You wouldn’t use a pair of scissors to cut a tree, and you wouldn’t use a chainsaw to cut open a gift box. 3D Printing, or Additive Manufacturing, by virtue of being a complementary force, is often compared to other mediums of manufacturing. The vast majority of these comparisons, such as the recent piece by Sculpteo, When is 3D Printing the best solution for production, try to differentiate the processes of 3D printing from injection molding. These posts generally claim the following: 3D printing allows for more complex structures, lower startup costs, rapid turnaround and reduced waste, However, 3D printing suffers from an Achilles heel, speed per cycle and, in many cases, initial surface finish. Mass production techniques on the other hand have higher surface quality, and lower cost per unit, but also have high startup costs and times.
While this may be a fair comparison of injection molding and 3D printing, it is hardly a fair comparison between 3D printing and the so called “traditional manufacturing” methods. I’m certain anyone who has built a birdhouse, or shelving unit, or a planter’s box can attest that 3D printing is not the only method capable of producing usable objects in a short time frame.
Does 3D printing have it’s advantages, absolutely. However it also has challenges that go far beyond occasionally mediocre surface finish or long build times. In order to better understand how 3D printing fits into the manufacturing ecosystem, we will dive into understanding the main types of 3D printing, some manufacturing technologies that compete with or can complement 3D printing, and where it is best to consider using it.
3D Printing can be broadly categorized into 7 types of technology. FDM (Fused Deposition Modeling), SLA (Stereolithography), SLS (Selective Laser Sintering), PolyJet, Binder Jet, DMLS/M (Direct Metal Laser Sintering/Melting), and LOM (Laminated Object Manufacturing). Each one of these technologies has its own advantages and disadvantages. And since each one of these is a distinct fabrication process, it would be unfair, and unwise, to compare all types of 3D printing to all types of traditional manufacturing with large umbrella terms.
Traditional manufacturing techniques can achieve a great deal of things, like finer and more detailed resolutions than what most 3d printing technologies can produce. One of the reasons for this, and one that makes the phrase “traditional manufacturing” largely useless, is because traditional manufacturing encompasses everything from using a drill, to an injection molder, saws, hammer and nails, or laminating fabrics, and so on. In fact, all types of manufacturing that aren’t 3D printing could be considered as traditional manufacturing. Even if we limit ourselves to plastics, silicone molds or vacuum forms remain as valid options, among several other means of fabrication. The differences between injection molding and FDM printing have been clear cut and easy to understand (as seen in the Sculpteo article above) and, as such, have often been the crux of comparison between 3D printing and other manufacturing technologies. This made sense for a while, as the most accessible 3D printers were the FDM machines, which printed in a few types of plastic, however, as 3D printers and the softwares to run them become increasingly affordable,they compete with a wider range of other fabrication technologies. Most notably, in recent years metal 3D printing has grown, which challenges methods such as investment casting and forging and has been revolutionizing the aerospace, automotive, and medical industries. However, it still remains out of reach for most consumers. Stereolithography, on the other hand, has now found its way to the consumer market. While it is limited to the most proficient and invested consumers of domestic 3D printing, it offers a drastically different toolset than FDM printing. Additionally, people with access to industrial grade 3D printers are now offering their services to the general public, making access to technologies such as nylon sintering or poly jetting much more accessible. Each of the 3D printing methods also has its own set of restrictions in terms of what it can build, how it can build it, and what features add or take away from cost, adding further complexity to the comparison between 3D printing and “traditional manufacturing”.
Additionally, we must look at ways in which all fabrication and manufacturing processes (including 3d printing) can work in tandem. For example, one could 3D print a blank, which can be cut down to a specific size, or get machined down to tighter tolerances (which is actually how much of metal printing is done). On the other end of things, An injection molded item could be augmented using 3D printed parts for uses with different applications. Fabrics or other materials can be laminated onto and in between 3d printed pieces to make up for the lack of tensile strength in a printed objects’ z-axis.
The rest of the series will explore, in depth, each of the 3D printing technologies and various methods of fabrication that compete with or complement them. Stay tuned for part two, where we will take a deeper dive into the currently available domestic 3D printing technologies, FDM, and SLA.