Aluminum Die Casting Checklist Guide

1. General Information
• Company profile and certifications (ISO 9001, IATF 16949, ISO 14001, etc.)
• Years of experience with aluminum die casting
• Alloys used (e.g., EN AB-46000, 47100, 226D)
• Monthly/yearly capacity and current utilization
• Industries served (automotive, electrical, etc.)
• In-house tool shop or outsourced mold maintenance?

2. Raw Material & Melt Management

• Alloy certificate & traceability (check recent lot documentation)
• Scrap content % in melt (target <20–30%)
• Melt temperature control (typically 660–700°C for Al)
• Furnace cleanliness and maintenance schedule:
Furnace Cleanliness: What & Why
Why it's important:
o Prevents aluminum oxide buildup (which can contaminate melt).
o Reduces hydrogen pickup from moisture in dross or residues.
o Prevents damage to refractory lining.
o Improves energy efficiency and reduces downtime.
What is cleaned:
➢ Bath surface (dross, oxides, slag)
➢ Refractory walls and corners
➢ Thermocouple protection tubes
➢ Tapping channels and launders
➢ Heating elements (gas burners or electric resistors)

• Daily Maintenance Tasks

o Usually performed at the start or end of each shift.
o Skim dross (oxide layer) from the melt surface using a skimming tool or rake.
o Inspect melt surface for contaminants or crust formation.
o Check furnace lid or cover to ensure it is closed (prevents heat loss and oxidation).
o Clean around the charge door and tap hole areas.
o Check thermocouple for corrosion or metal sticking.

Tip: Always preheat skimming tools to avoid chilling the melt or introducing moisture (which can cause hydrogen porosity).

• Weekly Maintenance
o Clean furnace walls and corners where oxides tend to build up.
o Check refractory lining for cracks, spalling, or wear.
o Clean the launder/tapping system if used (with scraper or vacuum system).
o Clean burner tips or heating elements from soot or oxide deposits.
o Visually inspect charging systems for aluminum residues.

• Monthly or Scheduled Maintenance

o Drain furnace (if required) and manually clean the bath floor of settled oxides or inclusions.
o Inspect and possibly replace refractory lining (patch repair or full relining every few months depending on usage).
o Calibrate or replace thermocouples.
o Clean air/gas filter if burner system is used.
o Check electrical connections in electric furnaces.

• Safety Measures
o Operators must wear:
o Face shield, gloves, aluminized apron
o Respirator if dross dust is airborne
o Tools should be preheated and dry (never insert wet tools)
o Use vacuum systems or HEPA-filtered extractors if dust removal is done

Best Practices
❖ Use flux only if needed (e.g., cleaning or covering flux for surface dross).
❖ Log maintenance in a furnace logbook: date, operator, temperature trends, cleaning actions.
❖ Regularly monitor melt quality indicators like density index or hydrogen testing — sudden deterioration might point to poor
furnace conditions.

• Dross removal and skimming frequency

Dross is the solidified layer of aluminum oxides and impurities that forms on the surface of molten aluminum due to oxidation. If not removed:
o It re-enters the melt during ladling
o Causes inclusions in castings
o Increases hydrogen pickup
o Degrades mechanical properties
Recommended Skimming Frequency
Stage Skimming Frequency Notes
Holding furnace Every 30–60 minutes Especially if no flux or automated cover system is used
Before each ladle transfer Every time before ladling Essential to avoid pouring dross into the shot sleeve
After alloy charging Immediately after melting During alloying or addition of scrap/ingots
Before flux treatment Once, then again after degassing Ensures cleaner melt
If dross buildup is visible Skim immediately Don’t wait for schedule — visual cues matter

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 Best Practices
❖ Use preheated skimming tools (avoid chilling the melt)
❖ Skim with circular or sweeping motions
❖ Do not stir the melt aggressively — it pulls dross into bath
❖ Use cover flux to slow oxidation (optional)
❖ Store dross separately — it contains usable metal (can be recovered in recycling)
Automation
If you use automated ladles, integrate a skimming step before each transfer using:

❖ Mechanical skimmers
A mechanical arm with a scraping blade or scoop that is lowered into the furnace or holding bath to physically push dross
away from the metal ladling zone or extract it.
Components:
✓ Rigid or articulated arm with:
➢ Skimming plate, rake, or scoop
✓ Actuated by servo motor, pneumatic, or hydraulic system
✓ Often integrated with PLC to trigger skimming every X cycle or time
How it Works:
1. Skimmer enters the melt at shallow depth (to avoid disturbing clean metal)
2. Sweeps across the surface
3. Pushes dross into a dross collection box or skims it off
4. Retracts automatically
Benefits:
✓ Reduces manual labor
✓ Increases repeatability
✓ Avoids human errors (e.g. stirring the bath)
✓ Minimizes thermal losses during skimming

❖ Rotating disk
Primary Function:
✓ Used mostly for rotary degassing, but with design add-ons, these systems can simultaneously help skim dross by
creating turbulence and pushing oxides to the periphery.
How it Works:
✓ A graphite or ceramic-coated disk rotates at high speed (~200–600 rpm)
✓ Inert gas (argon or nitrogen) is bubbled through the disk into the melt
✓ This motion forces oxides and impurities upward, often to the sides of the vessel
Note:
✓ Not a true skimming tool — but helps concentrate dross for easier skimming
✓ Disk units are complementary to manual or mechanical skimmers

❖ Paddle system
A rotating flat paddle blade, usually made of ceramic-coated metal or graphite, mounted on a robotic arm or turret.
How it Works:
✓ Paddle enters at shallow depth
✓ Rotates and pushes surface dross in a controlled direction (to a collection trap or overflow zone)
✓ Can be integrated with an automated ladler — skimming just before ladling action

Benefits:
✓ Minimal turbulence (gentler than rotary disks)
✓ Excellent for pre-ladle skimming
✓ Can be used in open crucibles or holding furnaces
✓ Works well in shallow melt baths

Integration in Automated Ladlers

In modern die casting cells:
➢ Skimming step is automated right before ladling
➢ Robotic ladle may pause → skimmer clears dross → ladler dips and pours
➢ Sequence controlled via PLC or robot teach pendant
➢ Prevents dross entrainment into shot sleeve — key for reducing porosity
Pro Tips
➢ Always preheat skimming tools to avoid thermal shock
➢ Ensure skimming blade depth is shallow (only upper 5–10 mm of melt)
➢ Use ceramic or graphite-coated tools to resist corrosion
➢ Consider robotized integration with ladling cycle for consistency
➢ Keep a skimming log by shift or lot (especially during audits)
➢ If using rotary degassing or flux treatment — always skim before and after
➢ Poor skimming correlates directly with surface defects and porosity

