Tool Steel Selection for Progressive Dies
Progressive dies perform multiple operations in sequence, with each press stroke advancing the strip and forming the part step by step. Because production is continuous and often high-speed, the tooling is exposed to repeated impacts, sustained compressive loads, and ongoing friction across multiple stations.
In production, tool life is typically limited by one dominant mechanism. Edges may wear progressively due to abrasion, deform under load, or chip and crack under repeated impact. Material selection depends on identifying which of these behaviors appears first and limits service life.
Core Selection Principle
Tool steel selection for progressive dies depends on how the tooling responds to wear, load, and cyclic impact.
When wear dominates, cutting edges lose sharpness, and dimensional accuracy deteriorates. When compressive strength is insufficient, forming sections deform and lose alignment. When toughness is insufficient, repeated impacts lead to chipping or fatigue cracking, especially at punching and blanking stations.
Material Selection Based on Application Conditions
AISI A2 Tool Steel | 1.2363 | SKD12
A2 is used when wear, deformation, and impact are all present, but none clearly dominate. It provides a balance between wear resistance and toughness, allowing dies to maintain edge condition while resisting cracking under repeated loading.
It is suitable for applications where multiple stations must operate consistently without a single failure mode controlling tool life.
AISI D2 Tool Steel |1.2379 | SKD11)
D2 is used when tool life is limited by abrasive or adhesive wear. Its high carbide content allows cutting edges to retain their geometry over long production runs, which is critical in high-volume stamping.
Once edge chipping or cracking appears during operation, D2 no longer extends tool life and should be replaced by a tougher grade.
AISI O1 Tool Steel | 1.2510 | SKS3
O1 is selected when production volume is limited, and loading conditions are not severe. It provides sufficient wear resistance and toughness for general applications while allowing easier machining during tool fabrication.
Because its dimensional stability is lower than that of air-hardening steels, it is not suitable for high-precision progressive dies requiring tight alignment.
AISI S7 Tool Steel | 1.2355
S7 is used when failure occurs due to chipping, cracking, or fatigue from repeated impact. This is common in heavy-gauge stamping or in stations where punching loads are high.
In these conditions, increasing toughness becomes more effective than increasing hardness. S7 absorbs cyclic impact stresses that would cause fracture in higher-carbide steels.
AISI M2 Tool Steel | 1.3343 | SKH51
M2 is applied in stations where both wear and compressive stress are significant. It is commonly used for punches that must maintain edge strength under repeated loading while resisting abrasion.
Compared with D2, it provides better resistance to deformation. Compared with S7, it maintains higher wear resistance. It is selected when both wear and load contribute to tool failure.
Practical Selection Logic
Selection should be based on observed behavior in production.
When cutting edges wear progressively, and burrs increase in size, D2 is appropriate. When punches deform or lose dimensional accuracy under load, M2 provides better resistance. When edges chip or cracks appear under repeated impact, S7 is required. When these conditions overlap and no single mechanism dominates, A2 provides a balanced solution. In less demanding applications, O1 remains a practical option.
Summary Table
| Tool Steel Grade | Typical Working Hardness | Main Selection Reason |
| A2 | 58–62 HRC | Balanced performance under mixed conditions |
| D2 | 58–60 HRC | Wear resistance for high-volume production |
| O1 | 58–60 HRC | Cost-effective for lower-demand applications |
| S7 | 56–58 HRC | Toughness for impact and chipping resistance |
| M2 | 60–65 HRC | Wear resistance with higher load capacity |
Conclusion
Progressive die material selection depends on identifying whether wear, deformation, or impact-related cracking limits tool life. Once the dominant failure mechanism is clear, the appropriate steel can be selected to address that specific condition.