Die Failure Analysis: Chipping, Galling and Cracking — Root Causes and Prevention

Die failure analysis is not a post-mortem exercise — it is a structured engineering discipline that separates shops running 500,000-stroke tool lives from those replacing dies every 50,000 strokes. In a high-volume stamping line, a cracked punch at 3 AM does not just stop one press; it can cascade into missed deliveries, emergency regrinding, and scrap costs that dwarf the original die price.

This guide addresses the three most common failure modes in metal stamping dies: chipping, galling, and cracking. For each mode, you will find the physics behind the damage, the diagnostic indicators that separate root causes, quantified stress and load calculations, and the prevention hierarchy — from material grade selection to process parameter control. Engineers who apply this framework systematically reduce unplanned downtime by 40–60% within six months.

The analysis methodology follows a structured failure investigation protocol: document the failure, quantify the loads, identify the damage mechanism, isolate the root cause, implement a correction, and verify. Skipping any step produces a repeat failure — a pattern seen routinely in shops where “regrind and run” passes as die maintenance.

What Die Failure Really Costs — Beyond the Tool

Before diving into mechanisms, establish the true cost of a stamping die failure. Most shops track only replacement or regrind cost. This is wrong by a factor of five.

Total die failure cost = direct repair + indirect losses

Direct: regrind ( $200–$ 800 per event), replacement inserts ( $500–$ 5,000), unplanned overtime for repair crew
Indirect: press downtime at full overhead rate ( $150–$ 600/hour), scrap from parts produced just before failure (often 50–200 pieces), customer delivery penalty, quality holds for all parts in the bin at failure time
Hidden: accelerated wear on mating components after a galling event, misalignment stress left in the die set after a cracking event

For a 250-ton blanking press running at 60 strokes/minute producing automotive components, two hours of unplanned downtime costs $12,000–$ 20,000 total. A systematic die failure analysis program that prevents three such events per year pays for itself in the first quarter.

Die Failure Taxonomy: Chipping, Galling and Cracking Defined

Chipping

Chipping is brittle fracture at the cutting edge — the loss of small fragments of tool material from punch or die faces. The fracture originates at stress concentrations (sharp corners, surface defects, grinding burns) and propagates through the brittle carbide or hardened steel matrix.

Visual indicators: Bright, faceted fracture surfaces with angular geometry. No plastic deformation around the chip site. Material missing in discrete fragments, not smeared or displaced.

Scale: Chips range from micro-chipping (sub-millimeter edge crumbling visible only under magnification at 10–20×) to macro-chipping (fragments over 1 mm causing visible part defects and die damage).

Mechanism: Under compressive loading, stress concentrations exceed the local fracture toughness (K_Ic) of the tool material. For D2 tool steel at 60–62 HRC, K_Ic ≈ 18–22 MPa·√m. For cemented carbide (WC-Co, 10% Co), K_Ic ≈ 8–12 MPa·√m. When the stress intensity factor K at the defect tip equals or exceeds K_Ic, the crack propagates catastrophically in a single stroke.

Galling

Galling is adhesive wear between tool surface and workpiece material — the microscopic welding and subsequent tearing that transfers workpiece material onto the die face. In severe cases, built-up edge grows into raised deposits that score subsequent parts, alter clearance geometry, and accelerate die wear.

Visual indicators: Smeared, plastically deformed material on the die face. Surface roughness degrades from Ra 0.1–0.2 μm to Ra 1.5–4.0 μm within hundreds of strokes. Built-up deposits match workpiece chemistry (aluminum, zinc, or iron) rather than tool steel chemistry.

Scale: Galling begins as atomic-scale adhesion at high spots and progresses to macroscopic material transfer within 5,000–50,000 strokes depending on lubrication, surface finish, and material combination.

Mechanism: When the lubricant film breaks down locally, asperity contact under high normal stress (P) and sliding velocity (v) generates frictional heat. The flash temperature at asperity tips can reach 400–800°C in milliseconds, softening both workpiece and tool materials locally. Adhesion bonds form; when the stroke continues, the weaker material (workpiece) tears, leaving fragments on the tool.

Cracking

Cracking in stamping dies encompasses fatigue crack initiation and propagation under cyclic loading, as well as quasi-static overload fractures. Unlike chipping (local edge fracture), cracking threatens the structural integrity of entire die sections — punches, die plates, die blocks.