• Degassing equipment (e.g., rotary degasser or tablets)

Hydrogen gas is the main dissolved impurity in molten aluminum, and if not removed properly, it causes porosity, poor mechanical properties,
and leakage issues in cast parts.
Why Degassing is Critical in Aluminum HPDC
✓ Aluminum absorbs hydrogen during melting from:
➢ Moisture in the atmosphere
➢ Humid charge material or tools
➢ Combustion products from burners
✓ Hydrogen is soluble in liquid Al, but not in solid → it forms gas porosity during solidification
✓ Even a small increase in hydrogen content dramatically reduces:
➢ Tensile strength
➢ Pressure tightness
➢ Machining quality

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 Degassing Methods Overview

Method How It Works Automation Level Common Use

Rotary degasser Gas bubbled through spinning shaft High Foundries, HPDC
Degassing tablets Chemical reaction releases gas to displace H Low Low-mid volume
Bubbling lance Inert gas injected via graphite lance Medium Small shops
Vacuum degassing Reduced pressure over melt Medium Small shops

4.6 Rotary Degasser – Industry Standard for HPDC

How It Works:
o A rotating shaft with a graphite impeller is submerged in the melt
o Inert gas (usually N₂ or Ar) is introduced through the shaft
o The impeller disperses fine bubbles throughout the melt
o Hydrogen diffuses into bubbles and exits the bath with the rising gas

Technical Parameters:
Parameter Typical Value
Rotation speed 300–600 rpm
Treatment time 5–15 minutes (varies with bath size)
Gas flow rate 10–30 liters/min
Shaft material Graphite, coated graphite, SiC
Advantages:
o Highly efficient hydrogen removal
o Creates small, uniform gas bubbles
o Also helps float oxides and inclusions
o Can be combined with flux injection
Risks / Maintenance:
o Graphite impellers wear and erode (every 1–2 months)
o Shaft must be preheated to avoid thermal shock
o Must avoid splashing (gas flow too high = turbulence)

4.6 Degassing Tablets (Hexachloroethane, etc.)

How It Works:
o Tablets are dropped into the molten metal
o They release chlorine or fluorine-based gases (e.g., Cl₂) that displace hydrogen
o Gases rise, carrying hydrogen and some inclusions
Common Compounds:
o Hexachloroethane (C₂Cl₆)
o Commercial products: Degasal, FoundryFlux, Coveral
Advantages:
o Cheap, easy to use
o No equipment required
o Good for small furnaces or holding pots
Limitations:
o Less consistent than rotary degassing
o Creates fumes – requires fume hood or ventilation
o Leaves more residue/slag
o Toxic byproducts (Cl₂ gas → irritant)
Environmental restrictions in some countries (e.g., EU) limit their use

4.6 Gas Bubbling Lance (Manual Inert Gas Injection)

How It Works:
o A perforated graphite tube is submerged in the melt
o Inert gas (Ar/N₂) is bubbled in manually
o Hydrogen diffuses into bubbles and escapes
Advantages:
o Simple, inexpensive
o No rotating parts
o Can be used with fluxes
Disadvantages:
o Large bubbles → less surface area → lower efficiency
o Limited depth reach
o Graphite lances wear out quickly
o Operator-dependent results

4.6 Melt Quality Verification – Density Index

After degassing, test melt cleanliness using:
Density Index (DI):
o Sample is poured into 2 molds: one under vacuum (~80 mbar), one in air
o Weigh both samples and calculate:

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 Best Practices for Degassing
o Always skim dross before and after degassing
o Use argon instead of nitrogen if alloy contains Mg or Sr (to prevent reaction)
o Preheat rotary shaft to avoid cracking
o Combine degassing with flux treatment (e.g., Cover Flux 21 or similar)
o Log treatment time, gas flow, and DI values

• Melt quality testing:

These tests are essential for porosity control, mechanical integrity, and process validation in aluminum die casting, especially for structural
or pressure-tight components.
WHY IT MATTERS
• Hydrogen is the most critical gas impurity in molten aluminum.
• It dissolves in liquid Al but precipitates as pores during solidification.
• Poor melt quality leads to:
o Gas porosity
o Reduced tensile strength
o Leakage in pressure-tight parts
o Welding or anodizing issues
1. Hydrogen Testing Methods

A. Straube-Pfeiffer Test (Reduced Pressure Test – Manual)

Type: Manual / Semi-quantitative
Purpose: Evaluate hydrogen-induced porosity visually
Procedure:
1. Pour molten aluminum into a small crucible.
2. Place crucible into a vacuum chamber (typically ~80 mbar).
3. Solidify metal under vacuum.
4. Break sample and visually evaluate porosity on fracture surface.
Interpretation:
Pore Size / Count Melt Quality
Minimal to none Good
Many fine pores Moderate
Coarse or interconnected pores Poor
Advantages:
o Inexpensive, fast
o Good for on-floor checks
Limitations:
o Subjective (visual grading)
o No numerical hydrogen value
o Affected by cooling rate and operator judgment

B. ALSCAN (Aluminum Hydrogen Analyzer)

Type: Digital / Quantitative
Purpose: Accurately measure dissolved hydrogen in molten aluminum
Principle:
o Uses closed-loop gas sampling via solid electrolyte sensor or carrier gas
o Measures partial pressure of hydrogen in melt (similar to an oxygen probe in steel)

Measurement Output:
o Reports [H] in ppm (parts per million)
Typical value: <0.15 ppm is excellent
Acceptance Ranges:

Application Max H₂ Content (ml/100g Al)

General HPDC ≤ 0.15
Leak-tight parts ≤ 0.10
Aerospace castings ≤ 0.07

Steps:
1. Insert sampling probe into molten metal (at stable temperature and depth)
2. Wait for equilibrium (~2–5 minutes)
3. Read hydrogen level on analyzer display
4. Remove probe and log data
Advantages:
o Objective and accurate
o Tracks degassing effectiveness
o Required for OEM approval and audits
Limitations:
o Costly equipment
o Requires calibration and maintenance
o Probe wear due to metal contact
Popular Systems:
o ALSCANTM by ABB/ABB Foundry Solutions
o MKTEK or MELTlab hydrogen analyzers

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 2. Density Index Test (DI Test)
Also called Porosity Index or Bifilm Index in some standards.
Goal: Compare metal density in air vs. in vacuum to reveal gas content and bifilm inclusions.

