Green Body Machining of Domes

Applications, such as the JCM and Small Diameter Bomb, require affordable, durable domes with multiple-waveband transparency (i.e., near-IR, MWIR, LWIR and MMW). Cost effective fabrication of such domes, will require achieving the optimal balance between competing requirements. Choice of durable dome materials, with suitable transparency, high speed/tight tolerance fabrication techniques, and incorporation of suitable grid/resonant structures to provide EMI shielding and suitable MMW transmission are critical to the development of tri-mode seeker dome designs. In this program, Surmet proposes to utilize the standard CIP process and mold designs to perform initial testing to define green machining process parameters and define low contamination tooling materials for green machining ALON™ and spinel missile domes. Binder systems will be evaluated and cutting parameter such as feed rate, spindle speed, tool cutter material, shape and angle must be optimized to cleanly machine the hard abrasive ALON and spinel with minimal contamination and subsurface damage. An assessment of the tolerance limits of the green machining process on the green machined part and the resulting fired dome shell will be made. Methods to assess residual damage and gross defects will be examined. Feasibility to reuse swarf powder from the green machined dome will be examined.