Stamping die structure explained to you in one go
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Table of Contents for Stamping Die Structure Knowledge
I. What is Stamping?
II. Overview of Stamping Processing
III. Technological Characteristics of Stamping Processing
IV. Basic Structure of Dies
V. Basic Components of Dies
VI. Functions of Each Component
VII. Explanation of Commonly Used Stamping Materials
VIII. Appendix:
A. Codes and Hardness of Eight Materials
B. Hardness Values of Commonly Used Steels in Annealed State
I. What is Stamping?
Stamping: A processing method in which pressure is applied to materials such as sheet metal, strip, tube, and profiles using a punch press and dies at room temperature, causing the materials to separate or undergo plastic deformation, thereby obtaining the desired shape and size.
II. Overview of Stamping Processing
Stamping is mainly classified into two categories according to process: a. Separation (Blanking) Process, b. Forming Process
Blanking: The process of separating the product from the material along a certain contour line to obtain the workpiece.
Forming: The process of causing the material to undergo plastic deformation without damage, thereby achieving the desired shape and size of the workpiece.
In actual production, multiple processes are often applied to a set of dies to meet the requirements. For products with complex shapes:
The main stamping processes include: blanking, bending, drawing, and bulging.
Common separation (blanking) process diagrams:
Stamping process: The stamping process, from material deformation to separation, can be divided into three steps:
1. Elastic deformation stage: Under the pressure of the punch, the material undergoes elastic compression, bending, and drawing deformations.
2. Plastic deformation stage: After the elastic deformation stage, the punch continues to press down, causing the stress within the material to reach the yield strength, and the material undergoes plastic shear deformation.
3. Fracture (separation) stage: When the stress near the punch reaches the material's failure stress, the material fractures.
Cut Surface: The cut surface of a stamped product can be divided into four parts:
a. Sloping Angle: This is caused by the mutual compression of the punch and die after the stamping begins.
b. Bright Band: This is caused by the sheet metal near the cutting edge being pulled into the cutting edge and compressed during stamping, resulting in a bright appearance.
c. Tear Band: This is caused by the punch and die compressing and shearing the sheet metal, resulting in a dull appearance and a tendency to rust in air.
d. Burr: This is the shape formed when the sheet metal is about to break in the final stage of stamping.
III. Technological Characteristics of Cold Stamping
Advantages:
1. Stamping can achieve extremely high production efficiency.
2. It can produce products with complex shapes that are difficult to process using other methods. 1. Suitable for products such as thin-shell workpieces.
2. Product dimensional accuracy is related to mold accuracy; therefore, dimensions are relatively stable and interchangeability is high.
3. High material utilization rate, low stamping energy consumption; lower unit product cost.
4. Simple stamping production operation, easy to automate and mechanize.
5. Suitable for mass production.
Disadvantages:
1. Stamping dies are generally complex, with long processing cycles and high costs.
2. High mold processing requirements, difficult to manufacture.
IV. Basic Structural Knowledge of Dies
Classification of Stamping Dies:
① According to the characteristics of the completed process, dies can be divided into: blanking dies (blanking/separation dies); drawing dies; forming dies, etc.
② According to the guiding form of the die, dies can be divided into: guided dies and non-guided dies.
③ According to the process content completed by the die, dies can be divided into: single-operation dies (engineering dies), compound dies, progressive dies.
The first category is generally classified according to the completed content, mostly single-operation dies (engineering dies).
The second category is simply classified according to whether the die has guides. Both single-operation dies (engineering dies) and compound dies exist.
Let's focus on the third category:
Single-operation dies (engineering dies): Dies that complete only one operation in one stamping stroke.
Compound dies: Dies that complete two or more operations in one stamping stroke at the same station.
Progressive dies: Dies with two or more stations where material is fed into each station sequentially with the press (punch press) stroke, thus gradually forming the workpiece.
3. Structure of Engineering Dies
The diagram below shows an engineering die. The components corresponding to the numbers are:
1. Die handle
2. Upper die base
3. Guide bushing
4. Guide post
5. Die cavity
6. Lower die base
7. Fixing screw
8. Stop pin
9. Guide plate
10. Fixed stripper plate
11. Punch... 12. Punch fixing plate
13. Backing plate
4. Component structure of compound mold
The diagram below shows the structure of a compound mold. From top to bottom, the components are:
1. Upper locking plate
2. Upper backing block
3. Upper mold base
4. Upper backing plate
5. Upper clamping plate
6. Female mold plate
7. Inner stripper plate
8. Outer stripper plate
9. Male mold plate
10. Lower clamping plate
11. Lower backing plate
12. Lower mold base
13. Lower backing block
14. Lower locking plate
Compound mold component structure: The diagram below roughly shows the eight plates of a mold:
1. Upper die holder (TP)
2. Upper backing plate (TBP)
3. Punch retainer plate (PP)
4. Stripper backing plate (SBP)
5. Stripper plate (SP)
6. Die core retainer plate (DP)
7. Lower die backing plate (DBP)
8. Lower die holder (DS)
5. Structure of a progressive die The diagram below shows the structure of a progressive die. The components from top to bottom are:
1. Upper locking plate
2. Upper backing block
3. 1. Upper die holder
2. Upper backing plate
3. Upper clamping plate
4. Stop plate
5. Upper stripper plate
6. Lower die plate
7. Lower backing plate
8. Lower die holder
9. Lower backing plate
10. Lower die holder
11. Lower backing block
12. Lower locking plate
Strip material for progressive die production
1. Composition of stamping dies: Classified by the performance of parts, they are mainly divided into: process components and auxiliary components, as shown in the figure below.
