+86-13516964051 
News
Aluminum alloy low
0102030405
Top Bulk Procurement Tips for Airport Automation Equipment
2026-07-23
Airport automation equipment encompasses self‑check‑in conveyor rollers, baggage sorting trolley frames, boarding bridge drive housings, security conveyor motor mounts, automatic door slide rail supports, and more. These components are not aviation safety‑critical parts but high‑availability public infrastructure elements—operating over 18 hours daily with narrow maintenance windows and downtime costs calculated by the minute. Thus, buyers’ core demands for aluminum‑Zinc Alloy Die Castings, gravity castings, and low‑pressure cast structural parts are not “low cost” but batch‑to‑batch consistency, dimensionally fit‑for‑assembly without adjustment, and surface weather resistance for 10 years without chalking. From a global buyer’s perspective, this article outlines verifiable, contract‑writable tips for bulk procurement of airport automation equipment castings, focusing solely on specifications and evidence rather than origin.
First, Lock in Process Division: Die Casting, Gravity Casting, and Low‑Pressure Casting Are Not Interchangeable
Airport automation equipment castings are categorized into three types by load‑bearing and airtightness requirements, which must be listed separately in procurement documents:
High‑Pressure Die Casting (HPDC) Aluminum Castings
Suitable for thin‑walled housings, motor end covers, sensor brackets, and non‑load‑bearing large panels. Common alloys include A380 (ASTM B85), ADC12 (JIS H5302 equivalent to A383), and A360. Advantages: fast cycle times, stable dimensions (linear tolerance within 50mm is approximately ±0.13mm under NADCA standards). Disadvantages: internal gas entrapment; not suitable for conventional T6 Heat Treatment or welding.
Permanent Mold Gravity Casting
Ideal for medium‑load supports, roller side plates, and load‑bearing parts requiring post‑heat treatment. Common alloys: ZL101A (ZAlSi7MgA) and A356 series, which can undergo T6 solution aging. Internal density is superior to die casting, but cycle times are slower and unit costs higher.
Low‑Pressure Casting
For housings with high airtightness and fatigue strength requirements, such as sorting trolley hub bodies and cylinder mounts. Density falls between die casting and gravity casting, with long mold life.
If procurement documents only state “aluminum alloy castings,” suppliers may quote gravity cast parts with die cast alternatives, leading to early cracking of load‑bearing components after installation. The correct approach is to specify processes by part function: HPDC allowed for non‑load‑bearing thin‑walled parts; permanent mold gravity or low‑pressure casting with T6 specified for load‑bearing parts.
Material Certificates Must Include Heat Numbers, Not Just Grade Declarations
Airport project owners often audit back to melting furnace batches. Bulk procurement contracts should require:
- Each batch includes a Mill Test Report (MTR) with measured spectral composition values, verifying alloy grade compliance against ASTM B85, DIN EN 1706, or ISO 3522—not just “ADC12 meets standards.”
- Gravity‑cast A356 T6 parts must include mechanical properties from same‑furnace test bars: tensile strength, yield strength, elongation, Brinell hardness, plus heat treatment furnace batch numbers and curve summaries.
- Zinc alloy die castings (Zamak 3 / 5) for indoor touch brackets must comply with ASTM B86, with strict control of lead and cadmium content to meet RoHS (Pb < 1000 ppm, Cd < 100 ppm) and REACH. Factories providing only a “material guarantee” without heat numbers or spectral data are unfit for airport‑grade supply.
Dimensional and Geometric Tolerances: Write GD&T into Procurement Specifications
Airport automation equipment involves multi‑axis assembly with sensitive cumulative errors. Procurement specifications should directly reference:
- Die casting dimensional tolerance grades CT6 to CT7 (per GB/T 6414 or ISO 8062), with 0.5–1.5mm machining allowances on machined surfaces.
- Position tolerance of ±0.05mm for critical mounting holes, verified via full‑size CMM reports—not caliper spot checks.
- Flatness per NADCA recommendations: ≤0.15mm per 25mm.
- First articles require PPAP Level 3 submission (including PSW, control plan, PFMEA, full‑size CMM report, material report, and process capability Cpk ≥ 1.67). Subsequent batches include factory CMM key characteristic inspection sheets. Procurement without GD&T drawings and only “per sample” specifications will inevitably lead to assembly interference in the third container.
Internal Quality: X‑Ray Rating and Airtightness Thresholds
Baggage sorting and boarding bridge drive components often include oil or air passages, where internal shrinkage porosity is a hidden failure point. Procurement tips:
- Contracts for load‑bearing and airtight parts specify X‑ray inspection per ASTM E155 or EN 12681, with no level‑2+ pore clusters in critical areas.
- Housing parts undergo 0.3MPa air pressure hold for 30 seconds without leakage (following automotive housing practices).
- Three pieces per batch are reserved for cross‑section metallography to check grain uniformity and iron‑rich phases, preventing brittle fracture from excessive reclaimed material use.
Surface Treatment: Hard Anodizing Film Thickness and Salt Spray Must Be Fixed
Castings in airport arrival halls and outdoor boarding bridge areas face triple erosion from UV radiation, de‑icing salts, and cleaning agents. Procurement specifications recommend:
- Aluminum hard anodizing: 15–25μm film thickness, microhardness ≥ HV350, and qualified sealing per ISO 2931 dye spot testing.
- Neutral salt spray testing per ISO 9227 for 500–1000 hours with no base metal corrosion or white rust.
- Powder coating for non‑anodized outdoor parts: 60–80μm film thickness, cross‑cut adhesion grade 0, and color difference ΔE ≤ 1.5.
- Zinc alloy parts avoid hard anodizing (process incompatible); use plating + passivation or electrophoresis instead. Remove “anodizing” from contracts to avoid errors.
Five Essential Documents for Supplier Due Diligence
Before finalizing bulk orders, request original scans (not screenshots) from candidate factories:
- ISO 9001 certificate and latest external audit report.
- IATF 16949 certificate (non‑mandatory but indicates process control maturity) if automotive‑grade production lines are involved.
- Alloy MTRs and X‑ray films from third‑party labs in the past 12 months.
- CMM full‑size report templates (verify position tolerance measurement capability, not just outer diameter checks).
- PPAP sample document package (confirm genuine APQP implementation, not ad‑hoc assembly). Factories refusing PPAP samples citing “trade secrets” while promising “quality assurance” lack airport project supply eligibility.
Phased Control for Volume Ramp‑Up and Acceptance
A three‑stage procurement rhythm is recommended and written into framework agreements:
- Stage 1: 3–5 mold samples, 100% inspection + X‑ray, signed and sealed samples.
- Stage 2: Small batch of 100–300 pieces, AQL 2.5 sampling, assembly line trial fitting.
- Stage 3: Mass production batches include MTR, CMM key dimensions, and salt spray cycle reports (retained rolling); first‑article inspection mandatory for each mold run. Aluminum die casting yield rates typically exceed 95% (up to 97% for die casting). Contracts may stipulate deductions for below‑threshold yields, but full acceptance via final inspection is not recommended—SPC records of process parameters (mold temperature, injection speed, vacuum) are the basis for early defect prevention.
Bottom‑Line Principles
Airport automation equipment casting procurement essentially translates “public infrastructure availability” into contractually binding figures for materials, tolerances, inspection, and salt spray. Suppliers unable to specify grades as A380 + ASTM B85 + heat‑numbered MTR, tolerances as CT7 + position tolerance ±0.05mm, or surface treatment as 20μm hard anodizing + 500‑hour ISO 9227 salt spray—regardless of catalog thickness—should be excluded from bulk framework agreements.