Product Inspection Process for Aluminum Cylinder Heads

High-Quality Assurance from Raw Material to Final Packaging

1. Incoming Material Inspection

Aluminum Alloy Composition Analysis

• Use spectrometers to analyze the aluminum alloy grade (e.g., A356.2, AC4B)

• Check material certificates and traceability of furnace batch numbers

Auxiliary Material Inspection

• Check batch numbers, appearance, drying quality, and flowability of coatings, sand cores, and chills

2. Post-Casting Inspection

Visual Inspection

• Check for porosity, slag inclusion, cracks, deformation, and cold shuts

• Verify the profile and dimensional completeness according to drawings

X-ray Defect Testing

• Conduct non-destructive testing (NDT) on critical areas like combustion chambers, water, and oil passages

• Evaluate internal defects such as shrinkage cavities, sand holes, and inclusions

3. Post-Machining Inspection

Dimensional Inspection

• Use CMM, calipers, and micrometers to check critical dimensions

• Inspect valve guide holes, valve seat bores, camshaft journals, and head flatness

Thread Hole Inspection

• Check threads with go/no-go gauges

• Ensure concentricity and thread integrity

Hardness Test

• Perform Brinell or Rockwell hardness testing to confirm heat treatment or natural aging results

4. Leakage & Pressure Test

Water Jacket Air Pressure Test

• Inject 0.5-1.0MPa of air pressure, hold for 1 minute, and check for leaks or bubbles

Oil Passage Pressure Test

• Simulate oil pathways using fixtures, then conduct pressure holding and sealing tests

5. Final Appearance & Cleanliness Inspection

Cleanliness Check

• Inspect for residual metal chips or sand inside the casting

• Use endoscopes or cleanliness analysis devices to detect contamination

Surface Treatment Confirmation

• Verify deburring, sandblasting, passivation, and coating quality

• Check if labeling, batch number, and anti-rust protection are in place

6. Final Pre-Packaging Inspection

• Inspect product model, batch number, and accessory completeness as per shipping standards

• Verify traceability via QR codes, laser marking, or serial numbers

• Ensure packaging materials are clean, pressure-resistant, and moisture-proof

• Include certificates of conformity and packing list before shipment

Remarks

• One sample from each batch should be retained for traceability

• Inspection records must be archived for no less than three years

• Custom test plans available upon client request

Product assembly testing and road testing

1. Cylinder Head Assembly Testing Procedure

Pre-Inspection of Components

• Inspect valves, valve guides, valve seats, springs, oil seals, camshaft, and bushings

• Confirm material certificates and hardness test reports

• Ensure dimensional accuracy per technical drawings

Precision Assembly

• Install valve group （valve, spring, retainer, locks）

• Press-fit valve stem seals carefully to avoid damage

• Insert valve guides and check clearance （g.， 0.02-0.05 mm）

• Perform valve sealing test （g.， kerosene leak test or vacuum test）

• Assemble camshaft and bearing caps, tighten bolts per torque and sequence specs

• Adjust valve clearance if applicable

Dynamic Function Test

• Rotate camshaft manually to ensure smooth movement

• Check valve timing and spring return

• Perform pressure testing：

• Air pressure test

• Oil passage pressure test

• Run vacuum or pressure leak test on assembled head

2. Cylinder Head Road Test Procedure (for Aftermarket Units)

Trial Installation & Cold Start Check

• Install cylinder head assembly on engine using OEM torque sequence and specifications

• Fill coolant and engine oil

• Start engine cold, observe for eaks, abnormal noise, and idle stability

Warm-Up Test （Idle and Load）

• Bring engine to operating temperature （ 90-95°C）

• Test under idle and increased RPMs

• Monitor：

• Valve noise

• Valve clearance behavior

• Oil pressure and coolant temperature

• If no anomales after 20-30 minutes, proceed to road test

Road Simulation Test

Recommended Duration: 500-3,000 km （depending on project scope）

• Driving Conditions：

• Urban driving: Stop-and-go traffic, idle time

• Highway driving: Constant speed at higher RPM

• Uphill/High-load segments: Test combustion chamber temperature resilience

• Rapid acceleration/deceleration: Test oil supply, valve spring response

• Monitoring Points：

• Coolant and oil levels

• Smoke emissions （white = coolant, black = fuel, blue = oil）

• Unusual engine sounds

• Overheating or temperature spikes

• Check engine lights or OBD readings

Post-Test Disassembly & Analysis

• Remove the cylinder head and inspect：

• Valve and seat condition （burning, deformation）

• Valve guide wear

• Gasket impressions and sealing effectiveness

• Flatness of the head base

• Any signs of cracks, corrosion, or oil/water leakage

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