JEC COMPOSITES MAGAZINE - Issue #50 - July/August 2009 - 18

EQUIPMENT Cutting tools Custom-coated carbide tools for improved adaptability and lower costs The development and application of carbon-fibre-reinforced polymer (CFRP) composites as aircraft skin and structural parts has been a priority trend in aerospace manufacturing for more than a decade. Lightweight and very tough, CFRP parts can now be moulded or even fitted with smart circuitry. However, they still need to be machined along with other basic composite building materials to achieve a precision fit and to accommodate for fasteners or other means of assembly. Focus is now placed on the machine tools used in this critical aircraft manufacturing step because high-carboncontent composites cause rapid tool wear, which results in slower production cycles, high tool costs, and higher overall project costs. ANDREW GILPIN, PRODUCT DEVELOPMENT MANAGER, AMAMCO TOOL (GREER, SC, USA) esearch and testing show that just as the composition of composites is complex, so is the machining process. But there is good news! As the recent case study below illustrates, several controllable factors have been identified which provide the key to lowering tool costs and increasing production speed. These factors are cutting edge hardness and toughness, cutting geometries, and reduced friction at the cutting surface. R greatly from one composite to the next. This explains why manufacturers are increasingly exploring custom-designed tools built to penetrate quickly and perform efficiently within the composite matrix. The case history below set out to identify the cutting tool best suited to the composition of composites and the tool’s ability to adapt to the set-up conditions on the production floor. The results may change your perception of the hardest material known to man. The tool in question was a polycrystalline diamond (PCD) drill, a tool that has been popular in the industry due to its long life cycles. However, as the case history indicates, diamond-coated tungsten carbide was chosen not only for its hardness, but also for its adaptability to the process application. Lockheed Martin Aeronautics Co. had decided to change its entire process, which provided an excellent opportunity to test a coated carbide drill. Because of the dramatic results already achieved with a coated compression router in a different process, tests were performed to determine if similar results could be achieved with an Amamco composite drill. As test results show below, huge lifespan margins for coated carbide over the PCD tool contributed to Lockheed’s selection of CVD diamond-coated carbide as the preferred tool for machining the F-35 composite wing parts. The composite challenge CFRPs are built of layered carbon fibres that are arranged in specific patterns for flexibility and strength. These often diverse layers are stacked upon one another, causing the composite to behave very differently from traditional materials such as steel or aluminium, the hardness of which is generally consistent and predictable from a tool’s point of entry to its exit. By contrast, the fibre content, composition and ply direction all vary The Lockheed F-35. Case history – Lockheed examines an F-35 production process Lockheed Martin Aeronautics Co. manufactures components and manages the assembly of the F-35 Joint Strike Fighter. This next-generation fighter jet is being developed by the USA together with eight other partner countries and is expected to be in full production later this year. 18 jec composites magazine / No50 July-August 2009

JEC COMPOSITES MAGAZINE - Issue #50 - July/August 2009

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #50 - July/August 2009