Visual indicators: Crack propagation paths visible on the fracture surface as beach marks (fatigue) or chevron patterns (overload). Crack initiation sites typically show stress concentration geometry — root radii, cross-bore intersections, grinding marks perpendicular to the loading direction.

Scale: Fatigue cracks grow cycle-by-cycle. At 60 strokes/minute, even a slow-growing crack advances from initiation (0.1 mm) to critical length (3–15 mm in tool steel) in 8,000–200,000 cycles — 2 to 55 hours of production time.

Technical Deep-Dive: Stress Analysis and Failure Thresholds

Blanking Force and Edge Stress

The maximum shear stress at the cutting edge during blanking:

F_blank = L × t × τ_shear

Where:

F_blank = blanking force (N)
L = perimeter of cut (mm)
t = sheet thickness (mm)
τ_shear = ultimate shear strength of workpiece (N/mm²) ≈ 0.6–0.8 × UTS

Example — Blanking 2.0 mm HSLA 340 steel:

L = 400 mm (perimeter of a 120×80 mm blank)
t = 2.0 mm
τ_shear = 0.7 × 440 MPa = 308 N/mm²

F_blank = 400 × 2.0 × 308 = 246,400 N ≈ 246 kN

The edge stress on a punch with cutting perimeter L and edge contact width w (typically 0.1–0.2 mm at failure):

σ_edge = F_blank / (L × w)

σ_edge = 246,400 / (400 × 0.15) = 4,107 N/mm² = 4,107 MPa

Compare to the compressive yield strength of D2 at 62 HRC: 2,200–2,400 MPa. The edge contact stress exceeds yield by 70–85% — which is why cutting edges must operate under compressive stress (pre-stressed through interference fit or compressive residual stress from coatings) to survive.

Hertzian Contact Stress in Galling Onset

At asperity contact, the Hertzian contact pressure P_H:

P_H = (3F_n / (2πa²))

Where:

F_n = normal contact force at asperity (N)
a = contact radius (μm)

For a surface finish Ra = 0.4 μm (typical ground tool steel), asperity tip radius r ≈ 5–20 μm. Under a normal stress of 500 MPa (typical blanking pressure), the Hertzian contact pressure at individual asperities reaches 1,500–3,000 MPa — above the yield strength of zinc coatings (150–200 MPa), aluminum alloy sheet (200–400 MPa), and even mild steel (180–280 MPa). Plastic deformation at the asperity scale is guaranteed. Adhesion follows when the oxide film ruptures.

Stress Intensity Factor for Edge Cracks

For a surface crack of depth a at a punch edge under applied stress σ:

K_I = σ × √(π × a) × F

Where:

K_I = mode I stress intensity factor (MPa·√m)
σ = applied stress (MPa)
a = crack depth (m)
F = geometry correction factor (typically 1.12 for surface crack in a semi-infinite body)

Critical crack depth a_c at chipping threshold:

a_c = (1/π) × (K_Ic / (σ × F))²

For D2 at 62 HRC: K_Ic = 20 MPa·√m, σ_edge = 4,107 MPa (from example above), F = 1.12:

a_c = (1/π) × (20 / (4,107 × 1.12))² = (1/π) × (20 / 4,600)² = (1/π) × (0.00435)² = 1.91 × 10⁻⁵ m ≈ 0.019 mm

This calculation explains why grinding defects of only 20 μm depth at the cutting edge can trigger immediate chipping — the defect already exceeds the critical crack depth under operating stress. Any surface preparation defect larger than this threshold is a die failure waiting to happen.

Fatigue Life Estimation (Modified Goodman)

For a die punch under cyclic compressive-tensile loading (common during snap-through and reverse loading), the modified Goodman criterion:

σ_a / S_e + σ_m / S_ut ≤ 1/n

Where:

σ_a = alternating stress amplitude (MPa)
σ_m = mean stress (MPa), positive = tensile
S_e = endurance limit (MPa) ≈ 0.5 × S_ut for tool steels below 1,400 MPa UTS, drops to 700 MPa for harder grades
S_ut = ultimate tensile strength (MPa)
n = safety factor (typically 1.5–2.0 for dies)

For D2 at 62 HRC: S_ut ≈ 2,100 MPa (compressive) but only 800–1,000 MPa (tensile). S_e ≈ 450–500 MPa. A punch experiencing σ_a = 300 MPa alternating and σ_m = +50 MPa mean tensile (due to snap-through shock) gives:

300/480 + 50/900 = 0.625 + 0.056 = 0.681 → Safety factor n = 1/0.681 ≈ 1.47

Marginal. Add a grinding burn that reduces local S_e by 30%: safety factor drops to 1.02 — right at the fatigue limit. One anomalous stroke with a double sheet trips the fatigue crack.

