Reaching the end-use parts application space
So how will additive manufacturing reach out into an end-use parts application space? The key lies in the advancement of materials, according to industry veteran, Dr. Paul Jacobs. Dr. Jacobs, who formerly operated as VP of R&D at 3D Systems (DDD) and authored THE SLA guide, Rapid Prototyping & Manufacturing: Fundamentals of Stereolithography (considered to be the 3D printing “bible,”) reflected on the state of the industry after the first commercial systems were launched. He notes, “Two themes stick out from rapid prototyping conference proceedings from the early 90’s: First, the need to improve printed part accuracy, and second, that improvements in available materials were desperately needed in order to break into printing functional parts.” In the past 35 years, the industry has raised the standard on part accuracy and consistency, with SLA/DLP technologies still in the lead, but the overall system architecture hasn’t evolved with functional materials in mind.
One testimony to the lack of advanced materials in the 3D printing space is the limited availability of composite resins, polymers filled with functional additives that increase performance in specific ways. If you look at injection molding compounds, the highest value materials are fundamentally composites: glass-filled nylon, Torlon®, ceramic–filled PTFE, etc. By comparison, additive manufacturing is still printing commodity plastics that aspire to perform like ABS, polypropylene, and nylon. Until the performance gap between materials available in AM vs traditional manufacturing is closed, many technologies will stall out when trying to make the jump from prototyping and tooling to end-use part applications. At Fortify, we view this gap as an opportunity to apply innovations in hardware and software towards opening the aperture of what materials can be printed.
While advancing materials available for AM is a clear need, there are several interdependent factors that ultimately determine whether an additive process can scale for a given application. I’ve found the following framework to be useful to predict the success of an AM application. The framework involves three main factors: manufacturing demands, geometric complexity, and material capabilities. Finally, after considering these variables together, it is important to evaluate market size for any given application to determine if the final use case will truly create a disruptive technology.
Questions to consider when evaluating an application for manufacturing demands are: can the process in question print the desired part and meet the necessary specifications including size, accuracy, resolution, and tolerance at the needed quantity? Additional factors include process repeatability, cost, and throughput. These criteria are often competing against benchmarks set by conventional manufacturing processes, and typically are what determine the crossover point when comparing AM and a conventional manufacturing process, illustrated below.
There is an often-misunderstood adage that “complexity comes for free with additive manufacturing.” The general idea is that the more complex a geometry, the better suited it is for AM because the cost of manufacturing increases in conventional manufacturing but stays flat for additive manufacturing. However, most people forget that this is typically a bug of AM processes, not a feature. For an application to be disruptive and a true fit for additive, the design complexity must add some type of value that can’t be achieved by conventional manufacturing. This ‘bug’ of favoring geometries of greater complexities in AM can be leveraged to create unique value. Examples of this include intricate part consolidation (the most famous example being the GE LEAP engine), material and weight savings through topology optimization, conformal cooling in tooling, etc.
No matter how far manufacturing and design capabilities evolve, at the end of the day, you need to have a material that can meet the application needs for a disruptive use case. In ideal cases, materials performance is elevated by design for additive manufacturing and creates “architected materials” – which we’ll cover in more detail in a later article. Material capabilities can be determined from a standard stress-strain curve: strength, stiffness, and elongation. In addition to these mechanical aspects, environmental specifications play a significant role for end-use parts, driving requirements in thermal performance (heat deflection temperature), water absorption, and even biocompatibility. Compared to traditional manufacturing, the current state of functional polymers available for additive manufacturing is a fraction of what is possible across mechanical, thermal, electrical, and other specifications.