most often used for two-dimensional cutting. Three-dimensional machining is possible in specialty applications. Pure water jets are used to cut very soft material such as fabrics or rubber. Metals usually require abrasives in the stream. "Water jet" is a generic term that is sometimes used to cover both processes. Advantages include: little material heating during cutting, low side loads, and the ability to achieve complex shapes and tight inside-radii. Low fixturing costs and fast setup, and programming times make this process suitable for prototyping and short-run production.
Certifications and approvals for stamping services include AS 9100, ISO 9001, ISO 13485: 2003, ISO 14001, ISO 16949:2002, FDA registration, IPC certification, and others. Companies who choose to uphold these standards are reviewed periodically and tested in order to meet the current requirements for any specific certification.
- AS 9100 is an expanded, international version of AS 9000, a standard which defines quality system requirements for suppliers to the aerospace industry.
- ISO 9001 establishes requirements for company quality management systems. Standards range from manufacturing to services such as design, development, production, and installation.
- ISO 13485:2003 specifies quality management system (QMS) requirements for organizations that need to demonstrate their ability to provide medical devices and related services.
- ISO/TS 16949:2002 is an ISO Technical Specification that aligns existing American (QS-9000), German (VDA6.1), French (EAQF) and Italian (AVSQ) automotive quality systems standards for the global automotive industry.
Depending on your industry or application, certification can be an important factor when outsourcing your production department.