OEM Lithium Battery Pack Case Mold Maker | Custom Battery Pack Plastic Mould

Systematic mold failure analysis quickly identifies root causes, avoids repeated failure on subsequent molds and reduces production loss. This article sets up Xinfeng mould standardized failure analysis workflow, inspection methods and classification of failure modes.

Step 1: On-site data collection. Record failure cycle count, process parameters, mold temperature, defect location, alloy grade, maintenance history and photos/videos of damaged area.

Step 2: Macro inspection. Observe crack morphology, soldering distribution, surface peeling, deformation and leakage. Judge failure type: thermal fatigue, soldering, nitriding peeling, mechanical overload or corrosion.

Step 3: Non-destructive inspection: UT ultrasonic test, hardness test, surface roughness measurement and dimensional check.

Step 4: Sampling and metallographic analysis for critical cases. Observe microstructure, nitriding layer thickness, crack propagation path and inclusion distribution under microscope.

Step 5: Root cause classification: material defect, heat treatment abnormality, machining residual stress, improper surface treatment, design flaw or on-site process misoperation.

Step 6: Verification and countermeasure formulation. Use simulation or trial mold to validate improvement measures, update mold design specification and process SOP.

Step 7: Document archiving. Add failure case into Xinfeng mould database for future mold design reference.

Common failure mode statistical distribution: thermal fatigue cracks 34%, soldering 30%, nitriding peeling 18%, mechanical deformation 10%, cooling channel corrosion/leakage 8%.

Preventive knowledge transfer: feed failure analysis results back to design, machining, heat treatment and on-site production teams.

### FAQ

Q1: What is the first step of mold failure analysis?
A1: Collect on-site production data, process parameters and failure images.
Q2: What inspection is used to observe mold microstructure and nitriding layer?
A2: Metallographic microscope analysis on sampled mold specimen.
Q3: What accounts for the largest proportion of aluminum casting mold failure?
A3: Thermal fatigue cracks account for 34% of total mold failure cases.

Poor cooling water quality forms scale and corrosion inside cooling channels, gradually reducing cooling efficiency and causing mold temperature drift. Scale blockage accounts for 21% of thermal imbalance issues during mass casting. This article defines water quality index, water treatment and periodic cleaning plan.

Cooling water requirement: total hardness ≤8°dH, pH value 7.2–8.0, chloride ion less than 100 mg/L. Hard water easily precipitates calcium carbonate scale at high mold temperature.

Water filter installation: 50 μm filter before mold cooling inlet to remove suspended particles and rust.

Water temperature control: inlet water maintained at 32–42℃. Water temperature below 30℃ causes excessive thermal shock and accelerates mold thermal fatigue.

Scale formation mechanism: calcium and magnesium ions precipitate when heated on inner wall of cooling channels, forming insulating scale layer, thermal conductivity drops sharply.

Online inhibitor dosing: add low-phosphorus scale inhibitor to circulating water to suppress scale crystallization.

Cleaning cycle: chemical descaling every 6000 casting cycles. Circulate acid-based cleaning agent inside cooling circuit, then fully flush with clean water.

Pressure monitoring for cooling circuit: inlet and outlet pressure difference recorded daily. Pressure rise over 0.05 MPa indicates scale accumulation inside channels.

Corrosion protection: avoid excessive acid concentration during descaling, which will erode cooling channel inner wall and cause water leakage.

After chemical cleaning, hydraulic pressure test at 1.5 times working pressure to verify channel integrity.

### FAQ

Q1: What is the target pH range for mold cooling circulating water?
A1: Cooling water pH should be kept between 7.2 and 8.0.
Q2: How often to perform chemical descaling for mold cooling channels?
A2: Chemical descaling every 6000 casting cycles.
Q3: What is the sign of scale accumulation inside cooling circuit?
A3: Rise of inlet and outlet water pressure difference over 0.05 MPa.

H13 heat treatment is the core process to achieve target hardness, toughness and thermal fatigue resistance. Improper heat treatment causes inconsistent hardness, distortion and early mold failure. This article describes H13 standard heat treatment curve and quality inspection standards.

Preheating: two-stage preheating at 650℃ and 850℃ to reduce thermal gradient inside mold blank, avoid quenching distortion for large mold blocks.

Quenching: austenitizing at 1020–1040℃, hold time 20–30 min per 100 mm thickness. Gas quenching to 150–200℃, cooling rate controlled to prevent thermal stress cracking.

Double tempering: first temper at 560–580℃, hold 2 hours; second temper at 570–590℃. Final hardness target HRC44–49. Single temper cannot fully relieve quenching stress.

Cryogenic treatment after quenching: cool down to -180 ~ -190℃, hold for 2–4 hours. Convert retained austenite into martensite, reduce residual stress and stabilize mold dimension.

Hardness inspection: 5–8 measuring points distributed on cavity surface, hardness deviation within ±1.5 HRC.

