Imagine what engineers would create if they were not bound by the confines of traditional manufacturing processes. For those few who are adventurous enough to think outside the box, there is a vast opportunity to revisit, reinvent, and discover new efficiencies in industrial engineering and design that were previously inconceivable. Welcome to the modern revolution of additive manufacturing.
Allow me to paint a picture of a young industrial engineer that has just invented a flow valve with internal cooling channels that reduces heat transfer by 40%. He takes the design down to the machine shop to confer with the foreman, only to be told that his design cannot be manufactured. Even though conceptually the design works, the machinist explains that it cannot be realized because there are no tools that can bore out such narrow integrated channels without detempering (overheating) the alloy. The engineer heads back to his office to adjust the design, frustrated at the limitations imposed by his company, yet quietly confident of his prospects because he knows his design can be realized through an entirely different means of production.
Introducing: Industrial 3D Printing
Direct Metal Laser Sintering (DMLS) uses powdered metals and ceramics that are sintered or melted by a fiber laser, one 5-micron to 30-micron layer at a time, to “grow” fully functional end-use parts. The laser sintering process produces chemically pure, fully dense, precise metal parts with a level of speed and complexity that is unmatched in traditional manufacturing processes. If a metal can be powdered, it can be used in additive manufacturing. Options include metal alloys and ceramics (Steel, CrCo, Inconel, Al, and Ti alloys).
The printer does not care about the intricacies of the design: COMPLEXITY IS FREE!
Where DMLS really shines is producing small intricate parts that simply cannot be manufactured any other way or reducing the number of pieces used in any given assembly. Recently, GE gained FAA approval for their 3D printed metal fuel nozzles on their next-generation LEAP jet engines. The printed fuel nozzles are 25% lighter than its predecessor part and reduce the number of parts used from 18 to 1. Through additive manufacturing, the GE engineers were able to create more intricate cooling pathways and support ligaments resulting in five times higher durability vs. conventional manufacturing. Removing only two pounds from each aircraft of a 600+ fleet of commercial aircrafts could save about 23,000 gallons of fuel annually, cutting down on fuel bills (in 2013, fuel typically absorbed 35% of an airline’s annual revenues). It also avoids the emission of 230 tons of CO2 into the atmosphere, a significant environmental gain.
Above: GE metal 3D printed fuel nozzle for the next-generation LEAP engine.
The use of 3D printing in metal manufacturing expands beyond the build size of traditional DMLS printers. OEMs are able to use stereolithography (SLA) printing, the most mature 3D printing technology, to print custom master mold patterns which are sent straight to a foundry. Developed in the 1980s by 3D Systems, SLA works by using lasers to cure liquid resin (in a vat up to 25 cubic feet in volume), producing parts at a resolution of 4,000 DPI. These printers turn large format designs into master casting patterns in a matter of days instead of months. In the conventional process, the 3D model of the desired part is sent to the tool shop where a tool is created from which wax patterns are molded – a process that can take 7-9 weeks. 3D printed patterns are foundry-ready in five days or less resulting in a six-week savings in the production cycle. The time saved in production allows OEMs to test, redesign, reprint, recast, and prove before parts made with traditional tooling processes would even be available. This tightens up design cycles, removes production lag-time, accelerates time-to-market, and reduces cost.
Above: A SLA printed pattern for a hydroelectric turbine. The printed pattern has a diameter of 39.4 inches and weighs 154 pounds. The final cast model weighs 4,300 pounds.
Where does that leave traditional manufacturing and obstacles of implementation? One issue that our clients have voiced is the lack of 3D printed metal parts’ ability to be tested and certified by American Society for Testing and Materials (ASTM). Well, just last week ASTM announced that additive manufacturing guidelines and standards are coming for industrial 3D printing. “The international committee is working on standards for the mechanical properties of additive manufacturing materials. These guidelines will use currently available standards for measuring mechanical properties including fatigue crack growth and fracture toughness specifically applied to industrial 3D printing.” The result is a manufacturer’s ability to qualify parts and components to meet specific load bearing capabilities, fracture and fatigue properties and damage tolerance using ASTM standards.
The impact of additive manufacturing, in conjunction with nascent certification standards, are far reaching. A few of the industries that stand to benefit are aerospace and defense, oil & gas, shipbuilding, healthcare, automotive and engine component manufacturing, electronics, and turbine production, just to name a few. Whether we are talking about DMLS or SLA patterns sent to the foundry, the end result is the same: an increased ability to turn market pressures into competitive advantages, tighten design and manufacturing cycles while increasing freedom and flexibility to match production to demand, and literally inventing new forms of functionality. The real challenge is foresight: both in seeing the value of adopting this innovative technology as an organization and finding ways to integrate it into your design and production cycles before the competition.