By Justin Sheard, Fluke Acoustic Imaging Expert
In the competitive world of white goods manufacturing, ensuring product quality and reliability is vital to reducing warranty claims, avoiding costly recalls, and safeguarding brand integrity. From washing machines and dishwashers to refrigerators and heat pump dryers, these household appliances must be thoroughly tested for leak tightness and structural integrity during in-line and end-of-line (EOL) production processes.
In white goods manufacturing, washing machines like these must retain water under dynamic conditions.
Historically, leak detection has relied on water baths, pressure decay, and manual inspections. While effective, these methods can be time-consuming, imprecise, or difficult to automate. The integration of ultrasound imaging technology, such as the Fluke SB140 Sound Beacon combined with the Fluke ii905 or ii915 Acoustic Imager, is redefining leak detection in the white goods industry by enabling fast, repeatable, and non-invasive testing on high-speed production lines.
The Need for Leak and Tightness Testing in White Goods
Modern white goods are complex appliances with multiple fluid, air, and sealed compartments:
- Washing machines and dishwashers must retain water under dynamic conditions.
- Refrigerators and freezers rely on hermetically sealed refrigerant loops and air-tight doors.
- Dryers and air-pump systems must maintain airflow and insulation integrity.
Leaks in any of these systems can lead to safety hazards, customer complaints, energy inefficiency, or regulatory non-compliance. Tightness testing must therefore be thorough, fast, and precise—especially in high-throughput environments where hundreds or thousands of units are produced daily.
Common Leak Testing Challenges in White Goods Manufacturing
Traditional methods have notable limitations:
- Water bath tests require pressurization and manual visual inspection for bubbles.
- Pressure decay tests can indicate a leak but do not localize it.
- Soap bubble tests are low-cost but labor-intensive and imprecise.
- Helium leak testing is extremely sensitive but expensive, slow, and not always scalable.
What manufacturers need is a solution that provides real-time leak localization, fits into automated or semi-automated stations, and requires minimal setup and training.
Fluke ii905 Acoustic Imager and Fluke SB140 Sound Beacon
Ultrasound Imaging as a Solution
Ultrasound leak detection works by identifying high-frequency sound waves generated by air escaping through small gaps or seal failures. The Fluke SB140 Sound Beacon emits a controlled 40 kHz ultrasonic signal. When placed inside a compartment—such as a refrigerator chamber, washing machine tub, or dishwasher enclosure—this signal escapes through any weak points.
Operators use the Fluke ii905 or ii915 Acoustic Imager to scan the exterior. The imager, operating in "Beacon Mode," isolates the 40 kHz frequency and displays visual feedback of where the sound escapes. This allows immediate and precise identification of leak locations.
Application Areas
Washing Machines and Dishwashers
- Inspect door gaskets, drum welds, and sump assemblies for seal integrity.
- Scan around detergent compartments and water inlet valves.
- Identify weld or assembly flaws in tub seams that would otherwise require submersion testing.
Refrigerators and Freezers
- Verify door seal compression and cabinet gasket tightness.
- Detect air leaks at vacuum insulation panels (VIPs), ice maker housings, and air ducts.
- Use in place of pressure tests that may be impractical for low-pressure compartments.
Heat Pump Dryers and HVAC Systems
- Test blower seals, airflow channels, and drain systems.
- Identify early-stage assembly flaws or compression issues in evaporator or condenser housings.
Comparison with Traditional Methods
| Testing Method | Pressurization Required | Leak Localization | Cycle Time | Sensitivity | Integration Complexity |
|---|---|---|---|---|---|
| Water Bath | Yes | Visual (bubbles) | Slow | Medium | High |
| Pressure Decay | Yes | No | Medium | Medium | Medium |
| Helium Leak Detection | Yes | Indirect | Slow | Very High | High |
| Manual Bubble Testing | Yes | Visual | Very Slow | Low | Low |
| Ultrasound Imaging (SB140) | No | Direct/Visual w/ On-Screen Image | Fast | High | Low |
Ultrasound imaging offers a unique combination of speed, visual clarity, and low disruption, making it ideal for both in-line quality checks and spot testing in response to anomalies.
Regulatory and Quality Standards
White goods manufacturers operate under a global patchwork of safety and quality regulations:
- IEC/UL 60335-2: Safety standards for household electrical appliances (global/U.S./Canada).
- ISO 9001 and ISO 14001: Quality and environmental management systems.
- IATF 16949: Applies to appliance makers supplying automotive or industrial HVAC systems.
- EPA Section 608 (U.S.) and F-Gas Regulation (EU): Regulate handling and detection of refrigerants, especially R600a and R290.
Leak detection systems must support compliance with these standards, offering traceability and documentation. Acoustic imagers allow operators to capture visual evidence of inspection results for inclusion in quality control logs and digital manufacturing records.
Use Case: EOL Leak Testing in a Refrigerator Manufacturing Line
A European appliance manufacturer producing over 10,000 refrigerators per day sought a more efficient way to confirm door seal integrity and compartment tightness. Traditional pressure-based methods delayed line speed and required manual interpretation.
With the Fluke SB140 Sound Beacon placed inside the refrigerator compartment and a Fluke ii905 Acoustic Imager at the test station, inspectors could visually scan door seals and vacuum panel joints within 30 seconds per unit. Any leaks were immediately flagged, corrected, and documented, improving first-pass yield and reducing rework rates.
The system required minimal training and was deployed at multiple stages of the line, allowing both random sampling and 100% inspection, depending on the model.
Benefits of Ultrasound Leak Detection in White Goods Production
- Non-Invasive: No fluids or pressure needed
- Fast: Supports high-throughput lines
- Precise: Pinpoints the exact leak location
- Documentable: Visual output for audits and traceability
- Operator-Friendly: Requires minimal training and oversight
- Adaptable: Works across appliance types and manufacturing geographies
Conclusion
In a market where speed, quality, and compliance are non-negotiable, ultrasound imaging offers a next-generation approach to leak and tightness testing in white goods manufacturing. The Fluke SB140 Sound Beacon and compatible acoustic imagers provide a fast, accurate, and scalable method for identifying leaks across various appliances.
By replacing traditional, manual, or destructive leak tests with real-time visual ultrasound detection, manufacturers can streamline production, improve quality assurance, and meet international safety and environmental standards with confidence. As industry demands increase, acoustic imaging positions itself as a strategic asset in the pursuit of lean, reliable, and regulatory-compliant appliance manufacturing.
About the Author
Justin Sheard is an accomplished product development leader specializing in thermal and acoustic imaging technology, particularly in preventive maintenance applications. With multiple patents and published works, Justin is a thought leader in the industry. He is dedicated to shaping the future of preventive maintenance through innovative imaging solutions that help maintenance professionals prevent unplanned downtime and improve operational efficiency. Connect with Justin on LinkedIn.