Evolution of Aerospace Materials and Advanced Machining

Demands for airframe and exterior resiliency without sacrificing weight and fuel savings remains the holy grail of aviation. While many materials have been tried throughout the 20th Century to achieve this balance, their use is regulated by aerospace machining provider’s ability to produce them.

Early Attempts at Metal Planes

The world’s first all-metal airplane actually dates to 1915 when aviation pioneer Hugo Junkers built a tubular-framed metal fuselage covered with corrugated sheet iron. Unfortunately, while the metal surface made the aircraft stiffer and stronger, its surface roughness resulted in significant drag. Additionally, surfaces were custom-crafted for each plane, which made them slow to machine and assemble. Sheet metal skin and ribs, held together by rivets, made an appearance in the late 1920s but the usage of these materials for aircraft was still in its infancy.

Age of Aluminum

The 1930s saw the rise of aluminum aerospace machining in aircraft. At the time, the material seemed to have all the right attributes: lightweight, inexpensive, easy to machine, and it featured a modern, sleek exterior appearance. It introduced the era of the silver plane, a term still used within aviation today, often with nostalgia. At one time, nearly 70% of aircraft had skin and airframes made from this metal. Stainless steel construction came soon thereafter, followed by advanced superalloys following WWII and titanium in the early 1960s, mostly for military aircraft. At each step, aerospace machining techniques and processes had to evolve to keep pace with experimental new materials.

Composites Arrive

The first carbon fiber composites were introduced for aerospace materials in the 1970s. They are exceptionally lightweight, yet can be made to a tensile strength roughly five times that of steel. Composite aerospace components are used with epoxy resins and plastic to form a matrix that keeps fibers together as one-piece designs. As a result, these pre-formed components reduce the numbers of joints and heavy fasteners, which are potential weak spots. In today’s aircraft, one-piece designs are used wherever possible.

Aerospace Machining Keeps Pace

New metals and composite materials continue to be developed for lighter weight, increased strength, and for corrosion and heat resistance. At the same time, advances in aerospace machining and cutting are keeping pace with the evolution of aircraft construction. For nearly 40 years, Computer Numerical Control (CNC) machines have greatly contributed to the manufacture of a wide range of aircraft parts, sections or exterior panels. These automated aerospace machining and milling devices make components for aviation use without direct human intervention. Many large and small CNC units exist, from cutters to drills, for producing a variety of parts.

The aerospace machining industry continuously experiments with new techniques and tools to make the latest materials for tomorrow’s aircraft producible on a mass scale.

Extend the Life of Your CNC Machines With These Three Tips

Photo Of A CNC Machine - CMS North AmericaWhen using the CNC machines, it is always good to conduct routine maintenance to ensure a quality output. Some companies are usually so busy serving their customers that they often overlook the need to do maintenance. However, taking the time to perform maintenance helps prevent an expensive breakdown while ensuring the machine’s maximum longevity.

1. Lubrication

Tools such as the spindles, cutters, and other moving parts are used daily. These tools are likely to break, chip, or sustain dents when they are not well maintained. The operator should identify these tools and lubricate them as often as need be. It’s also important to use the right oil or grease to prevent any possible CNC machining problems.

2. Use the Correct Speeds and Feeds

For best results, it is important to run the CNC machine while using the right speeds and feeds. It is necessary to adhere to the manufacturer’s recommendations while taking into account the material, tool’s diameter, the arrangement of inserts, and the width and depth of the cut. Nowadays, companies can use a special “feeds and speeds” calculator to make the selection easy.

3. Do Not Recut Chips

Recutting chips is harmful to the life and security of the machine. Therefore, it should be avoided at all cost. It may also lead to chip jamming and cutting edge fractures. This problem is common when milling deep pockets and cavities on vertical materials. The coolant can be set up correctly to eliminate the chips easily. Additionally, splitting a deep cut into several passes can help solve this problem.

By adhering to these simple maintenance and application tips, companies can ensure their CNC machines are running at the optimum performance while assuring a reliable production process. Inspecting the machine regularly also helps to note parts and tools that may cause potential problems in the future.