V. Basic components of a die
VI. Functions of other parts of a die
2. Structure of the punch
(1) Fixed mounting plate: Lower cost, but inconvenient for maintenance.
(2) Fixed pressure block: Applicable to all dies, convenient for maintenance.
(3) Fixed insert: Generally used for dies with high precision requirements, convenient for maintenance, but higher cost. 3. Stripper Plate Insert: Placed inside the stripper plate, it precisely guides the punch and facilitates mold adjustment. Common types include stepped, locking, and double-layered. The stepped type is the most common.
4. Guide Pins and Misfeed Detection Device: The guide pins precisely guide the material strip before the mold is started. The misfeed detection device connects to a sensor; if the material strip is misfeeded, it prevents the mold from closing, thus protecting the mold.
5. Outer Guide Pillars, Guide Sleeves, and Inner Guide Pillars, Guide Sleeves: These are all mold positioning components (standard parts purchased). During mold operation, the outer guide pillars and guide sleeves perform initial positioning, followed by the inner guide pillars and guide sleeves for precise positioning, ensuring mold accuracy.
6. Limiting Pins: Prevent damage to the mold due to incorrect mold closing height settings, protecting the mold and internal inserts.
7. Guide Pins: Guide pins guide the material during feeding within the mold. They also serve a stripping function. It is recommended to place guide pins as close as possible to the guide pins.
8. Fixing Bolts: The function of fixing bolts is to secure the various components of the mold, providing locking force and maintaining the stability of the mold components under load.
9. Plugs: In molds, plugs are generally used in conjunction with springs to limit the spring's compression under force. Plugs can be used to adjust the spring's preload.
10. Ejector Springs and Ejector Screws: Ejector screws are generally internally threaded, which allows for both fixing the ejector plate and easy removal of the ejector plate. The ejector spring primarily provides sufficient clamping and ejection force to the ejector plate. The clamping force usually refers to the force that holds the material in place. When the mold is working, a blanking force is needed to prevent the material from moving due to force before the mold is finished. The unloading force refers to the force required after the mold is finished, when the punch and material are tightly connected. This is to separate them without affecting the deformation of the material strip. The unloading force is needed to smoothly separate the punch and the material strip.
VII. Explanation of Commonly Used Stamping Materials
●1. SPCC (Cold Rolled Steel Sheet): Cold rolled steel products are made from pickled hot rolled steel sheets, rolled to 0.30-3.20mm at room temperature in a cold rolling mill, and then processed through electrolytic cleaning, annealing, and tempering. Cold-rolled steel products are widely used due to their thinness, precise dimensions, various surface roughness grades, ease of painting and electroplating, good mechanical properties and machinability, and ease of pressing into various products. They are essential materials for a wide range of applications, including automotive bodies, electronic components, home appliances, steel furniture, and containers.
Based on their application, cold-rolled steel products can be divided into the following three categories:
1. General Quality: SPCC, suitable for products with lower processing requirements, such as components for bending, high-precision pressing, and welding.
2. High-Pressure Press Quality: SPCD, with better machinability, suitable for high-precision pressing and forming of components that general quality products cannot handle.
3. **Deep-Ground Quality:** SPCE offers superior processability and is suitable for processing special components that require high formability or time-sensitive applications where SPCE quality is insufficient.
Due to the need for surface electroplating, and environmental concerns, its use is now less common in the computer industry.
2. **SECC (Steel-Clad Sheet):** Electroplated steel sheets use ordinary cold-rolled steel sheets as the base material. After degreasing, pickling, electroplating, and various post-treatment processes on a continuous electroplating line, the product becomes an electroplated product. This product not only possesses the mechanical properties and similar processability of ordinary cold-rolled steel sheets but also boasts superior corrosion resistance and decorative appearance; it is highly competitive and substitutable in the electronics, home appliance, and camera markets.
