Special Tooling and Processes for Repeatable Adhesive Application

In his proposal, we present the development of an automated dispensing system for the precise, repeatable application of LLCs to a variety of threaded surfaces. The CAPCO SecureThread system will incorporate a microvalve dispenser along with a rotary collet and translating linear stage which will allow for precise (nanoliter scale accuracy), repeatable, and adjustable application of LLCs directly to the thread root. SecureThread features a modular interface for use with a broad range of fasteners and threaded items (e.g. ignitors): with external and internal threads, varying thread pitch and handedness, material, length, diameter, and drive type. Subsequent to the prototype development of the SecureThread system, CAPCO will perform extensive analysis on fasteners, LLCs, and primers of interest to the MDA. LLC application volume and distribution specifications are not well understood, so processing sensitivities, cure times, and the minimum amount of LLC required to achieve optimum breakaway torque values will be investigated. Preliminary work by the proposer suggests that the relative increase in breakaway torque provided by LLCs depends more on the application method than the amount of LLC applied. Optimized LLC and fastener configurations will be vibration tested per MIL-STD-801 to verify LLC performance in MDA configurations of interest. Approved for Public Release | 16-MDA-8917 (15 November 16)