The challenges faced by aerospace components manufacturer
Aside from ensuring extreme precision and accuracy in the production of aerospace components, manufacturers have to face the challenge of the increasing popularity of composites. Airplanes used to be constructed from metals like aluminum, steel and titanium but carbon composites have made a large impact on the aerospace industry. Aerospace components manufacturers have to invest in state-of-the-art technology specifically suitable for machining everything from aluminum sheet stacks to polycarbonate honeycomb.
Composites react very differently than metal during machining because there are a great number of variables that dictate how the composite will react. In machining, the following factors have to be considered like fiber type, resin type, fiber orientation at the point of contact, composite part thickness, matrix hardness and heat sensitivity and the type of composite part construction. Aerospace components manufacturer must take into consideration all these factors in the choice for machining technology and processes that can be adopted for aerospace application.
Cutting tools for aerospace machining
Cutting tool considerations for machining composites vary significantly according to the application whether it will be used as a roughing tool or finishing tool. The baseline tool material is carbide followed by coated carbide. To ensure high performance, suppliers offer diamond-coated tools and tools with polycrystalline diamond coating or diamond-like coating. This high hardness coating can increase costs because a single-coated tool can cost as much as $500 however; it could a trim a composite length that is four times longer. On the other hand, a part that has low fiber volume fraction can cut easily allowing the use of a less aggressive and more cost effective tooling material. When machining a valuable composite structure that is worth hundreds or thousands of dollars, spending $200 or $600 for every tool will not matter.
Tool geometry options are considerably more than coating options. In order to fit the aerospace application, the number of flutes and the angle flute twist are usually customized. Customization will reduce the risks of delamination and will produce a clean edge on both the top and bottom surfaces with very few stray fibers along the edge. Tool geometry is very important in drilling and it usually involves gradients in diameter and/or diameter staging. A drill tool usually has a shaft that increases in diameter from entry point to midpoint. It will drill a small pilot hole and will gradually ream the hole according to the specified size. A three-in-one approach that is often coupled with stack drilling will eliminate potential inaccuracies when two parts that must be joined are drilled separately.
A solution to aerospace components manufacturers is to settle for a tool material that is ideal for one substrate even if it cannot be used on other substrates so that clean holes can be bored through stacked composite aircraft skins and the plane’s titanium or aluminum frame members.