The slow but steady ascent of additive manufacturing (AM) into mainstream production environments is changing how products of all kinds are designed, made, and delivered. The evolution of advanced materials is further elevating the industry by empowering end-use parts and products with improved physical properties for greater utilization at lower costs as well as faster delivery and less waste.
According to research firm SmarTech Analysis, polymer AM technologies are forecasted to move into a multitude of industries over the next decade, with print production growing to nearly $26 billion annually by 2030. In compiling research, the industry watcher looked at AM polymer parts spanning prototypes, tools, and tooling, as well as end-use production parts across eight industry segments, including automotive, aerospace, consumer goods, energy, and medical.
In particular, the polymer science involved in developing additive materials for 3D printing is inherently more complicated than the science used to produce materials for traditional manufacturing. Moreover, today’s 3D-printing platforms often lack the stringent process controls found in CNC and injection molding, which adds another layer of difficulty.
Tracing the trajectory of additive materials is inextricably linked to emerging processes to extract greater value from existing and new polymer combinations. A holistic look at both is key to closing market gaps while ushering in new manufacturing innovations.
Prioritizing Polymer Science
As adoption of AM accelerates, so does demand for new and improved materials, as well as proven use cases and performance validations. One of the biggest constraints currently is the need to increase the availability of better-performing materials. Companies that prioritize polymer science will be among the first to disrupt the market by elevating commodity resins with value-added attributes to improve usability for a larger swath of applications.
Among the most frequently used plastic materials, ongoing developments are taking place with polyamides (known as nylons), ABS thermoplastic (acrylonitrile butadiene styrene), PLA (polylactic acid), and PC (polycarbonate) materials. Each of these has distinct advantages and drawbacks in terms of polymer properties, performance characteristics, and printability.
Many, if not all, of the most popular additive materials can be enhanced through refinement of polymer formulations and compounding processes. Highly specialized skills in controlling the morphology and particle crystallization are needed, requiring chemists and scientists to create and iterate new material formulas.
For example, Nylon 6/6 is one of the most widely used commercial nylons for injection molding. As a highly crystalline polymer, Nylon 6/6 experiences high rates of shrinkage, which is why it is typically used to produce relatively small parts. The ability to modify the crystallization kinetics, however, can extend the use of this stable, proven material to produce larger form factors.
Similarly, the ability to induce crystallinity in polymers that are typically amorphous, such as polycarbonate, opens the door for these materials to be produced using Selective Laser Sintering (SLS), which is a popular 3D-printing platform within the powder-bed fusion category. The result is the production of an amorphous polycarbonate material that exhibits the high toughness and clarity of an injected-molded polycarbonate part in a much lighter form factor.
Defining the Polymer Value Chain
The polymer value chain extends from chemical creation to formulation, form-factor conversion, distribution and manufacturing method, ranging from 3D printing to traditional molding, extruding, milling or powder coating. Optimizing additive materials for all types of manufacturing is no easy feat.
For that reason, polymer scientists are entering uncharted territories to improve material strength, ductility, durability, chemical and moisture resistance, weight, and sustainability while lowering costs. This requires careful coordination and calibration of chemistry, polymer engineering and manufacturing processes to modify the architecture and method of material creation and formation.
Rapid material iteration and constant fine-tuning is required to tweak mechanical, physical, and thermal properties. As with every manufacturing process, the starting point is the application, closely followed by the business case. Together, these critical parameters help dictate the design methodology, along with material and manufacturing process selection.
In the world of AM, breakthroughs in polymer innovations are being driven by the demand for more affordable, lighter and higher-modulus composites as well as the ability to print materials that previously were too difficult to integrate into additive processes Additionally, the incorporation of value-added attributes to existing polymers is ushering in a new class of engineered materials with special functionality, such as flame-retardant or resistant attributes; reinforced materials containing glass fiber, as well as mineral fillers, carbon fiber, or nanotubes.
The inclusion of conductive attributes also is on the rise to address Electrostatic Dissipative (ESD), EMI-shielded or electrically conductive materials. The need for lubricated materials also is vital to reduce part friction and wear, along with the addition of UV-stable materials to reinforce part longevity. Many of these attributes are designed to extend the usefulness of materials for traditional manufacturing and 3D-printing applications, and vice versa.