Procedure:
5.3 Preheat two small steel molds to ~200–250 °C
5.3 Pour molten aluminum from the same ladle into:
o Mold A under atmospheric pressure
o Mold B under vacuum (~80 mbar)
5.3 Allow both samples to cool
5.3 Weigh each solidified sample:
o Air sample → Wa
o Vacuum sample → Wv
5.3 Use this formula:

DI (%) Melt Quality Action Needed?

0–2% Excellent None
2–5% Acceptable Monitor / optimize flux
>5% Poor (Gas or Oxides) Re-degas & skim
>10% Critical Reject melt, reprocess

Advantages:
o Simple and cost-effective
o Detects both hydrogen and inclusions (bifilms)
o Ideal for routine process control
Limitations:
o Affected by pouring consistency, mold temp
o Manual weighing = potential human error

Best practices for melt quality control

Practice Purpose
Always skim before sampling Remove floating dross
Use dedicated sampling ladle Avoid contamination
Preheat molds and tools Prevent chilling, shock
Record test results by lot Enable traceability
Calibrate balances & analyzers Accuracy

Comparison: ALSCAN vs. DI vs. Straube-Pfeiffer

Feature ALSCAN Density Index (DI) Straube-Pfeiffer

Measurement type Direct, quantitative Indirect, comparative Visual/Semi-quantitative
Measures H₂ concentration (ml/100g) Mass difference → porosity Visual porosity under vacuum
Equipment cost High Low–Medium Low
Use case Precise control, traceability Shop-floor QA Quick indication
Test time ~5–10 minutes ~5–10 minutes ~5 minutes
Sensitivity Very high Moderate Moderate

• Melt Holding furnace usage and temperature consistency:

This is a critical part of melt management, especially when working with high-integrity parts or requiring tight control of porosity and
mechanical properties.

Why Is It Important?
o Maintains melt quality by minimizing oxidation and hydrogen absorption
o Ensures temperature stability for consistent injection conditions
o Allows buffering between melting and casting, improving process flow
o Minimizes thermal shock to the die and extends die life
o Prevents cold shuts, incomplete filling, and porosity

Optimal Temperature Ranges

Alloy Type Holdin temp Notes

EN AB-46000 / 47100 660–680 °C Ideal balance between fluidity and dross formation
Silumin 226D 670–690 °C Slightly higher to maintain flow into thin-wall parts
Over 700 °C Avoid Increases oxidation, dross, hydrogen absorption

Temperature should be stable within ±5 °C to ensure casting repeatability.

Temperature Control Methods:
1.5 Thermocouples (Type K or S)
o Inserted in the bath or in protective sheaths
o Must be regularly calibrated and replaced

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 2.5 Digital PID Controllers
o Setpoint and actual temperature shown on a display
o Can be linked to alarms if deviation exceeds limits
3.5 Data Logging Systems
o Track temperature trends and enable traceability

Common Problems & Effects

Problem Cause Effect

Temperature fluctuation Poor insulation, faulty thermocouple, PID drift Variation in casting fill, porosity, flash
Overheating Operator error, controller failure More oxides, higher hydrogen, die erosion
Cold melt Excessive skimming, poor transfer Short shot, cold shut, weak mechanical properties

Best Practices:
o Preheat furnace before adding melt (reduce thermal shock)
o Use protective cover flux to reduce oxide formation
o Skim surface oxides regularly
o Avoid frequent lid opening — use automated dosing units
o Perform weekly calibration check of thermocouples
o If transferring melt: preheat ladles, avoid turbulence
Advanced Options (Optional but Recommended):
o Automated melt level sensors to trigger refilling
o Integrated degassing (rotary impeller in holding furnace)
o Nitrogen blanketing to reduce hydrogen absorption

3. Tooling and Mold Setup

3.1 Die material and coating type

Die steel must have:
• High thermal fatigue resistance
• Good toughness and hot strength
Common grades:
• H13 / X40CrMoV5-1 (most widely used for Al HPDC)
• 1.2344 / 1.2367 / SKD61 (depending on region)
Surface treatments & coatings:
• Nitriding – improves wear resistance and lifespan
• PVD coatings (e.g., CrN, AlCrN) – reduce soldering and erosion
• TD coating (Thermal Diffusion) – high surface hardness (~2000 HV)
Checkpoints:
• Tool steel grade and supplier certificate
• Coating type and application method
• Coating thickness and adhesion testing

3.2 Mold Maintenance Schedule and Records

Molds degrade due to:
• Thermal fatigue (heat checking)
• Erosion (from molten metal)
• Soldering (metal sticking to die)
Best practices:
• Cycle-based maintenance: e.g. every 5,000–10,000 shots
• Visual inspection: ejector pins, sliders, vents
• Non-destructive testing: dye penetrant for micro-cracks
• Spare parts inventory: pins, inserts, cores
Checkpoints:
• Maintenance logs per cavity/inserts
• Preventive maintenance plan
• Records of insert change intervals

3.3 Venting Layout and Cleaning Procedure

Vents allow trapped air to escape during injection.
Poor venting = air entrapment = porosity or cold shuts
Types:
• Venting gaps at parting lines (~0.02 mm deep)
• Insert vents or overflow vents at cavity ends
Cleaning:
• Done every shift or after set number of shots
• Use copper brushes or compressed air
• Vacuum or monitor carbon/oil buildup
Checkpoints:
• Are vents positioned at last fill areas?
• Vent dimensions checked and logged?
• Are vents cleaned routinely?

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 3.4 Overflow and Vacuum Vent Design
Overflow collects cold metal and entrapped gas.
Vacuum system (if present):
• Uses vent blocks with filters
• Must reach <50 mbar before shot
Design rules:
• Volume of overflow ~10–15% of casting
• No sharp corners
• Overflow returns for metallurgical evaluation
Checkpoints:
• Overflows properly dimensioned and located?
• Vacuum system functionality and leak checks?
• Presence of vent plugs and filters?

3.5 Parting Line Condition and Flash Management

The parting line is prone to:
• Flashing (molten metal leaks through gaps)
•
• (leading to dimension shifts)
Root causes of flash:
• Die clamping force too low
• Die wear at parting surface
• Poor alignment
Prevention:
• Laser or feeler gauge inspection
• Realignment of platens
• Polishing or grinding sealing surfaces
Checkpoints:
• Check for flash marks on parts
• Check die closing force vs required
• Parting surface condition (pits, wear, erosion)

3.6 Thermal Control

Uneven temperature = internal stresses, distortion, shrinkage porosity
Control methods:
• Cooling circuits (water, oil, or hybrid)
• Baffles or bubblers in cores
• Mold temperature controllers (MTCs) with flow and temp sensors
• Thermal imaging of mold surface during production
Key parameters:
• Die surface temp: ~200–250 °C
• Oil circuit temp: ~80–120 °C
• Water flow rate: balanced across zones
Checkpoints:
• Mold cooling layout map exists?
• Flow rate/temperature monitored in real-time?
• Any known hot/cold spots from thermal scan?

