1. Wear Resistance
When the blank undergoes plastic deformation within the mold cavity, it both flows and slides along the cavity surface, generating intense friction between the cavity surface and the blank. This friction ultimately leads to wear and tear, causing the mold to fail over time. Therefore, the material's wear resistance is one of the most fundamental and critical performance characteristics of a mold.
Hardness is the primary factor influencing wear resistance. Generally speaking, the higher the hardness of mold components, the less wear they experience—and the better their wear resistance tends to be. Additionally, wear resistance is also closely related to the type, quantity, morphology, size, and distribution of carbides within the material.
2. Resilience
Mold operating conditions are often extremely harsh, with some frequently subjected to significant impact loads, which can lead to brittle fracture. To prevent mold components from suddenly fracturing during operation, molds must possess high strength and toughness.
The toughness of a mold primarily depends on the material's carbon content, grain size, and microstructural state.
3. Fatigue Fracture Performance
During the mold's operation, prolonged exposure to cyclic stresses often leads to fatigue failure. These failures can manifest as low-energy multiple-impact fatigue fracture, tensile fatigue fracture, contact fatigue fracture, and bending fatigue fracture.
The fatigue fracture performance of a mold primarily depends on its strength, toughness, hardness, and the content of inclusions within the material.
4. High-Temperature Performance
When the working temperature of a mold is high, its hardness and strength tend to decrease, leading to early wear or plastic deformation and ultimately failure. Therefore, the mold material should exhibit high temper resistance to ensure that the mold maintains high hardness and strength even at elevated operating temperatures.
5. Resistance to Thermal and Cold Fatigue Performance
Some molds undergo repeated heating and cooling during operation, causing tensile and compressive stresses on the cavity surface. This leads to surface cracking and spalling, increases friction, hinders plastic deformation, and ultimately reduces dimensional accuracy—ultimately resulting in mold failure. Cold-and-hot fatigue is one of the primary failure modes for hot-work molds, so these types of molds must exhibit excellent resistance to thermal fatigue.
6. Corrosion Resistance
Some molds, such as plastic molds, generate highly corrosive gases like HCl and HF when heated during operation—gases that are released as chlorine, fluorine, and other elements present in the plastic decompose. These gases erode the surface of the mold cavity, increasing its surface roughness and accelerating wear-related failure.
