3D Printing in Space (2014) / Chapter Skim
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3 Technical Challenges for the Use of Additive Manufacturing in Space
3 Technical Challenges for the Use of Additive Manufacturing in Space
Pages 41-60
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From page 41... ...
MATERIALS DEVELOPMENT AND CHARACTERIZATION Although a wide range of homogenous and heterogeneous material mixtures are employed in additive manufacturing, there is still a need for developing targeted materials for use with each specific technique. New physicsbased models of additive manufacturing processes are needed to understand and predict material properties and help optimize material composition.
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From page 42... ...
The opportunity for NASA and the Air Force is to invest in systems that produce open-system design, planning, simulation, and analysis tools. Some reports indicate that substantial savings can be obtained using a design-flow process: a 30 percent reduction both in overall production cost and time to market; 25 percent savings in plant and facility layout; 30 percent cost savings in labor utilization; 35 percent cost savings in optimized material flow; and 15 percent savings in improved quality from validation of processes prior to production.1 Recently, Boeing designed the 787 aircraft through extensive use of such simulation software.
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From page 43... ...
However, even simple, monolithic metal objects of masses greater than about 1,200 kg built with additive manufacturing techniques with the finest resolution require a full year to fabricate. Based on data from current additive manufacturing manufacturers, use of other materials such as plastics or composites will require even more time than metals at these resolutions.
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From page 44... ...
A standard approach to qualification and certification of finished parts will simplify the application of additive manufacturing to the space environment and also enable more widespread application on Earth. ADDITIVE MANUFACTURING AN ENTIRE SPACECRAFT ON THE GROUND Current approaches to complex, multi-material, and multi-functional additively manufactured parts can involve embedding a circuit board, motor, or other subassembly into the process when and where it needs to be integrated.
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From page 45... ...
Although they may incorporate additively manufactured components, the next major challenge will be additively manufacturing major subsystems on the ground. SOURCE: Courtesy of Lockheed Martin Corporation.
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From page 46... ...
additively manufactured spacecraft structure and (2) additively manufactured structure with embedded electrical conductors and components.
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From page 47... ...
quality rating of 5-7 requires precision grinding of balls and bearing races to achieve the necessary surface finish. This quality is not achievable with current additive manufacturing processes (Figure 3.3)
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From page 48... ...
TRANSITIONING ADDITIVE MANUFACTURING TECHNOLOGY TO THE SPACE ENVIRONMENT There are many fundamental questions that need to be answered before additive manufacturing can become widely applicable for routine Earth-based manufacturing. Once ground-based additive manufacturing technology has matured enough to be a viable process for aerospace applications, a logical step forward is the transfer of the technology to the space environment.
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From page 49... ...
The most fundamental technical issue that will have to be dealt with when moving the additive manufacturing capability to space is the effect of zero-gravity or reduced gravity on the manufacturing process and hence the properties of the final product. Each technology will have different challenges in adapting the processes to an environment where gravity is not available as a control variable.
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From page 50... ...
The facility provides shelter from the elements as well as a stable environment, power is delivered, human beings provide means for machine preparation and post processing and qualification of parts as well as clean up and reset of the process for the next production run. When considering the transfer of any additive manufacturing technology to the space environment, some attention will have to be focused on what level of infrastructure will have to be constructed to support the manufacturing capability.
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From page 51... ...
Power Not only will additive manufacturing equipment need power for manufacturing operations, but the platform itself will require power to support the manufacturing process and subsystems involved in maintaining the platform. Power systems readily available to operate in a space environment include solar and nuclear.
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From page 52... ...
For example, if the completed product has to be transported to a different orbit, that will require fuel and a transfer spacecraft. AUTONOMY The level of autonomy that is necessary in a space-based manufacturing platform designed to build a satellite using additive manufacturing techniques will obviously depend heavily on the operational concept derived for the factory.
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From page 53... ...
Additively manufactured parts also require post-processing steps that humans currently fulfill as well as cleanup and reset of the equipment for the next production run. A concept of operations assuming a limited human-in-the-loop requirement will reduce the complexity of autonomy required in a long-term, space-based manufacturing process.
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From page 54... ...
CHALLENGES RELATED TO ADDITIVE MANUFACTURING ON THE INTERNATIONAL SPACE STATION The ISS provides a convenient and natural platform for the evolution of additive manufacturing to a spacebased environment (Figure 3.4)
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From page 55... ...
One of the main technical issues with additive manufacturing is induced thermal stress during the processing. Placing the processing in the extreme thermal environment in space will only exacerbate thermal issues.
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From page 56... ...
56 3D PRINTING IN SPACE FIGURE 3.5 The Japanese Experiment Module, also known by the nickname Kibo, features an exposed facility that can serve as an experiment platform for additive manufacturing. SOURCE: Courtesy of NASA.
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From page 57... ...
Once the many terrestrial-based problems have been solved, and after the subsequent completion of a development program that adapts additive manufacturing techniques to an external platform on the ISS, the fundamental technology, process parameters, and basic equipment design required to build a space-based manufacturing capability around additive manufacturing should be well understood and demonstrated. The level of further development that is required to fully use additive manufacturing to build a spacecraft on orbit is more related to the required autonomy necessary to support the complete manufacturing process.
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From page 58... ...
ADDITIONAL CHALLENGES RELATED TO IN SITU-BASED PLATFORMS Many of the technological hurdles associated with moving additive manufacturing from a terrestrial environment to a space-based environment will also facilitate the adaptation of this technology to other space uses. A natural use of additive manufacturing techniques for the purposes of human exploration is for in situ resource utilization on planetary bodies where humans want to establish a presence.
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From page 59... ...
are two spacecraft that could be used as free-flying research platforms for additive manufacturing experiments. SOURCE: Courtesy of NASA.
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From page 60... ...
Based on evidence that a basic analysis along these lines was already attempted within the Air Force, the committee believes that further coordinated work could potentially help clarify research funding decisions. Recommendation: When considering moving additive manufacturing technology to the space environment, any person or organization developing plans should include in their planning the infrastructure required to enable fabrication processes based on additive-manufacturing, such as power, robotics, and even human presence.
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