Pro Tip: Mold Start-Up Procedure

When starting cold:
4.4 Preheat mold with external heaters or dry runs
4.4 Gradually increase injection speed
4.4 Discard first 20–30 parts to stabilize mold temp

Summary Checklist Table

Point Key Checks

Die material/coating Steel grade, coating type, test results
Mold maintenance Schedule, logs, replaced parts
Venting Layout, depth, cleanliness
Overflow/Vacuum Placement, function, pressure levels
Parting line Flash, wear, alignment
Thermal control Circuit layout, flow/temp control, imaging

4. Casting Machine and Parameters

4.1 Machine Type (Cold Chamber, Tonnage)
Types:
• Cold chamber machines are standard for aluminium due to high melting temps (above 600 °C)
• Tonnage range typically:
o Small parts: 200–400 tons
o Medium: 400–800 tons
o Large parts: 1000–3000+ tons

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 Key Considerations:
• Is the machine tonnage adequate for projected part + runner area?
• Machine clamp force = ~4–6 tons/cm² of projected area
Example:
Projected area = 300 cm² → Minimum clamp force ≈ 1800 tons

4. Injection Stages (Slow Shot, Fast Shot, Intensification)

High-pressure die casting typically uses 3 stages:
i. Slow Shot (1st stage)
➢ Fills the shot sleeve slowly to avoid air entrapment
➢ Speed: ~0.1–0.5 m/s
ii. Fast Shot (2nd stage)
➢ Accelerates piston to fill cavity quickly
➢ Speed: 2–6 m/s (sometimes >8 m/s for thin parts)
➢ Must be fast enough to avoid premature solidification
iii. Intensification (3rd stage)
➢ High pressure (~400–1200 bar) is applied after filling
➢ Reduces porosity by compressing the solidifying metal
Key Controls:
➢ Switch-over point from slow to fast stage (based on piston position or pressure)
➢ Start of intensification: typically, just before the cavity is fully filled

iv.Control System (Manual, Semi-Auto, Fully Auto)

• Manual: older systems, operator input for most steps
• Semi-auto: automated injection, but manual ladling or spraying
• Fully automatic: includes robot ladle, sprayer, extractor, integrated monitoring
What to look for:
• Programmable logic controller (PLC) with parameter recipes?
• Alarm system for deviation in key values.
• Is production data stored or logged?

4.4 Parameters Monitored and Recorded

These are critical for repeatability and traceability.

Key Parameters

Parameter Typical Range Purpose

Shot sleeve temp 150–250 °C Prevent cold metal flow
Slow shot speed 0.1–0.5 m/s Reduce turbulence
Fast shot speed 2–6 m/s Ensure full cavity fill
Intensification pressure 400–1200 bar Reduce porosity
Switch-over point Position or pressure-based Optimize fill quality
Metal temperature 660–690 °C Maintain flow and quality
Die temperature 200–250 °C Avoid cold shut or soldering

Checkpoints:
• Does the system log these parameters automatically?
• Can machine graphs be viewed per cycle?
• Alarms set on out-of-tolerance values?

4.5 Real-Time Monitoring and Alarms

Modern HPDC machines should have:
• Live display of piston velocity and pressure
• Cycle time tracking
• Trend analysis of key parameters
• Alarms and interlocks for:
o Piston position deviation
o Metal temp out of spec
o Injection delay or incomplete fill
o Cooling water/oil malfunction
Ideal Setup:
• Touchscreen HMI with graphical interface
• Ethernet-connected for data export
• Automatic machine stop on critical deviation

4.6 Lubrication System (Manual/Spray/Automatic)

Die lubrication affects:
• Surface finish
• Part ejection
• Die life
Methods:
• Manual spray – operator with handheld nozzle
• Semi-auto spray arm – programmable pattern
• Fully automated robotic spray – zoned spraying

Lubricants:
• Water-based with graphite/silicone/oil content
• Proper dilution ratio (e.g., 1:30 to 1:100)
Checkpoints:

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 • Uniform spray pattern?
• Lubrication time per shot?
• Coverage of critical zones (ejector side, cores, sliders)?
• Are mould cavities dry before injection?

Common Injection Defects Due to Poor Setup

Issue Possible Cause

Short shot Fast shot speed too low, cold melt
Flashing Clamp force too low, worn parting line
Porosity Low intensification pressure, gas entrapment
Cold shut Die too cold, shot speed too slow
Soldering Overheated die surface, poor lubricant

Monitoring Matrix Example

Feature Setpoint Measured Alarm Tolerance

Metal Temp 675°C 672°C ±5°C
Die Temp 220°C 219°C ±10°C
Fast Shot Speed 4.5 m/s 4.6 m/s ±0.3 m/s
Intensification Pressure 950 bar 948 bar ±50 bar

5. Lubrication & Ejection

Effective lubrication and ejection are essential to:
• Prevent sticking and soldering
• Protect the die surface
• Enable clean part ejection
• Prolong die life
• Reduce cycle time

5.1 Die Lubricant Type and Concentration

Most aluminium die casting lubricants are water-based emulsions containing:
• Graphite, synthetic oils, or silicone components
• Additives for anti-stick, wetting, and die cooling

Key Properties of Good Die Lubricant

Property Ideal Value / Behavior

Flash Point >200 °C (for oil-based components)
pH 8–10 (mildly alkaline for stability)
Dilution ratio 1:30 to 1:100 (depending on application)
Solid content 5–10% (too much causes buildup)
Cooling rate Moderate, prevents thermal shock
Carbon residue Low — minimizes soot buildup
Lubricity High — especially for cores and sliders
Biocide content Yes — to prevent microbial growth

Types of Lubricants

Type Composition Best For

Graphite-based Water + graphite flakes Prevent cold metal flow
Silicone-based Water + silicone oils Good surface finish, thin-wall parts
Synthetic polymer Water + esters/polyethers Clean die, minimal residue
Oil-based Hydrocarbons Older systems, risky due to fire hazard

Always check compatibility with die coating (e.g., CrN can be sensitive to some chemistries).

