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