By understanding which 3D printed materials are most suitable for a given project, engineers can take full advantage of the efficiency and convenience of 3D printing.
Daniel Lazier, Strategic Application Engineer, Markforged
The COVID-19 pandemic has had an impact on every industry imaginable. When the 1918 influenza pandemic caused historic loss of life and huge economic disruption, health and safety concerns were a forcing function for entirely new labor patterns and factory workstreams. As manufacturers strained to adapt and maintain business continuity in the face of these challenges, they turned to a 35-year-old technology to make it happen: Electricity.
Looking back at the past few decades, the manufacturing industry has been in a state of malaise, struggling to implement and reap the rewards of a digital transformation enjoyed by nearly every other major vertical. Manufacturing was thus unsurprisingly one of the hardest hit industries in the face of the pandemic due to its lack of ability to respond with agility and geographically localize. This time around, cloud-based 3D printing is the decades-old technology poised to take manufacturers out of the woods and up to new heights of supply chain efficiency and productivity.
Right now, we are seeing one of the most important transitions in the history of the additive manufacturing industry. Manufacturers are becoming empowered and in fact emboldened, through accessible digital platforms that produce parts with all of the applicable mechanical properties for the highest-value engineering applications.
High-strength continuous-fiber composites bring the strength and performance of composite-laminate structures to the engineering desk and the front lines of problem solving. Metal parts printed on Fused Filament Fabrication (FFF) architecture represent a step change in the affordability, safety and design space, opening an entirely new application space for metal 3D printing.
For decades, metal printing was restricted to niche applications where the burdens of exorbitant cost, hazardous working conditions for highly-skilled technicians and specially designed facilities could be overlooked, either due to the incremental performance benefits associated with printing that part, or more often due to the novelty factor of printing these parts with exotic, previously unachievable geometric features. In either case, the applications were limited to a small subset of parts that often took years of effort, millions of dollars in research and development and qualification to implement.
The advent of FFF metal 3D printers has increased the breadth of geometries achievable in a wider range of metal materials, while also drastically reducing the hurdles associated with implementation. With this newfound digital manufacturing capability extended to metal, engineers and designers may not only attack high-flying, future-looking parts, but also some of the low-hanging fruit that represent a larger portion of day-to-day manufacturing work streams, like tools and fixtures that would traditionally be machined in steel on a CNC mill. In doing so, manufacturers cut costs and lead times by 80-90%, allowing them to make product decisions with greater agility.
By contrast with conventional processes, where complexity drives up overhead, setup and labor costs, intricate features come free of charge with this new means of 3D printing metal parts. This newfound flexibility allows manufacturers to explore designs that were previously off-limits with the materials that are most relevant to the problems they face. For example, Guhring is a UK-based company focused on manufacturing precision cutting tools for the world’s largest companies, like BMW, Jaguar, Land Rover, Airbus, BAE Systems and more. When they came under pressure to produce a better-performing cutting tool they printed a version in tool steel that used unique internal passageways for cutting fluid.
The higher speeds and durability achievable with this previously unattainable design delighted customers. Since beginning to use metal 3D printing, the company has saved 66% of time in production and 75% in low-volume tooling costs and seen a 60% tool weight reduction.
Another significant difference between conventional manufacturing and the newer modes of metal printing is the accessibility. Since it is no longer the case that organizations need to build up specialized facilities and operator expertise, metal printers can go anywhere, unlocking enormous value in distributed maintenance and aftermarket parts work streams. Companies like RPG are harnessing this capability and producing legacy parts that are difficult or impossible to obtain from the original vendor. This alternative is financially compelling relative to conventional processes like CNC machining.
Most metal additive manufacturing machines produce parts through fusing metal powder particles. Since free metal particles present numerous risks, including respiratory harm and toxic bloodstream absorption for humans and explosive potential when in contact with oxygen, the feedstock media for the raw material has a significant bearing on the accessibility of the specific type of metal 3D printing.