5.2 Spray Pattern, Coverage, and Timing

Correct application is as important as the lubricant itself.

Best Practices:
• Spray must cover entire cavity, including core pins and sliders
• Spray angle ~45° for deep areas
• Avoid over-lubrication → causes porosity
• Under spray → causes soldering and ejection marks
• Spray delay (dwell time) ~1–2 seconds after cavity opens

Automation Levels:

Type Description Advantage

Manual Hand-held by operator Flexible, but inconsistent
Semi-auto Arm moves across die Uniform, but requires tuning
Full-auto (robot) Zoned, programmable Precise, best for high-volume

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 5.3 Ejection System Condition (Pins, Cylinders)
Ejection failure causes:
• Part damage
• Tool wear
• Increased cycle time
Key Components:
• Ejector pins: hardened tool steel (check for wear, galling)
• Hydraulic or pneumatic cylinders: should be leak-free
• Return springs or plates
• Ejector plate movement: must be smooth and aligned
Best Practices:
• Use ejector lubrication spray or solid film lubricant
• Avoid dry pins (risk of sticking or galling)
• Replace worn or scored pins during scheduled maintenance
• Check vent holes behind ejectors for trapped gas

5.4 Drying of Cavity Before Shot (Air Blow-Off)

After spraying, any residual water can:
• Flash to steam → porosity
• Cause hydraulic defects in the metal
• Erode die surface if trapped
Best Practices:
• Blow with dry compressed air (≥6 bar)
• Target narrow areas: cores, threads, ejector pockets
• Set air blow duration: 2–5 seconds, adjustable by zone
• Confirm dryness with thermal camera if available
Avoid over-drying leading to hot spots and die wear.

Example of a Recommended Die Lubricant (Technical Profile)

Product: Chem-Trend SL-8801 (commonly used for Al HPDC)

Property Ideal Value / Behavior

Type >200 °C (for oil-based components)
Recommended dilution 8–10 (mildly alkaline for stability)
Appearance 1:30 to 1:100 (depending on application)
Lubricant base 5–10% (too much causes buildup)
Cooling rate Moderate, prevents thermal shock
Carbon residue Low — minimizes soot buildup
Lubricity High — especially for cores and sliders
Biocide content Yes — to prevent microbial growth

Key Benefits:
• Excellent release for complex parts
• Minimal buildup
• Low porosity risk if properly applied
• Good wetting of fine features (threads, logos, etc.)

Summary Checklist for Lubrication & Ejection

Point Check (Yes / No)

Lubricant type and dilution
Uniform spray coverage
Lubrication zones defined
Ejector pins lubricated
Blow-off time sufficient
Dry cavity confirmed
Ejection cycle smooth
Spray robot/program audited

6. QUALITY CONTROL in ALUMINUM DIE CASTING

6.1 First Article Inspection (FAI)
Purpose:
Verify that the first part off the tool meets all dimensional, visual, and functional requirements.
How It’s Done:
• The first part after tool setup is:
o Cleaned
o Visually inspected
o Measured against drawing/specs (using calipers, micrometers, or CMM)
• All critical-to-quality (CTQ) dimensions are checked and documented.
• FAI report is signed off before continuing mass production.
Checklist:
• Is there an FAI template?
• Are results archived and signed by QA?
• Are deviations reviewed and corrected before mass run?

6.2 In-Process Inspection

What It Covers:
• Performed periodically during production
• Monitors dimensional drift, weight change, surface defects, and cavity-to-cavity variation

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 Methods:

Test Tool Used Measured Alarm Tolerance

Weight check Precision scale Every 20–50 pcs Deviation may indicate incomplete fill
Visual inspection Trained inspector Every cycle Surface defects, flash, cold shut
Dimensional check Caliper, gauge, or CMM Every 1–2 hours Lengths, hole positions, diameters

Often documented in an SPC chart for statistical control.

6.3 X-Ray / Non-Destructive Testing (NDT)

Purpose:
To detect internal defects: porosity, cold shuts, misruns, inclusions
Equipment:
• Digital X-ray cabinet
• Manual fluoroscopy
• Computed Tomography (CT) for high-value parts
How It’s Done:
• Castings are placed in an X-ray chamber.
• Images are taken of key cross-sections.
• Defects are classified using a grading system (e.g., ASTM E505).
• CT scanning creates 3D models to analyze internal geometry and voids.
Best Practices:
• Use a standard sample with known defects as a reference.
• X-ray sampling rate is based on severity of application (e.g., 100% for safety parts).

6.4 Metallography and Sample Preparation

Purpose:
To evaluate:
• Grain structure
• Porosity
• Phase distribution
• Inclusion content
How It’s Done:
1. Section the casting (usually with diamond saw)
2. Mount in resin (if needed)
3. Polish through graded abrasives (240→1000 grit, then diamond paste)
4. Etch (e.g., Keller’s reagent for Al alloys)
5. Examine under optical microscope or SEM
Measurements:
• Porosity % (area fraction)
• Dendritic arm spacing (DAS)
• Secondary phase segregation
Often required for PPAP or OEM audits.

6.5 Mechanical Property Testing (UTS, Yield, Elongation)

Goal:
Verify that the casting meets strength specifications.
Test Types:
• Ultimate Tensile Strength (UTS)
• Yield Strength (YS)
• Elongation at break (%)
• Hardness (HV, HB)
How It’s Done:
• Test bars are cast in a test mould or machined from casting.
• Universal tensile machine is used:
o Pulls sample at a constant rate
o Measures load vs extension
• Elongation is measured using extensometer or by marking gauge length
Standards:
• ASTM E8 for tensile testing
• EN ISO 6892-1 for metallic materials
For HPDC, elongation is typically low (1–5%) due to porosity.

6.6 Hardness Testing (HV5 or HV10)

Purpose:
Assess surface or bulk hardness — linked to heat treatment and alloy phase.
How It’s Done:
• Vickers hardness test (HV5 or HV10)
• Indenter applies 5 or 10 kgf load for 10–15 sec
• Diagonal of indentation is measured
• Value calculated from force/area
Best Practices:
• Use polished and flat surface
• Repeat at multiple locations (edge, centre, thick/thin walls)

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 Acceptable Ranges

Alloy Typical Hardness

EN AB-46000 70–100 HV
EN AB-47100 80–110 HV
EN AB-44300 85-95 HV
226D (with aging) 100–130 HV

6.7 Leak Testing (for Pressure-Tight Parts)

Required for:
• Housings
• Valve bodies
• Hydraulic/pneumatic parts
Types of Tests:

Method How It Works

Air pressure decay Pressurize part with air, monitor pressure drop
Water immersion ("bubble test") Pressurize and submerge in water
Helium leak detection Very sensitive, lab-level method

Notes:
• Include sealing plugs or plates for testing
• Define acceptance limits in mbar/s or cc/min
• Automate in line if 100% testing is needed

6.8 Statistical Process Control (SPC)

Purpose:
To detect trends before parts go out of spec.
Key Tools:
• X-bar / R chart
• Cp / Cpk values (process capability)
• P-chart (for defect rate tracking)
What’s Monitored:
• Part weight
• Key dimensions (e.g., hole Ø, length)
• Porosity rating
• Visual defect count
SPC allows predictive control, not just reactive.

