Avenger Bustle Box Delamination Reduction

Problem / Objective Letterkenny Army Depot (LEAD), Chambersburg, PA is currently in the process of producing components for the Avenger Bustle Box using a new composite material. This composite material is highly desired due to its superior performance and 45 percent weight reduction in comparison to the current bustle box material. LEAD is currently manufacturing these new composite panels with the use of a waterjet cutting process. The current waterjet cutting process has been identified as the cause of slight delamination of the outer layers of the composite material. This process also causes water damage between the layers by impregnating the composite core with water.The current waterjet cutting process time runs at about 70 inches per minute. Accomplishments / Payoff Process Improvement The NCDMM initiated the development of a solution by having test material, supplied by LEAD, sent to the NCDMM Testing and Development Lab. The NCDMM with the assistance of an Alliance Partner developed several cutting tools for testing. The first phase of testing began by researching various cutting tool geometries. Once the tool geometries were selected, optimal cutting speeds and feeds were determined. Photos of the cutting tools were taken, tool wear was measured, and the data was recorded. All tests were conducted at full depth/full slot. The initial test data results showed that some tools preformed better than others. Therefore, the main focus was redirected to the cutting tool that provided the least amount of delamination to the outer layers of the composite material. After careful evaluation, one tool was selected for additional life testing. In order to enhance the productivity of the selected tool, the NCDMM developed and conducted a Design of Experiments (DOE) to find the optimum run parameters. Upon completion of the DOE, the new tool design was capable of running at 119 inches per minute. The NCDMM then proceeded to investigate the cutting tool life. Follow-up life test results ran at 119 inches per minute and showed significant improvements to the composite quality as well as a reduction in cutting time. This was achieved with minimal wear to the cutting tool. The NCDMM, with the assistance of a key Alliance Partner, was able to develop an advanced cutting tool that would efficiently machine the composite material to the specifications required by LEAD. Implementation and Technology Transfer The following tool recommendations and process was made to LEAD: Proper cutting tool Proper cutting parameters and conditions Expected Benefits from the new Tool Geometry Increased productivity (119 inches / minute from 70 in. / min.) Better part quality (no delamination, or water impregnation) Better utilization of machining equipment