For example, metal 3D printing can often occur in a three-step process: printing with a bound powder filament; washing to dissolve the primary binding material; and sintering to convert the washed part into its high quality, dense final metallic form. This process allows manufacturers to create fully dense metal parts without the risk of working with loose powders, making it generally safe to use in a shop environment.
One additional strength of this process is its broad material applicability. While there have been a handful of materials that have been industrialized for key applications today, there is an exciting potential future for the technology, which is only limited to the metals that can be powderized and welded.
Of the materials that are currently printable through this technique, stainless steel is among the most commonly used due to its high strength and excellent corrosion resistance. The material allows engineers to print robust parts for a variety of applications, like end-of-arm tools, functional prototypes, lightweight brackets and more.
Printing with tool steels is also a common work stream for anything on a production line that is intended to cut, stamp, mold or form. This material can withstand harsh conditions because of its high hardness and excellent heat and abrasion resistance. However, these benefits do make tool steels difficult and expensive to machine – presenting immediate advantages for manufacturers looking to produce these tools additively.
Copper allows manufacturers to 3D print complex parts with high electrical and thermal conductivity. These parts are expensive, time consuming or sometimes impossible to machine traditionally. This material is best suited for low-volume production parts like bus bars and heat sinks, as well as spot welding arms, which require high electrical and thermal conductivity.
Within the superset of metal parts manufacturing, metal 3D printing today fits into a subset of low-to-mid volume production spanning the entire product life cycle. Metal 3D printed high fidelity prototypes, durable tools and fixtures, high performance custom parts, legacy spares, and replacement parts all deliver superior value relative to conventionally manufactured parts.
Composites 3D printing provides yet another alternative to traditionally machined custom high strength parts.
Composites are characterized by the structural integration of multiple unique materials and the resulting mechanical properties of the combined part that are superior to that of the individual component materials. Engineers may create parts with material properties comparable to metals with materials like carbon fiber, along with others designed specifically for high temperature applications. Moreover, these printed structures take advantage of the fiber’s properties on the interior of the part while using the plastic matrix material on the outside of the part, leaving a tough, non-marring surface.
Engineers turn to composites for a variety of applications, including end-use parts where high-strength-to-weight ratios are favorable, as well as everyday work holding and forming tools. Composite 3D printing allows fabricators to produce high-strength custom parts without consuming CNC machine and operator bandwidth. As a result, low-cost tooling and fixturing is possible and parts can handle high loads and machining fluids.
Few materials have the versatility of onyx, a micro carbon fiber-filled nylon that offers high strength, toughness and chemical resistance. For this reason, onyx is the most heavily used plastic matrix material for composite parts. Flame-resistant variants are available, too, which are designed for use in applications where parts must be non-flammable, such as weld fixturing, aerospace clips or brackets and laser marking fixtures. Manufacturers also use white nylon as a matrix material for applications that require even lower abrasiveness.
The library of continuous fibers is flag shipped by carbon fiber. Well-known in the industry for its excellent strength-to-weight ratio, carbon is best-suited toward high performance end-use applications, tools and fixtures that require best-achievable stiffness. Another specialty fiber, called HSHT (High Strength High Temperature) fiberglass, performs well in applications like welding fixtures and low-volume injection molds which expose the printed parts to elevated temperatures. Other commonly-used fibers include fiberglass, which has great properties across the board, as well as Kevlar which has excellent mechanical compliance, durability and impact resistance.
Wärtsilä specializes in smart technologies and complete lifecycle solutions for the marine and energy markets and has a portfolio of products that range from engines to propulsion and renewable solutions. In an example of the strength and versatility of carbon fiber printed parts, Wärtsilä saw an opportunity to save time and money by printing lifting tools for 800 kg engine pistons. They went on to get the tools CE certified, unlocking common use of them in factories all over the globe. As a result, the team estimates that it has saved over €100,000 in tooling alone over the past eight months, and reduced the lifting tool’s weight by 75%, thereby improving worker safety.
Additive manufacturing helps manufacturers speed up innovation and develop more agile processes—factors that played a role in helping them adapt to the pandemic. As 3D printing continues to gain momentum in the industry, manufacturers are finding new use cases for additive manufacturing for maximum business impact.