العربية 
English 
Español 
हिन्दी 
Português do Brasil 
Русский 
日本語 
Deutsch 
한국어 
Français 
Türkçe 
Polski 
Tiếng Việt 
Italiano 
简体中文 Cemented carbide punching die has a wide application range and broad development prospects in die manufacturing industry. This paper mainly introduces the application types, common grades and selection principles of cemented carbide applied in carbide punching dies.
Types of Cemented Carbide Materials for Dies
Cobalt-based cemented carbide is the most widely used material for modern dies, including national standard grades of tungsten-cobalt alloy, tungsten-titanium-cobalt alloy and tungsten-titanium-tantalum (niobium) alloy. In addition to cobalt-based cemented carbide, steel-bonded cemented carbide is also widely applied in die production.
With reliable hardness and wear resistance, steel-bonded cemented carbide retains the machinability and heat treatment performance of steel matrix. It serves as a new type of die material between traditional cemented carbide and tool steel.
Table 1 shows the performance parameters of several common cemented carbide grades and traditional die steels. It can be seen that cemented carbide has higher hardness but lower impact toughness than die steel, and this feature becomes more obvious with the decrease of cobalt content.
Table 1 Performance parameters of cemented carbide and traditional high-grade die steel
Performance Requirements of Cemented Carbide Punching Dies
Basic Process Characteristics and General Material Selection Requirements
Stamping processing applies external force to sheet, strip, pipe and profile workpieces through presses and dies, so as to realize material separation or plastic deformation and produce parts with required shapes and sizes.
Stamping die materials need high hardness, high strength, good fatigue resistance and anti-sticking performance, and cemented carbide can well meet the above working conditions.
Cemented carbide has small deformation and low hysteresis, with the deformation capacity only one eighteenth to one twentieth of die steel, which helps improve the working efficiency of carbide punching dies. However, cemented carbide is sensitive to stress concentration, so it is not suitable for trimming dies due to its application limitations.
Process and Corresponding Material Performance Requirements
Stamping processes are divided into separation process and forming process according to material deformation characteristics. The two processes have different stress states and deformation mechanisms, leading to different performance requirements and selection standards for cemented carbide materials.
Figure 1 Cemented carbide punching die parts
Separation Process
This process includes blanking, piercing and slitting. The die cutting edge applies strong shear force to separate sheet materials along set contours. In working state, the cutting edge bears continuous shear force, friction force and periodic impact force, and the main failure forms include edge wear, chipping and cracking.
Therefore, cemented carbide for separation process requires high hardness, high wear resistance and high compressive strength. Material toughness is selected according to sheet thickness. Thin sheet punching produces small impact load, so low-cobalt and fine-grain cemented carbide is adopted for better wear resistance. Thick sheet punching brings large impact force and radial stress, so high-cobalt and coarse-grain cemented carbide is selected to improve impact toughness and avoid premature die failure.
Forming Process
This process includes bending, deep drawing and flanging. In the forming process, workpieces only produce plastic deformation without material separation, and form target shapes under die pressure. Forming dies bear no severe shear wear, but sustain long-term extrusion stress, bending stress and friction stress, which easily cause material sticking, fatigue deformation and edge collapse.
Cemented carbide for forming process does not require extremely high impact toughness, but needs balanced hardness and fatigue resistance, good anti-sticking performance and stable deformation stiffness. It can resist sheet extrusion and friction, avoid die surface scratch and workpiece sticking, and ensure dimensional stability and surface quality in mass production.
Grade Selection of Cemented Carbide for Thin and Thick Sheet Blanking
Blanking die is the core tool for separation process. Cemented carbide blanking dies have outstanding service performance, with the service life 20 to 50 times that of traditional steel blanking dies, and can complete millions of punching times after each grinding. The punch and die bear strong shear force, friction force and impact load during operation, requiring high compressive strength and impact toughness. Considering the weak toughness of cemented carbide, matching grades should be selected according to sheet thickness.
In industrial production, steel sheets with thickness less than 4 mm are defined as thin sheets, and the rest are thick sheets. Thin sheet blanking is dominated by shear fracture with small axial stress and slight impact force. Low-cobalt and fine-grain cemented carbide such as YG8, YG8X and YG11 are commonly used for higher hardness and wear resistance.
Thick sheet blanking has larger die clearance and obvious sheet tearing, resulting in increased radial stress and impact load on cutting edges. High-cobalt and coarse-grain cemented carbide including YG15, YG15C, YG18C, YG20 and YG25 are applied to prevent die cracking and chipping.
Influence of Contour Complexity on Cemented Carbide Selection
Complex blanking dies and piercing dies are prone to edge chipping under stress concentration. High-cobalt and high-toughness cemented carbide should be selected to avoid premature failure. Standard selection specifications are formed for different punching conditions.
For simple contour piercing dies and box part blanking dies, YG15 and YG11 can be used for punches and dies respectively. For blanking dies with the same material and sheet thickness but complex contours, higher-toughness grades such as YG15 and YG20 are adopted to ensure processing stability and service life.
Table 2 Recommended tungsten-cobalt cemented carbide grades for carbide punching dies under different working conditions
| Die Type | Workpiece Material | Small‑size Die | Medium & Large‑size Die | |||
| Cavity Die | Punch Die | Cavity Die | Punch Die | |||
| Blanking‑piercing Die | Cut‑off Die | Thin sheet | YG8 | YG8 | YG15 | YG15 |
| Piercing & Box‑shaped Part Die | Thin sheet | YG11 | YG15 | ‑ | ‑ | |
| Blanking Die | Thick sheet | YG20 | YG25 | ‑ | ‑ | |
| Complex‑shape Blanking Die | Thin sheet | YG15 | YG20 | YG20 | YG25 | |
| Complex‑shape Blanking Die | Thick sheet | YG20 | YG25 | YG25 | YG30 | |
| Forming Die | Bending Die | ‑ | YG11 | YG11 | YG15 | YG15 |
| Deep‑drawing Die | ‑ | YG8 | YG8 | YG21 | YG21 | |
استنتاج
Cemented carbide has obvious performance advantages over traditional die steel and has become the core material for high-precision and high-life carbide punching dies. Different punching processes and working conditions put forward differentiated requirements on the hardness, toughness and wear resistance of cemented carbide.
Reasonable matching of cobalt content, grain size and alloy grade according to sheet thickness and contour complexity can effectively reduce die failure risks and improve production stability. With the continuous upgrading of punching manufacturing toward high speed and high precision, cemented carbide will maintain irreplaceable application value and further expand its development space in modern die industry.
