TECHNOLOGY AREAS: Materials/Processes, Sensors, Weapons

ACQUISITION PROGRAM: PMA-242, Advanced Anti-Radiation Guided Missile (AARGM), ACAT-1

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 3.5.b.(7) of the solicitation.

OBJECTIVE: Develop tooling and machining applications for ceramic radomes that reduce set-up time and dimensional mismatch. This has the benefit of having a more producible ceramic radome for radar applications and more repeatable radio frequency (RF) performance.

DESCRIPTION: The RF performance of a MilliMeter Wave (MMW) missile is highly dependent on the dimensional tolerances of a ceramic radome. Small deviations and variances of extremely tight tolerances on both the inner and outer contours of the radome will impact the insertion loss of the RF performance of the radome and thus will impact the radar performance of the MMW missile. The current method for machining radomes utilizes a combination of custom made and commercial water-cooled diamond grinding tools on a Computer Numerically Controlled (CNC) machine center. The process requires multiple iterations with multiple machine setups for both inner and outer contour machining. Additionally, repetitive dimensional inspections are required to ensure a tightly controlled finished radome wall thickness. The current process is essentially the same approach that has been used for over 20 years on pyroceram radomes. In many cases it is so difficult to re-align the radome properly back onto the machine that the radome has to be scrapped as its dimensional deviation makes the radome unusable for radar performance. This results in high production costs and inhibits RF performance.

The goal of this innovation is to apply improved tooling and manufacturing techniques to the development of a ceramic machining process to control a radome wall thickness and concentricity to less than .001". With the development of an improved tooling and manufacturing technique, it is the objective to achieve the ability to machine the inner contour and outer contour of the ceramic radome in a two step process. One set up and machining step each for the inner and outer contour machining; allowing the radome to remain in place while all machining is accomplished. Recent data from researchers show the insertion loss values of properly manufactured radomes is about 1.5dB, In comparison, the conventional machining techniques have produced radomes with an insertion loss of 2.5 dB (at W band), are more time consuming and result in higher costs and lower yield. The new machining technique has the promise to better meet RF performance, reduce production time, and reduce manufacturing costs.

PHASE I: Design and develop an innovative method of tooling and machining for ceramic radomes. Evaluate the improved dimensional control of machining both the inner and outer contours using a reduced number of setups. Develop a machining process definition that will include equipment descriptions, tooling and support fixture concepts, and projected time and labor utilization for the recommended processes. Emphasis should be on determining the RF insertion loss performance of the newly machined ceramic radomes to satisfy missile RF MMW insertion loss requirements. Perform validation to include RF measurements on machined radomes for comparison with the baseline process. Investigate a notional machining approach to machine inner and outer radome contours using the same tools and fixtures.

PHASE II: Construct and demonstrate the operation of the prototype tooling to machine the inner and outer contours of ceramic radomes in a very low rate production setting. Define test objectives and conduct limited testing of a minimum of ten (10) radomes over a six month period. Each successfully tooled radome should be tested for RF insertion loss at W band to measure if it is within acceptable standards.

PHASE III: Finalize and fabricate tooling to prepare for production run. Successful manufacturing of the tooling and technique, may result in the ability to fabricate 300-400 ceramic radomes per year.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Any application that requires high precision machining of ceramic (aircraft avionics, missiles) could benefit from success of this technology. The use of ceramics has advantages over metal depending upon the application. Ceramics are harder and stronger in compression than most metals. In addition, ceramics can be electrically or thermally insulating or conducting.

REFERENCES:
1. Ceramic Machining Evaluation, Technical Report, NCDMM Project No. NQ04-0001-02 Redstone.

2. Sheppard L. M., "Green Machining: Tools and Considerations for Machining Unfired Ceramic Parts" Green Machining, Article, ISSN: 0009-0220, 1999, Vol. 149, No. 6 Pg. 65.

KEYWORDS: machining; ceramic; radomes; high precision; ceramic machining; milli-meter wave

TPOC: (301)757-7383
2nd TPOC: (301)757-7382

** TOPIC AUTHOR (TPOC) **

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