Leak Testing

Our full cleanroom services include a range of testing, including leak testing, for helium and positive pressure testing. Macfab’s focus on providing a low total cost of ownership through quality work is enabled through our leak testing of prototype and production parts.

Leak testing is a form of Non-Destructive Testing (NDT). This type of testing allows for validation of the part and process, without sacrificing or scrapping the part. Our Agilent vacuum, leak detectors, and innovative custom testing systems will ensure your parts arrive as expected.

Leak Testing in Static and Dynamic Conditions

As a supply chain partner focusing on mutual success, Macfab conducts leak testing on all prototype-type parts that require it. We carefully review our internal process and retest the part if a crack or hole is found. Our engineering team has developed fixturing to allow testing in static (stationary) and dynamic (moving) conditions.

As a part moves into production, so does our leak testing. The focus remains to identify defects that can only be found using this testing method. Our engineering and quality control teams develop sampling plans based on the consistency of the process and experience, conducting periodic inspections of the parts to validate that the process remains in control. A stable process generates a steady flow of products for our customers.

Macfab practices these leak testing methods in order of sensitivity:

Air Pressure (Vacuum) Decay

Air Pressure (Vacuum) Decay utilizes air up to 80 pounds per square inch (PSI) in a vacuum. This process reduces the variation caused by temperature, has a higher throughput than other methods, and can detect multiple defects if present.

Bubble Immersion

The Bubble Immersion method is used to test welds and sealing of assemblies. The test piece can be pressurized at 3 to 40 PSI with a maximum of 125 PSI and submerged in a tank of water. The inspector then looks for bubbles indicating a defect.

Helium Mass Spectrometry

At nearly double the sensitivity of the bubble test method is Helium Mass Spectrometry 100x to 1,000,000x. This method requires developing a negative pressure difference between the test part and the atmosphere. This method can record a quantitative measurement volume of cubic centimetres per second (atm cc/sec) of the leak rate. Depending on the configuration of the part/assembly and the precision with which this testing is done, the location of the leak(s) can often be identified on the part.

The testing methods Macfab performs are highlighted.
Additional information in the table are other testing methods and their comparison for reference.

Method	Quantifiable Result	Locate Leak	Global ¹	Go/ No Go	Test Media	Test Volume Dept.²	Relative Cost
Air Pressure (Vacuum) Decay	Yes	No	Yes	Yes	Air	Yes	Medium
Mass Flow	Yes	No	Yes	Yes	Air	Yes	Medium
Dye Liquid Tracers	No	Yes	No	No	Liquid	No	Low
Bubble Immersion	No	Yes	No	No	Air	No	Low
Thermal Conductivity Sniffing	Limited	Yes	No	Yes³	Helium	No	Low
Sulfur Hexafluoride (SF6) Sniffing	Limited	Yes	No	Yes³	SF₆	No	Low-Med
Helium Mass Spec Sniffing	Limited	Yes	No	Yes³	Helium	No	Med-High
Helium Mass spec Atmosphere Accumulation	Yes	No	Yes	Yes	Helium	Yes	High
Helium Mass Spec Hard Vacuum	Yes	Yes	Yes	Yes	Helium	No	High
Trace Gas Mass Spec Hard Vacuum	Yes	Yes	Yes	Yes	R134_a, SF₆, Air, H₂, NO₂, CO₂	No	High

Clarification Points
1. The test method measures the part’s global leak rate versus individual leaks.
2. The test volume significantly affects the test cycle time and/or sensitivity.
3. Results may vary based on skill of operator.

While no process is error-free, our investment in multiple methods and a range of leak testing sensitivities provides us with options to meet our customers’ expectations from engineering specifications, quality verifications, and supply chain requirements.

Let’s discuss the option best suited for your part and total cost of ownership.