Step-by-Step Die Failure Investigation Protocol

Step 1: Secure the Failure Scene

Stop the press immediately when failure is detected. Do not regrind or clean the die until documentation is complete. The fracture surface contains the diagnosis; cleaning destroys evidence.

Document within 30 minutes:

Photograph failure location from three angles (macro, close-up, cross-section if possible)
Record: stroke counter at failure, last die tryout date, last regrind date, total strokes since last regrind, material lot currently running, lubricant applied (type, rate, nozzle condition)
Retain 10 parts from just before failure and 10 parts from 1,000 strokes before failure

Step 2: Characterize the Damage Mechanism

Examine the failure surface under 10–50× magnification. Determine:

Chipping: Faceted fracture, no plastic deformation, angular geometry — proceed to Step 3A Galling: Smeared deposits, ductile tearing marks, material buildup — proceed to Step 3B
Cracking: Beach marks or chevrons, propagation path visible, crack origin identifiable — proceed to Step 3C

Perform EDS (Energy Dispersive Spectroscopy) or simple file test on deposits: workpiece material (galling) vs. tool material (fatigue spall).

Step 3A: Chipping Root Cause Tree

Check clearance: measure actual punch-to-die clearance with pin gauges. Compare to specification. Insufficient clearance (< 6% of t for mild steel) concentrates stress at the edge and drives chipping.
Check hardness: Rockwell test at three locations on failed tool. If HRC > 63, tool is overhard → brittleness increase → chipping susceptibility. Regrind protocol may have removed tempered zone.
Check grinding parameters: inspect for thermal damage (blue or brown discoloration, magnetic particle inspection for cracks). Grinding burns introduce tensile residual stress that reduce K_Ic by 40–60%.
Check edge geometry: under 20–50× magnification, verify edge radius. Sharp edge (< 0.01 mm radius) concentrates stress 3–5× more than 0.03 mm radius edge.
Check workpiece: verify material cert. HSLA and AHSS grades processed with wrong clearance are a top chipping driver.

Step 3B: Galling Root Cause Tree

Measure surface roughness (Ra, Rz) on failed tool. Compare to specification (typically Ra 0.1–0.2 μm for polished forming surfaces). Values above Ra 0.4 μm indicate inadequate finishing or previous galling damage.
Identify workpiece material: aluminum alloy, zinc-coated steel, and austenitic stainless all have high galling affinity with standard D2 tooling. Requires either coating (TiN, TiCN, DLC) or chrome-plated surface.
Check lubrication: verify lubricant viscosity vs. application rate vs. contact pressure. Calculate minimum film thickness with Hamrock-Dowson equation or check against supplier data. Film starvation = galling.
Check operating speed: high SPM increases surface temperature. For aluminum: limit contact pressure × velocity (PV value) to < 1.5 MPa·m/s without coating.
Check material hardness mismatch: tool surface hardness should be 10–15 HRC harder than workpiece to resist adhesion.

Step 3C: Cracking Root Cause Tree

Identify crack origin: look for stress concentration geometry at origin (sharp corner, cross-bore, retaining ring groove, grinding mark).
Determine fracture mode: fatigue vs. overload. Fatigue = slow propagation, beach marks, often multiple initiation sites at low-stress areas. Overload = single catastrophic event, chevron/herringbone pattern pointing to origin.
For fatigue cracks: calculate stress amplitude (σ_a) from press load monitoring data. Compare to endurance limit. Check maintenance log for anomalous press loadings (double sheets, misfeeds, overloads).
For overload cracks: check for press overload events, snap-through shock (verify counterbalance pressure), material thickness out of spec.
Examine heat treatment records: verify hardening temperature, quench medium, and tempering cycles. Improper austentizing temperature creates grain boundary carbide networks → embrittlement → cracking at moderate loads.

Step 4: Quantify Root Cause Confidence

Use a ranked table (see comparison section) to assign probability to each potential root cause based on evidence weight. Implement the highest-probability correction first, then re-evaluate at 10,000 and 50,000 strokes.

Step 5: Implement Correction and Verify

Document all changes to the process control record. Run a controlled experiment: change one variable at a time, maintain stroke log, collect parts at 5,000-stroke intervals for first 50,000 strokes after correction.

