Trust But Verify: Process and Product Validation

By George Allman on 06 February, 2019

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In cable assemblies and wire harnesses, there are hundreds and often thousands of opportunities for defects per assembly. Therefore, it is imperative that a manufacturer takes rigorous steps to mitigate the risk of incurring those defects. Multiple process controls must be deployed to ensure that a wire assembly is produced that meets or exceeds the customer’s requirements. Many of these measures are taken before the components are even built. Revision-controlled quality requirements---specified on prints and in workmanship standards---must be understood. Operators must be trained and must demonstrate this understanding. As an assembly is produced, a predetermined regimen of tests and other validations are employed, both by operators and technicians. These validations, depending on the project, can include mechanical, electrical, and environmental tests. Each of these stages in the quality assurance process ultimately ensures that the product meets or exceeds the customer specifications.

In the beginning stages of the manufacturing process, a first article of the product is created. Mechanical stress in the form of a pull-test is applied to the conductor and crimp combinations of the product. This pull-test ensures that the manufacturer has necessary information to create a finished trust but verify (1)product that will meet the requirements specified in the design. After the pull-test and other preliminary operations are completed and before the next step of assembly begins, the manufacturer adjusts tools and manufacturing methodologies as needed to minimize variation during the manufacturing process.

Once the product is partially and/or fully assembled, additional quality validations can be performed. This can be as simple as visually validating the assembly and recording the results digitally, or conducting fit checks to verify that the product meets specifications. This stage also includes electrical tests in which the required electrical conditions are applied to the necessary elements of the assembly. These tests---which typically include point-to-point continuity, HIPOT or dielectric strength, and insulation resistance---ensure that the interconnects are working and that the assembly performs as intended. The manufacturer can also utilize an RF analyzer, which measures radio frequency signals. This layer of testing is especially important for high definition systems, such as communications systems and aircraft.

After electrical tests are performed, the assembly might endure rounds of environmental tests. An environmental test chamber performs thermal cycle tests on the product, which measures how well the assembly works under the specified temperature ranges. The environmental test chamber can also provide insight on how well the product performs in various humidity conditions. A separate test may be conducted by flexing the product to measure its range of motion. Making sure the assembly performs well under various temperature, humidity, and mobility conditions is an important step in verifying that the product meets the customers’ standards.

When an assembly is being manufactured, it is important to minimize process variation to prevent defects. This is done at every stage of the process, from planning to building to testing to final inspections. Layers of quality checks during the manufacturing process, including mechanical, electrical, and environmental tests, provide validations that ensure the product is being produced to the satisfaction of customer.

Have questions about the details of our quality controls?  Contact us here. 

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Topics: Risk Mitigation, Cable Assemblies, Quality Control, Quality, Materials Performance, Wire Harnesses, Design, Design Challenges, Box Builds

Author: George Allman

George Allman is a Manufacturing Engineering Supervisor that has been with Liberty for 21 years. He works primarily in process and fixture development within Liberty’s Mil/Aero Business unit, and also helps to support new business growth and development in various capacities. He is a member of the Society of Manufacturing Engineers, serves as an advisor/mentor to local STEM student groups, and is a frequent speaker and contributor at various events within the Additive Manufacturing community.
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About Wired Success 

Wired Success is a Liberty Electronics publication for engineers, procurement professionals, and others in manufacturing and the supply chain who want to keep up with news, advances, and products for use in a range of industry sectors to include aerospace, defense contracting, rail, light transit, medical devices, and more. Please subscribe for regular updates or follow us on our social media channels. For media inquiries, please contact us here.


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