Spotlight on Sustainability
The opportunity to boost material sustainability is gaining significance for all the right reasons. For starters, companies are beginning to care more about where their materials come from — are they petrochemical or bio-based? PLA, which is extremely easy to use, is based on renewable resources, such as corn, sugarcane, or sugar beet pulp. Polyamide 11, or PA 11, one of the most widely used additive materials, is a bioplastic made from castor oil. In contrast, PA 12, another commonly used plastic, is a petrochemical-based material, as is ABS, among others.
While materials made from renewable resources can reduce carbon footprints, they are not necessarily biodegradable. As the downstream side is vital, it is critical to consider whether materials can be recycled or composted once a part or product reaches end of life. For single-use plastic items, the type of material is a big concern, which is driving significant interest in the use of home compostable, bio-degradable and marine degradable materials. Ongoing research and development in formulating biodegradable polymers and additive materials focuses on how best to meet strict temperature, oxygen, and water-barrier properties.
The use of post-consumer recycled materials to create filaments for AM also poses process and cost considerations. The morphology control to compensate for the inherent flaws and defects of recycled materials is complicated, especially when dealing with rigorous mechanical requirements. Luckily, efforts to repurpose and recycle powders and other materials used in AM are less complicated, and therefore, growing faster.
Lightweighting and Localization
The ability to reduce carbon footprints by decreasing product weight and localizing manufacturing are prime benefits of AM. It is now possible to create extremely intricate geometric forms with fewer parts for bill-of-materials (BOM) consolidation. Moreover, scientists are experimenting with different chemistries to improve how fillers can be applied throughout the polymer chain to create stronger yet lighter materials.
A great example is the work of carbon-fiber fillers, which can be bonded throughout the complete polymer chain to enable a much higher load transfer to the fibers. This achieves significant improvements in material strength, requiring less material to be used. Ultimately, fewer resources are needed to produce stronger yet lighter parts or products at reduced cost, waste, and energy consumption.
While lightweighting has been a major accelerant for AM applications in the aerospace, automotive, and healthcare industries, now it is picking up speed in consumer electronics. Localization is another important driver as it offers the chance to manufacture and deliver goods closer to end-customers to streamline supply chain management, decrease logistical costs, and reduce carbon footprints.
New eco-friendly materials also are garnering interest for significant environmental benefits over incumbents. An example is an innovative polyketone that can deliver the durability and strength of PA 12 but is made from carbon monoxide, which helps remove this atmospheric pollutant from the environment.
Other innovative materials can reduce and/or eliminate toxic fumes and emissions that potentially are harmful to people and the planet.
Repeatable, Reliable Processes
The use of highly specialized material science, advanced formulations, and compounding processes are essential ingredients to the ideal recipes for additive materials. Where the rubber meets the road, however, is the ability to validate and certify these materials for optimal performance on various 3D-printing platforms.
Rigorous process control is mandatory to ensure much-needed reliability and repeatability of crucial characteristics, such as mechanical performance and dimensional accuracy. Systems integration across different processes and platforms is essential to ramping production volumes while ensuring seamless testing, quality inspections, and post-processing.
In this regard, the AM industry lags behind traditional manufacturing, which uses high levels of automation, intelligent process control, machine learning, and data analytics. Sophisticated manufacturing lines continuously monitor and adjust production processes to ensure top-quality outputs. To achieve similar levels of consistency and quality from AM will require ongoing investment and innovation.
Internal specifications and industry certifications for additive materials and processes are needed to propel the industry forward. While the rules are still being written, there are lots of examples emanating from materials innovation centers and manufacturing centers of excellence to help inform and guide development of best practice and next steps.
Organizations with experience and expertise in additive and traditional manufacturing are poised to provide the best of both worlds. Not only can these experts empower customers to capitalize on the transformative power of additive materials, they also can apply the ideal mix of manufacturing solutions to produce better-performing parts and products at decreased cost and with less waste.
Luke Rodgers is Senior Director, Research and Development, Jabil (St. Petersburg, FL). For more information, visit here .