Root Cause Comparison and Selection Matrix

Evidence Found	Most Likely Root Cause	Secondary Cause	Tertiary Cause
Chipping + clearance undersize by >15%	Wrong clearance	Material grade mismatch	Edge radius too small
Chipping + grinding burn marks	Thermal grinding damage	Over-hardening (HRC >63)	Coolant failure during grind
Galling + Al/Zn deposit + Ra >0.4 μm	Surface finish inadequate	Lubricant starvation	Missing die coating
Galling + good finish + correct lube	Wrong lubricant chemistry	PV value exceeded	Coating worn through
Fatigue crack + beach marks + origin at fillet	Insufficient fillet radius	High cyclic alternating stress	Snap-through shock
Overload crack + chevrons + press alarm	Die protection failure	Double sheet event	Press overload setting wrong
Chipping + hardness in spec + clearance OK	Residual stress from EDM/grinding	Workpiece inclusions hitting edge	Insufficient edge radius
Galling + cracking at same location	Combined wear-fatigue	Galling notch then fatigue crack	Inadequate lubrication system

Five Common Die Failure Mistakes That Multiply Costs

1. Regrinding Without Root Cause Identification

“Regrind and run” is the most expensive non-solution in stamping. Regrinding removes only the damaged material — it does not fix the clearance, the surface finish, the hardness, or the lubrication that caused the failure. Tools regrinding without investigation return to the same failure mode within 20–40% of their previous life. In a shop running three presses, this approach wastes 15–25 regrind events per year that correcting the root cause would have prevented.

2. Grinding Without Thermal Management

Grinding is the most common way to introduce new failure seeds into a repaired die. Wheel specifications, infeed rate (mm/revolution), dressing frequency, and coolant flow rate all affect surface temperature. A grinding infeed rate 50% too aggressive at insufficient coolant generates surface temperatures exceeding 600°C, which converts martensite back to austenite in a thin surface layer. On cooling, this layer contracts, generating tensile residual stress up to 800 MPa — enough to initiate fatigue cracks before the die even reaches the press. Protocol: after regrinding any punch or die insert, perform Barkhausen noise analysis or nital etch inspection to verify absence of thermal damage. Do not skip this step.

3. Incorrect Clearance After Regrind

Each regrind removes material and reduces punch cross-section by 0.005–0.020 mm per side per regrind event. If clearance is not re-measured and shimmed after each regrind, tools progressively run tight over their regrind life. A punch that started life at 12% clearance (per t) may be running at 8% clearance after five regrinds — which is below the chipping threshold for HSLA materials. Shops that do not track punch life per regrind interval and re-measure clearance at each service systematically drive themselves into chipping failures.

4. Using Standard D2 for Galling-Prone Materials

D2 tool steel at 60–62 HRC is the industry default. It performs well for mild steel and most cold-rolled carbon steel applications. For aluminum alloy (3xxx, 5xxx, 6xxx series), zinc-coated steel, and austenitic stainless (304, 316), D2 is an inadequate choice without surface coating. The affinity between aluminum and iron is high; galling onset with D2 on aluminum occurs within 2,000–5,000 strokes at production speeds. TiN-coated D2, TiCN, DLC, or chrome-plated D2 extends that life to 100,000–500,000 strokes. Shops that specify D2 for aluminum blanking are paying for coating performance in regrind and downtime costs.

5. Ignoring Snap-Through and Reverse Tonnage

Cutting dies generate a snap-through event at punch penetration — the moment when the material fractures completely and the punch load drops suddenly from peak blanking force to near zero. This snap-through generates a reverse load (upward impact) on the ram, die shoe, and punch holder. In presses without pneumatic counterbalance or hydraulic overload protection, this reverse load propagates as a shock wave through the die structure. Punch shanks, backing plates, and die retainers loaded in reverse tension are common fatigue crack initiation sites. Reverse tonnage monitoring — available on most modern press controls — should be checked against the tool steel tensile strength limit. If reverse tonnage exceeds 10% of press capacity, angular shear on the punch face, staged penetration, or counterbalance adjustment is required.

