Metal Stamping, also known as punching or pressing, is a manufacturing process in which a flat sheet of metal (coil or blank) is made into a specific shape by passing it through a die in a press. The process includes a variety of metal forming techniques such as blanking, punching, bending, coining, embossing, and flanging.

The core advantages of metal stamping are:

• High productivity
• Low cost
• High precision
• Strong part consistency
• Automated mass production

Main types of stamping processes

Continuous Die Stamping

• Feed the metal strip from the coil into the stamping machine, multi-station gradually complete the punching, shearing, bending, and other operations, and finally obtain the finished product.
• Advantages: high output, good repeatability, low labor cost, less scrap, suitable for mass production of complex geometric parts.

Four-slide stamping

• Use four (or more) synchronized slides acting laterally from different directions to achieve complex cutting and bending.
• Advantages: Flexible design, suitable for fine structural parts; low tooling costs, low scrap; high degree of automation.

Deep Drawing Stamping

• A metal sheet is pressed into the mold cavity by stretching to form a groove structure with a depth greater than the diameter.
• Used for automotive parts, aerospace components, kitchenware, electrical parts, etc.

Short run stamping

• Use customized small batch dies, suitable for trial parts or short-term production, with low die cost but high unit cost.

Composite Stamping

• Compound Die Stamping: A single press is used to complete several processes, such as cutting and punching.
• Transfer Die Stamping: The blank is cut first, and then the device will move the blank to multiple stations for processing, suitable for parts that need to be deep drawn.

Principles and characteristics of deep drawing stamping

What is deep drawing?

Deep drawing is a type of metal stamping that involves pressing a sheet of metal into a die cavity through a die and crimping ring, thereby forming a hollow part with a depth greater than its diameter.

Principal description:

• Positioning of the workpiece: The sheet metal is placed on the die.
• Punch down: The punch moves downward and presses the sheet metal into the mold cavity.
• Material flow: The sheet metal flows radially into the mold cavity, forming a cup or other cavity structure.
• Control of rebound and wrinkling: crimping ring prevents material wrinkling; stroke speed and lubrication control deformation uniformity.

Suitable products:

• Kitchen utensils (pots and pans)
• Automotive oil sumps, filter housings
• Aircraft aluminum fuel tanks
• Medical equipment housings

Detailed Process of Mold Manufacturing

Efficient mold design and manufacturing is the key to ensure the quality of stamping.

The process is as follows:

Product Analysis

• Analyze the part structure, shape tolerance, and material properties.
• Judge whether it is suitable for stamping and the type of stamping (deep drawing, composite, continuous, four-slide, etc.).

Mold Design

• Use CAD software for 3D modeling.
• Design the structure of blanking die, deep drawing die, composite die, guiding device, crimping ring, etc.

Mold material selection

• Commonly used materials: Cr12MoV, SKD11, DC53 and so on.
• Choose according to wear resistance, toughness, processing difficulty.

Mold processing

• CNC roughing and finishing;
• Wire-cutting cutting complex contours;
• Heat treatment (quenching, tempering) to improve hardness;
• Precision grinding to control dimensional accuracy and surface roughness.

Mold assembly and debugging

• Mold component assembly and leveling;
• Small batch mold trial, in-die lubrication, and inspection of stamped parts;
• Tooling optimization and putting into formal mass production.

Common defects and prevention and control measures

The following problems may occur during metal stamping:

Metal stamping application industry analysis

Automotive industry

• The largest amount of use, accounting for more than 40% of the total amount of metal stamping;
• Applications include: inner door panels, oil sumps, brackets, and body skeleton parts;
• Requirements for high-strength, lightweight, commonly used high-strength steel and aluminum alloy.

Electronics and electrical appliances

• Precision stamping: for connectors, contacts, shields, micro-springs;
• Demand characteristics: high precision, small size, large batch.

Medical Equipment

• Stamping housings, conductive parts, fasteners, etc.
• Commonly used materials: stainless steel, titanium alloy;
• Need to meet the medical grade certification and dust-free process standards.

Aerospace

• Deep drawing processing of high temperature alloys, titanium alloys, and other materials;
• Applications: fuel system shells, instrument panel brackets, etc.
• Lightweight, high strength, corrosion resistance, and dimensional consistency are required.

Renewable energy

• Stamped parts are used in wind power generation equipment, battery shells, solar brackets, etc.
• Materials require good electrical conductivity and weather resistance

Stamping design and tooling

Mold Design and Manufacturing

• Tooling design using CAD/CAM technology ensures accurate strokes and clearances. Design models often contain hundreds of process components.
• Tooling processing includes: CNC milling, wire EDM, hardening, grinding, etc.

Stamping Design Guidelines

• Piercing: The diameter of the hole should be ≥ 1.2 times the thickness of the material, ≥ 2 times for hardened steel.
• Edge distance and spacing: For long holes with a length not greater than 10 times the thickness, the edge should be ≥ 2 x thickness from the edge of the material; ≥ 4 x for longer lengths.
• Bending (Bending): the radius of the corner shall be ≥1/2 thickness; the width between the cut, tab, and bend shall be maintained ≥1.5 x thickness.

Material Selection Guide

Selection of stamping materials requires consideration of: toughness, hardness, bendability, machinability, and cost.

The commonly selected materials are as follows:

• Copper alloys: Used for electrical and heat transfer parts, such as copper, bronze, and brass.
• Aluminum alloy: lightweight, corrosion-resistant, used in automotive, aerospace, household equipment.
• Steel, stainless steel: high strength, wear-resistant, used in a wide range of applications, including structural components and medical devices.
• Specialty alloys: such as nickel-based alloys, niobium, precious metals, etc., used in high environments or for microstamped parts.

Cost and Quality Control

Cost Advantages

• Low unit cost for high-volume stampings with good scrap control; durable tooling saves on maintenance and replacement frequency.
• The four-slide process allows for quick design adjustments and savings in tooling costs.

Quality Control

• Use of heat treatment, grinding, cleaning, deburring, plating, wire-cutting finishing, etc. to improve part accuracy and surface quality.

Examples of industrial applications

• Medical device springs and shields: produced using stainless steel + selective tinning + material stacking technology.
• Electrical connector cover: 80% cost savings and lead time reduced from 10 weeks to 4 weeks by switching to single die stamping compared to the original welding solution.
• Automotive airbag metal ring: 34 x 18 x 8 mm deep-drawn part, 24-station continuous mold + DDQ steel + zinc plating.

Metal stamping is a highly efficient, low-cost and consistent quality manufacturing process suitable for the high-volume manufacture of complex metal parts. Excellent quality and economic benefits can be achieved by choosing the right stamping technology, optimizing the design, carefully selecting materials, and matching with precision tooling and secondary processing. Whether for consumer products, automotive parts, aviation equipment or medical devices, metal stamping has a wide range of applications.