Guide to Additive Manufacturing — Layering to Post Processing
Part 1: The Basics
Introduction: What is AM?
Additive manufacturing (AM) creates objects by adding material together, bit by bit, until completion. Think of how a house of bricks is built—additive manufacturing builds objects in a similar way, starting with very small pieces of material and combining them, layer by layer, to form a larger finished project.
Additive manufacturing is an ideal approach for making items out of plastic, metal, ceramic and other materials. It allows rapid production of parts, both finished products and prototypes. It reduces the cost of low-volume production runs. It also creates parts with complex shapes that can’t be made by traditional processes.
Recently, a rocket with 3D printed parts was successfully sent into space. By reworking the ducting system using AM parts United Launch Alliance was able to reduce the assembly to 16 parts from 140, which meant a cost savings of 57%.
The Steps to Additive Manufacturing Success
The process of making an object involves three main steps: modeling, printing and finishing.
Here is a simplified breakdown of the individual steps, and what they are comprised of:
- Modeling creates a computerized 3D design of an object. The 3D model is created with a CAD program then depending on the process chosen, could be converted to STL. Finally, once the digital model is finalized, the design is loaded into a printing machine where it guides the printing process.
- In Printing, machines use additive processes to create a three-dimensional object. There are many printing processes, described below, each with its own strengths.
- In Finishing, printed objects are prepared for use. This may involve rinsing, polishing, painting, smoothing or other tasks. One of the main differences when selecting an additive manufacturing service bureau is the quality and level of finish they can provide on each process.
Industries Currently Using AM
Additive manufacturing is common in many industries, with new applications being developed every month. The future is clearly limitless.
Here are some of the most common industries served:
- Vehicle: Parts for automobiles, aircraft and railcars, from titanium car exhausts to lightweight aviation.
- Medical: Additive manufacturing excels at many of the design elements used in medical devices from prototypes to finished products and is ideal for creating curves, internal chambers and channels.
- Consumer Goods: Highly stylized jewelry, décor and personal items are possible.
- Manufacturing: Replacement parts for industrial equipment extend the life of machines and reduce the cost of maintenance.
- Electronics: Ultra-precise plastic and metal components for computing, communications and more.
Additive Manufacturing Processes
Depending on the specific industry and application, a variety of AM processes can be utilized. The process chosen is dependent on the material used and complexity of the end-product.
Here are descriptions of typical Additive Manufacturing processes:
- Stereolithography: A UV laser traces a pattern on the surface of liquid photopolymer resin, solidifying the resin into a pre-programmed shape. Then the hardened layer of resin is withdrawn into the liquid, and the process is repeated to add another layer to the part. The process is repeated until the part is complete.
- Selective Laser Sintering (SLS): A laser traces a pattern on powdered nylon to fuse the material into a solid structure. New powder is applied atop the hardened material, and the process is repeated to add layers to the part until completion.
- PolyJet: Think of an ink jet printer for polymers. The printer shoots droplets of photopolymer onto a build tray, and each droplet is instantly hardened with a laser. Droplet by droplet, the printer “builds up” a part.
- Fused Deposition Modeling (FDM): Think of a hot glue gun: A long thread of plastic filament is fed into the heated nozzle of the printing machine. The nozzle melts the material and deposits it on a build tray, layer by layer, to “build up” a part. FDM, or Fused Deposition Modeling™ is also known as FFF or Fused Filament Fabrication.
- Urethane Castings: Additive manufacturing is the preferred way to create master patterns for urethane casting. Using the techniques above, you can create a master pattern faster and less expensively than with CNC machining. Additive manufacturing also lets you create more complex master patterns, with shapes, holes and grooves not possible through CNC.
- Metal Prototyping: Additive manufacturing enables a variety of metal prototype techniques such as metal casting, and direct metal laser sintering (DMLS). The best technique depends on the project’s manufacturing priorities:
- Metal casting is ideal for rapidly creating short-run metal parts with high accuracy, durability and quality.
- DMLS is ideal for rapidly creating highly complex, intricate 3D parts that would be difficult or impossible to produce with traditional methods.
Additive Manufacturing Materials
A tremendous advantage to AM is the wide variety of materials that can be utilized, thus leading to countless applications and industries. In order to give you an idea, here is a list of the common classes of materials used in the above processes.
- Clear UV resin
- Off-white UV resin
Selective Laser Sintering
- Powdered nylon
- Powdered nylon with glass fill
- Rigid plastics, choice of color
- Flexible plastics, choice of color
- Custom plastics, tailored to the production spec
FDM [FFF ]
- Extruded ABS plastics
- Plastics to replicate the production materials. Many colors and durometers (hardness) are available.
Metal (for casting)
- Steel (Stainless, high carbon, etc.)
Please note that within each class of material, there are many variations (including branded products) available.
Here’s What’s Next!
As you can see, Additive Manufacturing is a simple process with a very complex world of applications, materials, and potential. In the coming years, it is certain that you will find it being mentioned as a mainstream alternative—and complementary process—to traditional manufacturing.
Please review and share this guide with anyone you know who may want to integrate AM into their business, or who simply want to be better informed about Additive Manufacturing.
Don’t miss Part 2 of the Guide to Additive Manufacturing — Layering to Post Processing that will focus on the ideal use of each additive manufacturing technology. Enter your email for our newsletter and we will notify you when it’s available online.