This product can be categorized into the following three types based on its application:
1. General Quality: SECC, suitable for products with lower processing requirements, such as components for bending, high-precision forming, and welding.
2. High-Pressure Quality: SECD, with better formability, suitable for high-precision forming and forming of components that general quality cannot handle.
3. Deep-Pressure Quality: SECE(N), with even better formability, suitable for processing special components that require high forming or time-sensitive processing, where high-precision forming is not feasible.
3. SPTE (Tinplate): A type of ultra-thin cold-rolled low-carbon steel sheet, primarily used as the base material for tin-plated and chromium-plated iron sheets in the tinplate industry. Highly conductive and aesthetically pleasing, it has been used to replace SUS (Sulfate Metal Sulfate) due to cost considerations. It is a non-magnetic material, but the more stamping cycles it undergoes, the stronger its magnetism becomes. It is commonly used in notebooks as an EMI shielding pan, not for high-strength brackets or plates.
This product can be categorized into three types based on its application:
Single Rolling: T1~T5 materials, T1 is soft → T5 is hard
Second Rolling: DR8~DR10 materials, DR8 is soft > DR10 is hard
Surface Treatment/Symbol Distinguishing Features
B Smooth Finish: A molten, glossy finish is applied to a film with a finely textured, smooth surface.
R Coarse Finish: A molten, glossy finish is applied to a film with a directional whetstone texture.
S-type silver finish: A matte finish achieved by applying a tin layer to a film with a coarse, matte surface, followed by a melt treatment.
M-type dull finish: A matte finish achieved by applying tin to a film with a matte surface, followed by a melt treatment.
4. Phosphor Bronze Sprint (PBS): Phosphor bronze strips are composed of bronze (copper-tin alloy) with added deoxidizers, containing 0.03-0.35% phosphorus (P) and other trace elements such as Fe and Zn. It has excellent ductility and fatigue resistance, making it suitable for electrical and mechanical materials. It also boasts superior contact resistance and material reliability compared to general copper alloys. Formed through continuous melting and casting (sheets, coils), it exhibits high material uniformity. It possesses good conductivity, high elasticity, and excellent wear resistance; it is used as springs and conductive materials in electrical switches and terminals, but it lacks the strength of stainless steel. Electroplating is required. Therefore, it is currently used in notebooks for EMI testing.
C5111: 4% tin content, good strength, good contact resistance, and excellent machinability, suitable for high-performance electrical precision materials.
C5102: 5% tin content, good strength, good contact resistance, and excellent machinability, suitable for high-performance electrical precision materials. C5191: 6% tin content, suitable for motor materials, terminals, IC components, etc., with high strength and hardness.
C5212: 8% tin content, with good strength properties, used in electrical materials.
C5210: 8% tin content, excellent fatigue resistance and elasticity, best suited for high-performance electronic connections.
6. SUS304 (Stainless Steel): The most widely used stainless steel. Because it contains Ni, it is more corrosion-resistant and heat-resistant than Cr steel, and has low-temperature strength, resulting in excellent mechanical properties. It has very high work hardening properties, does not harden after heat treatment, is non-magnetic, has good strength, and is relatively inelastic. Thicknesses typically range from 0.4T to 1.0T. Therefore, it is currently widely used in notebooks for brackets requiring structural strength. A specific grade must be specified to meet design requirements. Generally, 3/4H is preferable. If drawing is required, such as for LCD brackets, 1/2H is generally preferable.
6. SUS301 (Stainless Steel): With a lower chromium (Cr) content than SUS304, its corrosion resistance is poorer, but cold working can achieve very high tensile strength and hardness. Its properties are versatile. Due to its excellent elasticity, it is currently widely used in notebooks for EM protection, serving as elastic contact parts. However, the commonly used thickness is between 0.4T and 0.07T. The grade must be specified to meet design requirements (such as elasticity and strength). It should also be noted that 301 material has a directional metallic crystal structure; the higher the grade, the harder and more brittle it is. If not handled carefully during molding, corner and sidewall cracks are likely to occur.
7. AL1050 (Aluminum Alloy): This material has a relatively high aluminum content, is lightweight, and has good heat dissipation. However, it is difficult to process and has relatively low strength. It possesses excellent formability, weldability, and corrosion resistance. Therefore, it is currently commonly used in notebooks for heat sinks and other areas where heavy loads are not required.
8. AL5052 (Aluminum Alloy): This material has good heat dissipation, is relatively hard, and has high strength. It also has good formability, weldability, and corrosion resistance, but is difficult to process.
Currently, it is widely used in notebook computers as a replacement for tinplate due to its lightweight, excellent heat dissipation, and superior strength compared to ordinary aluminum materials. It can be designed for use in shielding plates, /O brackets, and module drive brackets.
