1.What are the two definitions of lifespan?
Sharpening life (grinding interval): The number of stamping cycles a die can withstand from its initial sharpening until the cutting edge wears down to the point where the blank exceeds tolerances (typically, burr height exceeds 10-15% of the material thickness) and requires re-sharpening.
Total life (cumulative stampings): The total number of parts produced from a single die from its initial use until it is scrapped due to dimensional deviations, cracking, or fatigue failure after multiple sharpenings.
2.What is the service life range of punching ordinary low-carbon steel cold-rolled coils?
Material thickness range: 1.0mm ~ 3.0mm
Material type: DC01, DC04, SPCC, Q235
Die material: High-quality Cr12MoV, DC53 (hardness HRC 58-62)
Sharpening life: Approximately 50,000 ~ 150,000 cycles (depending on lubrication and clearance uniformity)
Total life: Approximately 1 million ~ 3 million cycles
Note: Usually, one re-sharpening can restore it to like new until the die cutting edge dimensions are out of tolerance or fatigue cracks appear.
3.What is the service life range of stamping high-strength steel or precision stamping steel?
Thickness Range: 3.0mm ~ 6.0mm (or even thicker)
Material Type: 65Mn, 50Mn, S50C (fine stamping steel), Q460, and other high-strength steels
Die Material: High-toughness powder high-speed steel (such as ASP23, ASP60) or cemented carbide
Characteristics: The wear on dies caused by these materials increases exponentially. Especially spring steels such as 65Mn, which not only have high strength but also a certain degree of toughness, resulting in significant impact on dies.
Sharpening Life: Approximately 20,000 ~ 50,000 cycles (ordinary die steel may require re-sharpening after 10,000-20,000 cycles)
Total Life: Approximately 300,000 ~ 1,000,000 cycles
4.What are the key factors that affect lifespan?
Die Clearance
Critical: If the blanking clearance is too small, wear increases dramatically; if the clearance is too large, the cross-sectional quality is poor, and secondary shearing is easily generated, accelerating chipping.
Ideal State: For cold-rolled coils, it is recommended to use 5%~10% of the material thickness as the single-sided clearance (the specific value depends on the material's hardness).
Lubrication Conditions
Dry grinding (without lubrication) vs. wet grinding (with lubrication) can result in a 3~5 times difference in lifespan. Especially for drawing and thick plate blanking, lubricating oil can dissipate heat and prevent metal buildup.
Die Heat Treatment and Surface Treatment
Ordinary Heat Treatment: HRC 58-60, lifespan is average.
Surface Treatment (e.g., TiN coating, TD coating): For blanking 65Mn or high-strength steel, TD treatment can increase the lifespan by 5~10 times compared to ordinary heat treatment. Dies with TD treatment can potentially exceed 2 million blanking cycles for steel plates thicker than 3mm.
Parallelism and Rigidity of the Equipment
If the press has poor rigidity (large deformation of the C-type body) or the slide and worktable are not parallel, it will cause uneven loading of the mold, resulting in local chipping and a significant reduction in its service life.
5.How to estimate its remaining lifespan or determine if a major overhaul is needed?
Burr Exceeding Tolerance: When the burr height exceeds 0.1mm (or specific product requirements), and quickly increases again after re-grinding, it indicates that the die may have entered a fatigue period.
Frequent Chipping: If small chipping occurs repeatedly recently, it indicates that the die steel substrate may be fatigued, and replacement with a new die is recommended.
Abnormal Noise: Hearing a dull or crisp abnormal noise during stamping usually means that the clearance has increased or cracks have appeared.