Lockheed Martin was experiencing difficulties in machining advanced composite wing skin material for the F-35 Joint Strike Fighter (JSF). With tool life lasting only nine linear feet at one-third the total material thickness and excessive delamination of the composite material, existing tooling and processes were unable to produce quality components efficiently.
Faced with growing demand for F-35 composite components, tight manufacturing schedules, and limited machine time to conduct tool testing on new composite materials, Lockheed Martin turned to NCDMM to provide a more efficient machining solution, specifically, improving tooling life and eliminating outer edge delamination.
NCDMM began development of a solution by first building a vacuum test fixture to Lockheed Martin’s specifications to hold the composite test panels provided by them and evaluating multiple cutting tool geometries at varying application parameters. Once cutter geometries and their associated cutting forces were determined, tool life and delamination were measured and evaluated. These test results led to the in-depth understanding of the three key elements needed to provide the best solution—tool geometry, tool material, and the proper tool coating. Working with its Alliance Partners Amamco Tool Company; Kennametal Inc.; and RNDT, Inc.; and in conjunction with Diamond Tool Coating and McCullough Machine, NCDMM was able to combine key technologies and develop a tool that dramatically increased tool life and eliminated costly edge delamination.
Improving tool life and eliminating delamination of the outer edge for F-35 composite parts
With the solution developed by NCDMM and its partners, Lockheed Martin machined a complete wing skin, using only two cutting tools—one to rough and one to finish—instead of 24. Additionally, Lockheed Martin realized increases in cutting distance by more than 6x (from 9 linear feet to 57) at full material thickness, reductions in programming time, and increases in production while decreasing scrap. The cost savings amounted to $80,000 per aircraft. With the expected manufacturing order of 2,723 F-35 JSF aircrafts, the cost savings/cost avoidance translated to $222.6M throughout the projected F-35 build for Lockheed Martin.