Original Date: 05/01/2000
Revision Date: 01/18/2007

Magnetics are transformer-type devices that have the primary function of regulating voltages in an electronic device. Northrop Grumman Defensive Systems Division (DSD) has over three decades of experience in designing and manufacturing magnetic components. Approximately 372 magnetic types have been produced on 21 programs, varying from a one-gram air coil to a 27-pound step-up transformer. All magnetics are built to meet the requirements of MIL-T-27. Past practices at Northrop Grumman DSD dictated that all magnetics be 100% tested by Quality Assurance (QA). Surface preparation, if required, was performed on a one-by-one basis using labor intensive and inconsistent grit blasting. The materials used were not robust, and therefore unrepairable if defective. The use of carriers to facilitate the ease of assembly was also non-existent. To resolve these issues, Northrop Grumman DSD underwent a fundamental paradigm shift in its practices.

Northrop Grumman DSD provides the necessary training and tools to its production operators, empowering them to perform in-process inspections on 98% of all magnetic product types. QA inspects the remaining 2%. Where possible, carriers have been added to the product designs to assist in assembly. Other improvements include replacing grit blasting with plasma etching of components to improve adhesion; using robust materials to allow repair/rework of some defective products; and performing surface preparation on a lot basis. Process controls established include Design of Experiment, Design for Manufacturability, and Statistical Process Control (SPC) for critical design parameters (e.g., wire tensile strength, cleanliness). Design for Manufacturability is instituted by Operations on all new product types, enabling Northrop Grumman DSD to continue producing quality magnetic components efficiently.

As a result of these improvements, Northrop Grumman DSD instituted a findings feedback loop via e-mail to Design Engineering. These findings are used to refine future designs and avoid past problems. With design directions evolving toward smaller packaging, increased power, less environmental sensitivity, and simpler assembly at 98%+ yields, Northrop Grumman DSD’s initiatives position the company to continuously improve the quality, reliability, and cost of its magnetic components.

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