Photo Credit: Colin

A Manufacturer’s Guide to Laser Cutting vs. Waterjet Cutting

Photo Of A Laser Cut Pattern - CMS North AmericaLaser cutting and waterjet cutting are the two most commonly used methods of material cutting for manufacturers across all industries. Learn about each of these cutting methods, the machines that perform them, and the unique advantages and disadvantages of each.

Laser Cutting

Laser cutting machines use a gas laser (typically CO2), beamed and directed by mirrors, to cut a wide variety of materials with extreme precision. With CO2 lasers, the source of the laser is found within the laser cutting machine. Laser cutters can typically beam their lasers at an output of 1.5 to 2.6 kilowatts, and because of the fineness of the laser, machines can cut with precision as fine as 0.006 inches depending on the material. Laser cutters can be used effectively on a number of materials, including glass, plastic, wood, and many metals. However, CO2 laser cutters should not be used on highly reflective materials. Instead, solid-state fiber optic lasers, which use amplified light in fiber optic cables, should be used due to their significantly lower refractivity.

Laser Cutting by the Numbers

  • Beam output: 1.5-2.6 kilowatts
  • Maximum cutting slit thinness (precision): 0.006 inches
  • Optimal material thickness range for cutting: 0.12-0.4 inches
  • Materials: glass, plastic, wood, and metals

Waterjet Cutting

Unlike laser cutting, waterjet cutting uses pressurized water emitted at high speeds to cut materials. Often, a granular abrasive such as garnet is added to the water to increase the jet’s cutting power. With outputs ranging from 60,000 to 90,000 psi, waterjets can cut a wide range of materials in varying levels of thickness. Though typically somewhat less precise than laser cutters, waterjet cutting machines do not produce a “heat-affected zone” on the materials they cut where the heat emitted from a laser cutter can warp the material closest to the cut. In instances where thick or highly reflective metal must be cut, waterjet machines are much more effective than their laser-emitting counterparts.

Waterjet Cutting by the Numbers

  • Jet output: 60,000 to 90,000 psi
  • Maximum cutting slit thinness (precision): 0.02 inches
  • Optimal material thickness range for cutting: 0.4-2.0 inches, but with CMS/Tecnocut’s IKC technology (Intelligent Kerf Compensation) added to the waterjet’s cutting nozzle the output tube can be angled so that the waterjet can cut from the side of the cutting stream’s “cone” at a greater depth, since the angle of the cutting nozzle is being controlled to cut with the side of the “cone” rather than from the center of the stream.
  • Materials: virtually any materials to thicknesses over 12 inches

Overall, both methods of cutting offer unique benefits depending on the type of material, precision requirements, and thickness of the cut. Talking with a professional about industry standards, desired outputs, and material usage can offer additional guidance.

Photo Credit: With Associates

4 Advantages of Using Honeycomb Composites

Photo Of A Machining Worker - CMS North AmericaHoneycomb composites were inspired by honeycomb weathering and beehives. Their aim is to reduce the amount of material being used, to consequently reduce the weight and cost of the final product. Honeycomb composites are made from different materials, such as stainless steel, aramid fiber, aluminum, and thermoplastic. They are commonly used in the marine and aerospace industries due to their lightweight and tough designs. The demand for these structures is increasing due to their relatively high shear and compression properties and their low density. Here are four of the advantages of these materials.

1. Reduced Cost

Many businesses prefer these lightweight materials to plastic and wood due to direct and indirect cost reductions. Honeycomb composites are cheaper to buy, handle, package, and transport. Being paper or metal-based products also makes them easier to dispose of while offering recycling cost-savings. This is because they are 100% renewable and recyclable.

2. Exceptional Strength-to-Weight Ratio

Honeycomb composites have become the ideal alternative to wood and concrete, especially in packaging and construction applications. They weigh about 4 to 5 times less than wood and 10 times less than concrete. They are strong and boast a high unidirectional compression resistance.

3. Fire and Fungus Resistant

These materials are usually multi-layered to provide high fire protection. Some structures come with cement-coated cells that ensure maximum resistance. Additionally, they are unaffected by water and most solvents, making them resistant to rot and corrosion.

4. Optimum Thermal Insulation

Honeycomb structures have a higher ability to dissipate heat thanks to their dead air spaces and polypropylene cell walls. This helps to prevent the accumulation of heat in the cells to avoid exceeding the heat deflection temperatures. Some options use foam to achieve even greater thermal insulation.