6.9 Defect Tracking and Analysis (8D, Pareto, Fishbone)

What It Is:
Root cause analysis when defect rates increase, or customer complaint arises.
Tools Used:

Tool Function
Pareto chart Prioritize most frequent defects
8D Report Structured problem-solving (used in automotive)
Ishikawa / Fishbone Visualize root causes (Man, Machine, Method, Material)

Example 8D Flow:
1. Team setup
2. Problem description
3. Interim containment
4. Root cause analysis
5. Corrective actions
6. Verification
7. Prevent recurrence
8. Closure

Summary: Key Quality Control Activities

Control Type Frequency Tools

FAI At setup Calipers, CMM, visual
In-process Every shift / hourly Gauges, weight scale
X-Ray / CT Periodic / 100% for safety X-ray cabinet
Metallography Per batch Microscope, polishing machine
Tensile/UTS Every lot / PPAP Universal tester
Hardness Random sample Vickers HV10
Leak Test 100% for pressure parts Air or water setup
SPC Live or daily Control charts
Defect Analysis As needed 8D, Pareto

7. POST-PROCESSING in Aluminium Die Casting

7.1 Trimming Process (Manual, Semi-Auto, Press Type)
Purpose: Remove excess material from parting lines, overflows, runners, and flash.

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 Methods:

Type Description Best for

Manual Hand tools, air saws, files Prototypes, low volume
Hydraulic/Pneumatic Trimming Press Die-trimming using matched steel tools Medium–high volume, consistent geometry
CNC Milling/Grinding Burr removal and edge rounding Tight tolerances, complex geometries

Best Practices:
• Check for burrs, rough edges, or gouges
• Validate trim die alignment regularly
• Monitor trim die wear (can damage cast part)
• Evaluate part deformation from trimming force

7.2 Surface Finishing (Shot Blasting, Vibratory, etc.)

Purpose: Improve surface appearance, remove scale/oxide, deburr, and prep for coating.

Methods:

Type Description Application

Shot Blasting Steel/aluminum balls blasted at parts in a chamber Deburring, rough surface prep
Vibratory Finishing Parts tumbled with ceramic/plastic media Smoothing, polishing
Sand Blasting Abrasive grit (Al₂O₃, glass beads) under pressure Strong cleaning, surface roughening
Barrel Tumbling Batch parts in rotating drum with abrasives Internal edge finishing, small parts

Key Parameters:
• Media type and size
• Exposure time
• Part orientation
• Contamination control
Quality Checks:
• Surface Ra (roughness average) measurement
• No media stuck in holes or threads
• Visual inspection for uneven finish or impingement

7.3 Heat Treatment (If Applicable – T5, T6, etc.)

Not all Al die castings are heat treated, especially if high porosity is present (risk of blistering).

Common Treatments:

Type Process Purpose

T5 Artificial aging at ~180–200°C Stabilize dimensions, boost strength
T6 Solution heat treatment + aging Maximize mechanical properties (for low-porosity castings only)
Annealing ~350°C Stress relief

Controls:
• Furnace calibration (ISO 9001 / CQI-9)
• Soak time and ramp rate
• Sample coupons or representative parts
Avoid heat treating die castings with interdendritic porosity unless tested and verified.

7.4 Machining (In-House or Subcontracted?)

Purpose: Achieve tight tolerances, threads, sealing surfaces, mating interfaces.
Common Operations:
• Drilling, Tapping
• Boring, Facing
• Reaming, Thread milling
• CNC profiling (5-axis)
Controls:
• Use of clamping fixtures to avoid distortion
• Coolant type compatible with aluminium
• Machining after stress relief (if applicable)
Quality Methods:
• CMM inspection
• Runout, flatness, perpendicular checks
• GO/NO-GO gauges for threads
Complex parts may need pre-machining before final heat treatment and finishing.

7.5 Cleaning and Packaging Process

Purpose: Remove oils, chips, lubricants; prepare for final delivery or coating.

Cleaning Methods:

Type Description Usage

Aqueous cleaning Hot water + detergent General degreasing
Ultrasonic cleaning High-frequency waves in fluid Intricate geometries
Solvent degreasing Volatile organic solvents Very oily parts
Vacuum degreasing Closed-loop system High cleanliness standard (automotive, aerospace)

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 Packaging Best Practices:
• Avoid corrosion by using VCI bags or desiccants
• Use dividers for sharp/critical surfaces
• Clean gloves during packing to avoid oil marks
Optionally, perform cleanliness testing (e.g., gravimetric or particle count)

7.6 Corrosion Protection (If Applicable)

Aluminium alloys have natural oxide resistance, but further protection may be needed for:
• Marine, automotive, outdoor applications
• Painted, anodized, or powder-coated parts

Types of Coatings:

Coating Purpose Notes

Chromate Conversion (Alodine) Corrosion protection, primer base RoHS-compliant variants exist
Anodizing Build oxide layer Decorative, limited use on HPDC due to porosity
Powder Coating Thick, durable finish Requires clean/degreased surface
E-coating (KTL) Immersion + electrical deposition Great for internal coverage

Controls:
• Thickness measurement (µm)
• Adhesion testing (cross-hatch)
• Salt spray testing (ASTM B117)

Post-Processing Summary Table:

Process Step Key Controls

Trimming Die alignment, flash residuals
Surface Finishing Media type, Ra value, uniformity
Heat Treatment Furnace profile, temp logs, coupon testing
Machining Fixture setup, CMM inspection, burr control
Cleaning Method match to part complexity, no residue
Packaging Dry, corrosion-safe, scratch prevention
Corrosion Protection Coating uniformity, thickness, adhesion

Visual Workflow Example

[Casting] → [Trimming] → [Blasting] → [Machining] → [Cleaning] → [Coating] → [Inspection] → [Packing]

8. Traceability & Documentation in Aluminum Die Casting

8.1 Lot Traceability from Raw Material to Final Product

Goal: Be able to trace every casting back to:
• The alloy batch
• The melting process
• The machine and die used
• The production date/time
• The operator (optional in advanced systems)
How It’s Done:
• Assign a Lot ID for each casting batch (usually per shift, furnace charge, or 500–1000 pcs)
• Track all inputs and process conditions under this Lot ID:
o Raw material certificates
o Furnace used
o Casting parameters
o Post-process steps (machining, coating, etc.)
• Stamp or mark Lot ID on part or label
Tools:
• Barcode or QR code tracking
• MES (Manufacturing Execution System)
• Manual lot cards (in low-volume production)
Checkpoints:
• Lot numbers present on packaging or parts?
• Traceable back to raw material certificates?
• Is electronic or paper tracking system reliable?