Industry-Specific Applications and Production Examples

Automotive Body-in-White: AHSS Blanking

A tier-1 automotive supplier running DP780 dual-phase steel at 1.8 mm thickness experienced punch chipping every 12,000–18,000 strokes on a progressive die with 8% clearance (per t). Failure analysis identified: clearance correctly set for mild steel (8%), but DP780 requires 12–14% clearance due to its higher yield-to-tensile ratio and spring-back force component. Punch material D2 at 62 HRC had been used successfully on the mild steel version of the same part. Root cause: wrong clearance specification carried forward from mild steel tool without AHSS adjustment. Correction: increase clearance to 13%, switch to PM tool steel (Vanadis 4E) for better fracture toughness — life extended from 18,000 to 85,000 strokes between services.

Home Appliance: Aluminum Lid Deep Drawing

A major appliance manufacturer drawing 0.8 mm AA5052-H32 aluminum lids experienced galling on forming radii within 3,000–6,000 strokes. Surface analysis: Fe-Al alloy deposits on punch nose, Ra growing from 0.15 μm to 1.8 μm within 5,000 strokes. Root cause: uncoated D2 punch, insufficient lubricant application (nozzle partially blocked), and production speed 20% above design. Correction: TiN-PVD coating on punch nose and die radius, automated lubricant spray system with flow verification, SPM reduced to design specification. Life extended to 150,000+ strokes without galling intervention.

Electrical Components: Copper Stamping

Progressive die for copper bus bar blanks (C11000, 3.0 mm thickness) experienced die cracking at punch retainer cross-bore location after 250,000 strokes. Fracture surface showed fatigue beach marks radiating from cross-bore inner edge. Root cause: cross-bore machined perpendicular to punch loading axis — maximum stress concentration location. K_t (stress concentration factor) at cross-bore edge = 2.8–3.5. Cyclic stress amplitude from copper blanking × K_t exceeded endurance limit of H13 material at that location. Correction: replace cross-bore retention with circumferential shoulder, apply compressive shot peening to punch shank, switch to D6A tool steel with higher fracture toughness. Life extended beyond 800,000 strokes.

Contract Stamping: Stainless Steel Washers

A high-volume contract stamper producing M8 washers from 304 stainless at 1.5 mm experienced combination galling + chipping failure every 8,000–10,000 strokes. Stainless work-hardening during blanking (n ≈ 0.45) increases punch pressure in the final 20% of penetration by 60–80% over nominal. Uncoated D2 punch experienced adhesive wear from stainless on every stroke, building an abrasive deposit that then concentrated stress at the cutting edge. Correction: DLC-coated punch (H:DLC type, 1,500 HV surface hardness), 15% clearance, sulfurized extreme-pressure lubricant at 4× previous flow rate. Life increased from 10,000 to 120,000 strokes.

FAQ: Die Failure Analysis

Q1: How do I distinguish chipping from galling under shop-floor conditions without laboratory equipment?

Chipping leaves clean, angular, bright fracture surfaces — the material is absent, not moved. Galling leaves smeared deposits that are a different color than the tool steel (often gray-silver for aluminum, white for zinc, dark gray for stainless work hardening). A stiff wire brush will not remove galling deposits without removing tool material with them; they are bonded. Chisel test: galling deposits flake off with a sharp tool; a chip void cannot be filled back.

Q2: What is the minimum edge radius needed to prevent chipping on D2 at 62 HRC?

For blanking mild steel (UTS 280–400 MPa) at 8–12% clearance: 0.02–0.03 mm edge radius (controlled honing). For HSLA (UTS 340–550 MPa) at 12–14% clearance: 0.03–0.05 mm. For AHSS/DP (UTS 600–980 MPa): 0.05–0.08 mm. Edge radius is applied by fine honing (felt wheel + diamond paste or ultrasonic stone) and verified under 50× magnification. Never leave a sharp ground edge on a production die.

Q3: How often should I check clearance during production?

At a minimum: after every regrind, after any double-sheet or overload event, every 100,000 strokes for high-volume runs. In precision stamping (tolerances ±0.05 mm or tighter): every 50,000 strokes. Tools running galling-prone materials should have a dedicated clearance check schedule because galling deposits alter effective clearance.

Q4: Can I repair a galled die surface without full regrind?

Minor galling (deposits < 0.1 mm height, Ra < 0.8 μm) can be addressed with hand polishing using 600–800 grit abrasive paper followed by diamond paste finishing to Ra < 0.2 μm. Severe galling (deposits > 0.2 mm, Ra > 1.5 μm) requires surface grinding to remove the contaminated zone completely, then refinishing. Do not attempt to polish away severe galling — you are embedding abrasive particles into the galling deposit and grinding the tool surface simultaneously, creating a new failure initiation zone.

