Additive manufacturing (AM), also known as 3D printing, is a cutting edge technology that creates a physical product by adding material layer by layer according to its digital representation read from data stored in a CAD (Computer Aided Design) file. There are several advantages to utilizing this manufacturing method over conventional subtractive methods, which remove material using a cutting tool or laser. One advantage is speed to market. AM can deliver in days, products that would normally take weeks or months if manufactured conventionally. Another is the ability to create more complex configurations with lighter weights, resulting in superior performance characteristics. Also, the shorter cycle times and lower part counts achievable with AM can lead to lower product cost.
The integration of additive manufacturing at Raytheon is an enterprisewide transformation focused on advancing AM across the company, from a research application to a customer product solution. Creating the processes and infrastructure to advance a new technology from prototype development to qualified production is foundational to the COE mission—examining the entire product lifecycle as it relates to AM. Utilizing AM involves implementing new design philosophies, investing in manufacturing capabilities, creating and understanding the materials database, and developing robust product qualification plans.
Historically, the hardware design community utilized AM for prototype development, shortening the cycles of learning. For example, by printing a piece of a design in days, an engineer is able to test within a short timeframe and receive instant feedback on the overall design. AM in rapid prototyping allows for more design spins during development and the opportunity for engineers to create better designs. However, making the leap from prototype to production hardware requires a new approach.
AM as a production technology is not just an investment in capital or technology, it is also an investment in the culture and processes of an organization. Organizing for innovation can be as important as the innovation itself. Raytheon has maintained a strategic focus on people, processes, tools and capital while taking a holistic approach from product selection to design, manufacturing, qualification and inspection.
Designing for AM includes a different philosophy and approach. Mechanical hardware designers are generally taught to design for conventional manufacturing techniques, such as computer numerical control (CNC) machining, brazing, welding, forging and casting. In AM, however, conventional rules no longer apply and designers must have both different skills and tools. Also, the enhanced complexity available with AM creates new frontiers in the design space. For example, the breadth and types of producible features are greater than those provided in conventional manufacturing designs, and the dimensioning and tolerance methods used are different from those to which conventional design engineers are accustomed. These differences lead to an emerging need for an infrastructure that deploys new design guidance and training, along with associated modeling and analysis tools. Raytheon is meeting that need with both enterprisewide training on AM and program centric groups that hold deep dive workshops, conduct design reviews and assess the fit of hardware and systems for AM solutions.
Equally important to engineering design expertise, manufacturing infrastructure plays an integral role in a company’s AM capability. Careful consideration must be given to the size, process type, and functionality of additive equipment. Many different processes exist in this space, utilizing metal, polymers, ceramics and electronics components.
AM processes require significant amounts of development, not only in the process parameters (layer thickness, power, etc.), but also in the materials themselves. AM provides the opportunity for designers to build complex, lightweight products, but the materials do not have the empirical data that traditionally manufactured materials (e.g. cast and wrought metals) have obtained through the years. An entirely new materials qualification framework, therefore, is required to certify and qualify these materials. In addition to material datasets, product qualification plans need re-examination to make sure they are aligned with new manufacturing methods. A key individual in this framework is an appointed Materials Lead, whose responsibility it is to establish an architecture to assess both the need for materials and the qualification standards required. Characterizing and qualifying additively manufactured materials decreases risk and increases utilization of the technology within programs.
A prime example of AM is its use in the manufacturing of heat sinks. Shown in figures 1a and 1b is an aluminum radial heat sink for a CO2 (Carbon Dioxide) canister used in an evaporative cooling system. The design team chose AM on this project for a better performing part compared to a similar heat sink manufactured with traditional methods. AM also provided a shorter lead time helping to meet key project deadlines.
The Liquid Flow Thru Electronics Chassis1 shown in figure 2 is another example of an AM application developed by Raytheon to leverage the benefits that AM provides. Typical liquid cooled chassis are manufactured through a brazing and machining process where each wall is made separately. Designing the chassis for AM reduced the lead time and allowed the entire chassis to be built as one piece, significantly reducing part count and eliminating leakage between parts. Additionally, the flexibility that AM offers allows the thermal paths to be optimized within the chassis to improve heat transfer.
Beyond the heat sink and chassis, Raytheon envisions other opportunities for leveraging AM technology, whether through thermal solutions, lightweighting of airborne product, printed electronics or large scale additive. The corporate wide AM initiative is helping to advance the maturity of additive in Raytheon—taking design, production and quality systems into tomorrow, and providing more cost-effective solutions and advanced capabilities for our customers.
— Leah Hull, Travis Mayberry & Brian Gahan
1 Monolithic multimodule electronics chassis with multi-planar embedded fluid cooling channels (US Patent Number 9468131)