In the field of mold manufacturing, we have over 20 years of experience and understand that the selection of mold materials goes far beyond cost considerations. The performance of materials directly impacts the service life of molds, the quality of finished products, and even overall production efficiency, making it a critical factor in determining mold performance.
If you’re selecting the right mold material for your project, this article will provide you with clear reference points. Based on our project experience, we’ve summarized the key characteristics and typical applications of several commonly used mold materials.
You can start by quickly establishing a basic understanding through the table below, then delve deeper into the selection logic and usage recommendations for each material.
| Material Type | Key Characteristics | Typical Applications |
|---|---|---|
| Pre-hardened Steel (e.g., P20, 718, NAK80) | Medium hardness (HRC 28-40), good machinability, no post-heat treatment needed. | Small to medium-batch injection molds; molds requiring high polish (NAK80). |
| Hardened Steel (e.g., H13, D2, SKD11) | High hardness (HRC 45-52+), excellent wear resistance, high strength, good thermal stability (H13). | High-volume, high-precision, high-wear molds; die-casting molds (H13); stamping and cold forging dies (D2). |
| Stainless Steel (e.g., 420SS, S136) | Excellent corrosion resistance, good polishability. | Medical devices, food packaging molds; molds for corrosive plastics (PVC); high-mirror finish molds (S136). |
| Powder Metallurgy Steel (e.g., ASP23, ASP30) | Ultra-high wear resistance, high toughness, excellent dimensional stability, uniform microstructure. | Ultra-high precision, extra-long life molds; complex stamping dies; high-end injection molds. |
| Aluminum Alloy (e.g., 6061, 7075) | Low density, lightweight, excellent thermal conductivity, fast machining. | Rapid prototyping, small-batch production; blow molds; mold components requiring quick heat dissipation. |
| Copper Alloy (e.g., Beryllium Copper, Chromium Zirconium Copper) | Exceptional thermal conductivity, good wear resistance, high strength (Beryllium Copper). | Mold inserts for local hot spots to improve cooling; high-precision stamping die components (Beryllium Copper). |
| Carbide (e.g., Tungsten Carbide) | Extremely high hardness and wear resistance. | Components of molds subjected to extreme wear (e.g., punches, dies for stamping); ultra-long life parts. |
Tool Steel
In our production, tool steel is undoubtedly the most widely used material. Its outstanding strength, hardness, wear resistance, and thermal stability make it capable of handling various complex scenarios.
Based on specific project requirements, we meticulously select from different tool steel series:
Pre-hardened Steel (e.g., P20, 718, NAK80)
These steels are our top choice for small-to-medium batch injection molds. They are pre-tempered before delivery, typically with hardness ranging from HRC 28 to 40. This allows direct machining without time-consuming secondary heat treatment, which also avoids deformation risks. It significantly simplifies mold manufacturing and shortens production cycles. Notably, NAK80 stands out—when clients demand extremely high surface finishes (e.g., optical lenses or automotive interior parts), its superior polishability effortlessly achieves mirror-like effects.
Hardened Steel (e.g., H13, D2, SKD11):
For molds requiring higher loads, temperatures, or severe wear (e.g., mass production or die-casting molds), we opt for these steels. Unlike pre-hardened steel, they undergo strict quenching and tempering to achieve HRC 45–52 or higher hardness. This extra process delivers superior wear resistance, strength, and extended mold life. H13 is our standard for die-casting molds due to its excellent thermal fatigue resistance. For blanking dies and cold stamping molds, D2 and SKD11 are better choices—their near-ultimate wear resistance ensures stable performance when processing high-hardness materials.
Stainless Steel (e.g., 420SS, S136)
For medical devices, food packaging molds, or plastics that release corrosive gases (e.g., PVC), we typically use these steels. Their excellent corrosion resistance and polishability make them ideal for such applications. S136, in particular, delivers flawless results for transparent plastic parts requiring perfect mirror finishes.
Powder Metallurgy Steel (e.g., ASP23, ASP30)
For ultra-high-precision, ultra-long-life “tough” projects (e.g., precision stamping dies or high-end injection molds), these steels are the ultimate solution. Despite their higher cost, their uniform grain structure provides exceptional wear resistance and toughness, significantly extending mold life—often proving more cost-effective in the long run.
Aluminum Alloy (e.g., 6061, 7075)
Aluminum alloy is another frequently used material in our mold manufacturing. Its thermal conductivity is several times higher than steel, allowing injection molds to cool faster, drastically reducing cycle times and boosting production efficiency.
However, aluminum alloys lack the hardness and wear resistance of steel—for example, 7075 have less than a quarter of the hardness of high-grade tool steels. Thus, they are often used for rapid prototyping and low-volume production molds.
That said, aluminum performs exceptionally well in blow molds, rapid prototyping molds, or components requiring efficient heat dissipation.
Copper Alloy
When localized overheating occurs or enhanced cooling efficiency is needed, we often employ copper alloys (e.g., beryllium copper, chromium zirconium copper). Their excellent thermal conductivity and moderate wear resistance make them ideal for inserts or core materials, precisely placed in mold hotspots. In die-casting molds, copper alloy inserts effectively lower core temperatures, extending mold life while improving production efficiency and product quality.
For high-precision stamping dies requiring elastic components or specific forming sections, beryllium copper is also considered due to its elasticity and fatigue resistance. Given its higher cost, we use it only in critical areas where its unique properties are indispensable.
Carbide
For mold components subjected to extreme wear (e.g., punch dies, concave dies) or demanding ultra-high precision and longevity, we turn to the “heavyweight champion”—carbide (e.g., tungsten steel). With hardness exceeding HRA 90 and outstanding wear resistance, it’s unmatched. However, its brittleness and high price limit its use to scenarios where performance leaves no alternative.
Finally, the selection of mold materials should not rely solely on general experience, but requires comprehensive judgment based on specific project conditions. We recommend consulting with professional mold engineers before making decisions.
Prior to that, it would be helpful to prepare the following key information:
- Basic product characteristics (such as material used, structural complexity, dimensional accuracy, and surface finish requirements);
- Estimated production volume;
- Cost budget range;
- Other special requirements (e.g., corrosion resistance, thermal conductivity, or polishing performance, etc.).
With this information, engineers can more efficiently match you with suitable mold material solutions, achieving the optimal balance between performance, lifespan, and cost.
If you still have questions regarding mold material selection, feel free to contact the RJC mold engineering team, we can provide you with free technical support. Contact now.