Q5: What is the maximum number of regrinds before a punch must be replaced?

This depends on the original punch length minus the minimum engaged length required to maintain die alignment. A standard punch ground to 0.1 mm per regrind with a 5 mm life allowance can sustain 50 regrind cycles — in theory. In practice, fatigue damage accumulates with each regrind if the root cause is not eliminated, and heat-treatment integrity degrades in heavily re-ground tools. Most shops replace punches at 30–40% of theoretical life due to accumulated damage concerns. For critical automotive features (safety-classified holes, datum slots): establish a mandatory replacement interval at 50% of calculated theoretical life, regardless of apparent condition.

Q6: Should I apply TiN coating to all dies to prevent galling, or only certain applications?

TiN coating is cost-effective when the uncoated tool life is less than 100,000 strokes for galling-related failure. For mild steel stamping at normal speeds with adequate lubrication, uncoated D2 typically runs 300,000–500,000 strokes without galling — coating adds cost without proportional return. For aluminum alloys: TiN or TiCN coating is standard practice — the cost-per-stroke benefit is clear. For zinc-coated steel: TiCN or DLC is preferred over TiN (TiN has moderate affinity for zinc). For austenitic stainless: DLC or chrome-plated inserts. Always evaluate coating cost against uncoated life extension. The decision formula: coating cost per insert / (strokes per coated life − strokes per uncoated life) = cost per additional stroke.

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Conclusion

Die failure analysis is not complicated — it is systematic. The three primary failure modes (chipping, galling, cracking) each have distinct diagnostic signatures, root cause trees, and corrective actions. The critical discipline is documentation: a failure with no records yields a hypothesis at best; a failure with stroke counter data, material certs, press load history, and regrind records yields a diagnosis.

The quantitative tools in this guide — edge stress calculation, Hertzian contact analysis, fracture mechanics critical crack depth, and Goodman fatigue criterion — are not academic. They are the engineering basis for setting clearance specifications, hardness targets, surface finish requirements, and coating selection. Running these numbers before die design is orders of magnitude cheaper than running them after die failure.

The die failure analysis framework reduces to four non-negotiable practices:

Document failures fully before touching the die
Match clearance to workpiece material grade, not to habit
Inspect for grinding burns after every regrind
Evaluate coating against application-specific life data, not generic recommendations

Shops that implement these four practices systematically move from reactive fire-fighting to planned tool life management — and the financial impact is measurable within a production quarter.

Contact Demirezen Engineering

Demirezen Engineering specializes in stamping die failure analysis, tool life optimization, and press line reliability engineering. If your operation is experiencing recurring die failures that regrinding alone does not resolve, we provide structured failure investigation services — from root cause identification to corrective action implementation and die life verification.

WhatsApp: +90 543 341 6183
Website: demirezenengineering.com

We work with stamping operations in Turkey, Egypt, and the broader MENA and GCC region. Our failure analysis engagements typically recover 30–60% of recurring die failure costs within the first production quarter through corrective action on root causes.

Internal Link Suggestions

External Reference Suggestions

ASM International — Failure Analysis and Prevention, Volume 11, ASM Handbook (asm.org)
Schuler GmbH — Metal Forming Handbook, Springer (standard reference for press and die engineering)
Society of Manufacturing Engineers — SME Tool and Die Technical Group publications on die failure prevention (sme.org)

Suggested Images and Diagrams

Macro photograph of chipping failure — Close-up of punch cutting edge showing angular chip voids. ALT: “D2 tool steel punch showing chipping failure at cutting edge — die failure analysis example”
Galling deposit cross-section micrograph — SEM image of aluminum adhesion deposit on TiN-coated die surface. ALT: “Aluminum galling deposit on stamping die surface under SEM — adhesive wear failure mode”
Fatigue crack beach marks diagram — Schematic cross-section of fatigue fracture surface with beach marks, initiation site, and overload zone labeled. ALT: “Fatigue crack fracture surface diagram showing beach marks — die cracking failure analysis”
Die failure analysis decision tree — Flowchart: failure detected → characterize damage → chipping/galling/cracking branch → root cause analysis steps → correction. ALT: “Die failure analysis decision tree for chipping, galling and cracking in stamping dies”
Clearance vs. life curve — Graph showing die life (strokes) vs. die clearance (% of t) for D2 blanking mild steel, HSLA, and DP780 — illustrating optimal clearance range and failure zones. ALT: “Stamping die life versus die clearance graph for different steel grades”