8.2 Tool Life Monitoring and Documentation

Goal: Ensure casting tools are replaced or maintained before failures occur (preventing quality defects or catastrophic tool damage).
What’s Tracked:
• Shot count per cavity
• Maintenance cycles (e.g. lubrication, cleaning, insert replacement)
• Tool inspections (thermal cracking, erosion, flash generation)
Tools:
• Shot counters (mechanical or digital)
• Tool tracking sheets
• QR-coded tool IDs with inspection history

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 Metrics:
• Insert life (e.g. 30,000 shots)
• Core pin life (e.g. 15,000 shots)
• Trim die life
Checkpoints:
• Is there a preventive maintenance plan per die?
• Are tool wear records reviewed periodically?
• Are spare inserts available and tracked?

8.3 Parameter History for Critical Parts

Goal: Keep records of machine process parameters for critical or customer-controlled parts (for traceability, troubleshooting, or audits).
Parameters Tracked:
• Furnace melt temp
• Die temp
• Slow shot and fast shot speeds
• Intensification pressure
• Switch-over position
• Cooling flow rates
• Spray cycle and dry time
How It’s Done:
• Use machine PLC or SCADA system to log parameter data
• Attach parameters to Lot ID or Part ID
• Store data in:
o SQL database (automated)
o Excel sheets (manual)
o MES system
Advanced setups can trigger alerts if parameters drift beyond spec.
Checkpoints:
• Can process data be retrieved for past lots?
• Are alarms/events documented?
• Is parameter stability reviewed with SPC?

8.4 Retained Sample Archive

Goal: Maintain physical samples for each production lot to:
• Verify material properties
• Investigate future complaints or failures
• Support PPAP or customer audits
Types of Samples:
• Full castings (non-machined)
• Tensile bars
• Machined sections
• Microstructure samples (embedded in resin)
Storage Guidelines:
• Labelled with Lot ID and date
• Stored in clean, dry area
• Keep for defined period (e.g. 6–24 months depending on customer)
Checkpoints:
• Are samples labelled and catalogued?
• Retention period clearly defined?
• Environmental control (no corrosion or damage)?

8.5 Calibration Records for Measuring Devices

Goal: Ensure all gauges, instruments, and testing equipment are accurate, traceable to standards, and recalibrated regularly.

Examples:

Equipment Calibrated By Frequency

Micrometers, calipers Internal or external lab 6–12 months
CMM Certified service provider Yearly
Hardness tester Accredited lab Yearly
Scales, balances Metrology department Quarterly–Yearly
X-ray equipment OEM or lab As per risk and usage

Records Should Include:

• Calibration date
• Next due date
• Certificate number
• Calibration method & standard used (e.g., ISO 17025)
Checkpoints:
• All devices labelled with calibration stickers?
• Calibration status recorded digitally or on paper?
• Out-of-tolerance instruments quarantined

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 Summary Table – Traceability & Documentation

Item What to Check Tools/Formats

Lot traceability Lot # on part/package, traceable backwards ERP/MES, barcode, manual log
Tool life records Shot count, PM intervals, insert history Die logbook, SCADA, QR system
Process parameter history Full record of critical casting parameters PLC/SCADA data logs
Sample retention Physical samples by Lot #, labeled & stored Sample archive room/logsheet
Calibration certificates Up-to-date, labeled instruments Certificates, master list

Bonus Tip: Build a Traceability Chain

Example structure for a critical casting:
Casting Serial # = B2391-A47

→ Melt Batch = AL-226D/23-04-2025

→ Furnace ID = MF-2A
→ Die ID = DC-M1-B
→ Shot Count = 14,530
→ Parameters = Shot Speed: 4.8 m/s, Pressure: 950 bar
→ FAI Report ID = FAI-2391
→ Tensile Bar ID = TB-2391-2
→ Final Inspector = S. Jovanović

9. Workforce & Safety in HPDC

9.1 Operator Training Program and Records

Goal: Ensure every operator knows:
• The function of the machine
• The safety protocols
• The production process and quality checks

Training Program Content:

Topic Description
Machine operation Shot setup, injection control, alarms
Die setup and maintenance Spray pattern, thermal balance, tool clamping
Defect recognition Cold shut, porosity, soldering, flash
Safety protocols Molten metal handling, emergency stop
Quality control steps FAI, sampling, SPC logging
Maintenance & cleaning Preventive actions, furnace skimming

Best Practices:
• Structured training matrix by role (Operator, Setup Tech, Maintenance, Quality)
• Pass/fail criteria (e.g. test, observed evaluation)
• Periodic requalification (every 6–12 months)
• Onboarding for new processes/tools
Checkpoints:
• Is there a documented training plan?
• Are records kept by employee and module?
• Are operators certified per machine/role?

9.2 PPE Use and Safety Procedures

PPE in HPDC is non-negotiable:

PPE Item Purpose

Face shield Protect against molten metal splash
Heat-resistant gloves For ladling, skimming, tool changes
Aluminized apron/jacket Reflects radiant heat
Safety boots (EN ISO 20349) Molten metal splash protection
Respirator (optional) For fumes/dust from fluxes, sand
Ear protection Machines and shot impact are loud

Molten aluminum at 660 °C can penetrate standard clothing — proper PPE is essential.
Safety Protocols:
• Clear floor demarcation (safe zones vs machine zones)
• Fire extinguishers rated for Class D (metal fires)
• Emergency shower and eyewash stations near furnace area
• Lockout-tagout (LOTO) system during maintenance
Checkpoints:
• Are PPE items issued and replaced periodically?
• Are visual safety instructions posted?
• Are operators wearing PPE at all times?