Distortion inspection after heat treatment: mold block deformation ≤0.04 mm per 500 mm length. Excessive distortion requires correction and re-machining.

Heat treatment defects: overheating leads to grain coarsening and low toughness; insufficient austenitizing results in low hardness and poor wear resistance.

Weld repaired local region needs local stress relief tempering at 550℃, to match substrate hardness.

Heat treatment batch traceability: record furnace temperature curve, hardness log and distortion measurement report for every mold block.

### FAQ

Q1: What is the austenitizing temperature range for H13 quenching?
A1: H13 quenching austenitizing temperature is 1020–1040℃.
Q2: Why adopt double tempering for H13 mold steel?
A2: Double temper fully relieves quenching residual stress and stabilizes final hardness.
Q3: What is the function of cryogenic treatment after quenching?
A3: Transform retained austenite, reduce residual stress and improve dimensional stability.

Precision CNC machining determines cavity dimensional accuracy, assembly clearance and final casting quality. Poor machining control leads to core offset, uneven wall thickness and assembly interference. This article introduces Xinfeng mould CNC machining sequence, tolerance allocation and inspection standards.

Cavity rough machining: leave 0.4–0.6 mm finishing allowance, control machining vibration to avoid residual stress. Roughing tool path keeps 0.25–0.35 mm depth per cut.

Semi-finish machining: leave 0.12–0.20 mm allowance for final polishing. Check cavity deformation after semi-finishing, especially for large mold inserts over 400 mm.

Finish machining: cavity profile tolerance ±0.03 mm; core pin position tolerance ±0.025 mm. Machining temperature controlled at 22±2℃ to reduce thermal expansion error.

Draft angle machining tolerance: ±0.1°, directly affects ejection drag marks.

Fillet machining: continuous milling for large fillet R≥3.0; small fillet manually polished after CNC. Fillet radius tolerance ±0.05 mm.

Parting surface flatness within 0.02 mm per 500 mm length, to guarantee parting line clearance ≤0.03 mm and prevent flash.

H13 material machining after roughing: stress relief tempering before finish machining to release cutting residual stress, avoiding cavity deformation after final machining.

CMM inspection after finish machining: full 3D scanning of cavity, core pins, cooling holes and vent slots, generate dimensional deviation report.

Electrode design for EDM: used for deep narrow rib cavities where milling tool cannot reach. EDM surface must be polished to Ra0.8 before nitriding.

Machining marking: each insert engraved with part number, serial number and heat treatment batch for full traceability.

### FAQ

Q1: What finishing allowance is reserved after mold semi-finish machining?
A1: 0.12–0.20 mm finishing allowance left before polishing.
Q2: What is flatness requirement of mold parting surface?
A2: Parting surface flatness controlled within 0.02 mm per 500 mm length.
Q3: Why stress relief tempering after H13 rough machining?
A3: Release cutting residual stress and prevent cavity deformation after finish machining.

Venting system directly discharges trapped air, release agent decomposition gas and hydrogen. Insufficient venting creates cold shut, gas pores and oxide defects. This article defines vent dimension calculation rules, layout principles and maintenance plan for LPDC and gravity casting molds.

Total vent area calculation rule: total vent cross-sectional area equals 0.8–1.2% of casting projected area. Below 0.8% easily leads to gas trapping; over 1.2% increases flash risk.

Vent slot depth classification:

- Thin wall casting: 0.10–0.14 mm
- Medium wall structural casting:0.12–0.16 mm
- Thick boss region:0.14–0.18 mm

Vent slot width 8–15 mm per vent segment. Vent length controlled within 6–10 mm, followed by expanded exhaust cavity 2–4 mm deep to collect aluminum residue.

Vents placed at melt end filling positions, top of ribs and high point of cavity. Avoid placing vents directly at high speed melt impact zone.

Vent inserts are adopted for high wear vent locations. Replaceable vent inserts reduce maintenance time by 42% and avoid reworking whole cavity.

Vent cleaning cycle: gravity mold every 110–130 cycles; LPDC mold every 180–210 cycles. For high oxide alloy A206, shorten cleaning cycle to 100 cycles.

Vent inspection items during maintenance: slot depth, aluminum residue blockage, surface soldering and crack. Replace insert if vent depth wears over 0.03 mm.

CPC mold vent design needs to match argon flow field. Excessive vent area causes argon leakage and damages inert gas protection.

Debris from vent clogging may be pressed into casting surface and form foreign inclusion defects.

### FAQ

Q1: What is the recommended total vent area ratio for aluminum casting mold?
A1: Total vent cross-sectional area should be 0.8–1.2% of casting projected area.
Q2: Where should mold vents be arranged?
A2: Vents are arranged at melt final filling positions, rib tops and cavity highest points.
Q3: How often to clean vents for A206 alloy casting?
A3: Vent cleaning cycle shortened to every 100 casting cycles for A206 alloy.