9.3 5S and Cleanliness in Casting and Machining Areas

5S = Sort, Set in order, Shine, Standardize, Sustain
Importance in HPDC:
• Reduces accident risks
• Increases machine uptime
• Improves workflow efficiency
• Prevents cross-contamination of molten metal and debris

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 Implementation Examples:
• Tools stored at point-of-use in shadow boards
• Mold sprays and lubricants labelled and stored properly
• Casting bins color-coded by lot or shift
• Slag/dross containers properly labelled and isolated
Audit Checks:
• Is the floor free of oil, dross, or scrap?
• Are waste and consumables segregated?
• Are cleaning schedules posted and followed?
• Is visual management (labels, zones) applied?

9.4 Fire Safety Near Melting and Die Casting Area

Aluminium melt is flammable under certain conditions — safety is engineering + procedural.
Fire Risk Factors:
• Water contact with molten aluminium (creates steam explosion)
• Oil/grease ignited by radiant heat
• Electrical arcs from faulty machines
• Dross piles that can self-ignite
Best Practices:
• Class D fire extinguishers (for metal fires)
• No water-based extinguishers near melt zone
• Fire-resistant walls or barriers between melt and casting zones
• Routine inspection of:
o Furnace insulation
o Burners/heating coils
o Gas lines and valves
Response Preparedness:
• Are emergency exits unobstructed?
• Do operators know how to use Class D extinguishers?
• Are fire drills performed quarterly?
• Are melt overflow procedures documented?

Summary Table – Workforce & Safety:

Point Key Controls / Indicators

Operator training Training matrix, certification logs
PPE use Availability, compliance checks
5S in production areas Visual order, labeled tools/materials
Fire safety in melt areas Class D extinguishers, no water-based suppression
Safety signage Clear, multilingual (if needed)
Emergency protocols LOTO, evacuation, eyewash/fire response
Near-miss reporting system Exists, anonymous optional

Workforce Safety KPI Examples (Optional):

KPI Target
Training compliance rate ≥95%
Safety audit compliance ≥90%
Lost Time Incident Rate (LTIR) <1 per 200,000 hours
PPE compliance observations 100%

10. Additional Notes + Pro Tips

This section is used for real-time observations, informal checks, and investigative follow-up that may not fit into formal checklist items.

10.1 Ask for Current Rejection / Scrap Rate and Top 3 Causes
Why It Matters:
Scrap rate gives a snapshot of process health. Top defects often reflect systemic issues in:
• Die design
• Injection parameters
• Operator discipline
• Furnace handling
Good Questions to Ask:
• What is your average rejection rate (%) over the past 3 months?
• Are you tracking rejection per cavity / machine / shift?
• What are your top 3 recurring defects (e.g., porosity, misrun, flash)?
• How do you define and record a “suspect” part?
Benchmark: Good die casting operations typically target <3–5% total scrap. Excellent suppliers may be below 1%.
Pro Tip:
Ask to see rejected parts physically and compare with process settings and tool condition.

10.2 Ask How They Manage Tool Wear and Refurb Cycles
Why It Matters:
Even a well-designed tool will fail if not maintained properly. Uncontrolled tool wear leads to:
• Dimensional drift
• Increased flash
• Cooling imbalances
• Ejection problems

17
 Ask:
• What is your shot counter system for each die?
• How do you decide when to replace cores, pins, inserts?
• Do you perform tool audits (microscopic or dye penetrant inspection)?
• Is preventive mould maintenance tracked digitally?
Pro Tip:
Check how many cavities are actively producing good parts and how many are shut off. This reveals maintenance consistency.

10.3 Ask for Samples from Different Cavity Locations (for Multi-Cavity Dies)
Why It Matters:
In a multi-cavity die (e.g., 2x, 4x, 6x parts per shot), not all cavities perform equally. Common causes of variation:
• Uneven metal flow
• Temperature imbalance
• Air entrapment in farthest cavities
Ask:
• Can I get parts from each cavity separately, not bulk mixed?
• Are cavities numbered or traceable on the part?
• Are there SPC records by cavity?
Sample analysis cavity-by-cavity is especially important when auditing new molds or when one cavity shows abnormal
rejection.

10.4 Take Photos of Critical Points (With Permission)

Why It Matters:
Photos help:
• Explain findings to your internal team
• Document tooling/machine layout
• Track potential hazards or bad practices
What to Capture:
• Parting lines (flash evidence)
• Die lube spraying (distance, pattern)
• Furnace cleanliness
• Trim die condition
• Rejected part storage
• Parameter screen at time of casting
• Mold identification and serial number
Always ask permission first — and note if the supplier is hesitant or evasive.

Pro Tips from Field Experts

1. Carry a Surface Roughness Comparator

Compare casting surface finish vs. standard tactile samples (e.g., Ra 3.2 / Ra 6.3). This helps confirm claims about shot blasting
or tool polish.

2. Use Infrared Thermometer or Thermal Camera

Spot-check mould temperature or surface temp of castings. Large variation may reveal cooling circuit issues or poor preheating.

3. Ask for SPC Charts or Raw Data

If supplier says, “we do SPC”, ask:
• Which characteristics are tracked?
• Can you show live or recent charts?
• What is the current Cp/Cpk value?

4. Watch One Full Cycle at the Machine

Stand and observe:
• Furnace → ladling → spraying → injection → ejection → trimming
• Note inconsistencies in timing, hesitation, or operator intervention
• Time the full cycle with stopwatch (cycle time)

5. Look at the Operator Instructions Posted

Ask:
• Are visual work instructions available at the station?
• Are control limits or reference parts visible?
• Are instructions in language operators understand?

6. Ask How They Handle Regrind or Scrap Returns

For cast-on-overflow processes, ask:
• Do you remelt all sprues/gates?
• How many re-melt cycles do you allow?
• Is scrap mixed with primary alloy or segregated?
Overused scrap may introduce oxides and inclusions, degrading casting integrity.

7. Ask How They Perform Tool Trials or Engineering Changes

A robust supplier should:
• Document tool trials and changes
• Use trial reports with measured data
• Involve customer in pre-approval of modifications

18
 Final Additional Checklist Summary:

Process Step Key Questions / Actions

Scrap Rate What is current % and trend? What are top 3 defects?
Tool Wear Are insert lives tracked? PM intervals?
Cavity Sampling Can you provide per-cavity parts and SPC?
Photo Documentation Take pictures with permission
SPC Charts Can they show current control charts?
Process Observation Watch full cycle, note weak points
Surface Finish Check Compare with Ra standard or spec
Infrared Checks Die/casting temperature balance
Regrind Use What % is used? Monitored? Cleaned?

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