3D printing is an additive manufacturing (AM) technique for fabricating a wide range of physical products from a computer-generated file.
There are a number of technologies within this broader categorisation of AM, but for the purposes of this introductory guide, we’ll be looking at Fused Filament Fabrication - or FFF for short.
FFF not only represents an accessible, low cost means for manufacturing, but it is also highly versatile. The process and corresponding machines are capable of printing anything from low-cost prototypes to industrial-grade, end-use parts.
UNDERSTANDING THE PRINTING PROCESS
Fused Filament Fabrication is one of the earliest forms of 3D printing and is quite a simple process. The print head on FFF 3D printers uses a nozzle heated to a high temperature, melting a thermoplastic onto the build platform in order to replicate a user generated 3D design, layer by layer.
The plastics used in this process also correspond to the same thermoplastics found in conventional manufacturing processes, such as ABS or Nylon, and choosing the right material will help determine the strength or function of the final print.
The layered process allows for greater flexibility in the design process as well, as the machine could switch between materials with different structural or physical qualities at each layer and effectively combine them. The diagram below shows a simple illustration of the layering process in FFF.
In order to get the final product, it is important that the 3D printer is provided the right instructions to complete the job. This includes slicing software that effectively translates the 3D file into G-code that can then be interpreted by the 3D printer. Software like Canvas not only makes this easy for the user to perform, but also offers additional functionality in working with specific printer profiles or handling multi-material prints when using Palette or Palette-equipped printers like Element.
Once the printer has been turned on, material which comes wound on tightly coiled spools is either manually or automatically fed into the print head. The print head then heats up the thermoplastic to the desired temperature and with the assistance of the extruder is pushed through a fine tipped nozzle. This step makes the material pliable while also shrinking it down for fine detail.
The entire print head is attached to a series of motors and pulleys which comprise the motion system. The motion system guides the nozzle across the build platform (using the before mentioned G-code file as instructions) in order to create the physical model with the melted material. As the model builds up layer by layer it hardens as it cools and once the entire model has been replicated a final product ready to be removed from the build platform.
MATERIALS
One of the greatest advantages FFF technology has over other AM techniques is the generally large and cost-effective repertoire of available print materials. Some require an all metal hotend capable of reaching incredibly high temperatures, while others also need a heated build plate to promote adhesion and a heated chamber to prevent warping.
While most of the recommended thermoplastics are non-toxic, filtration may be needed for others to remove any odors generated from the printing process. While all of the above are important factors to consider prior to printing your file, the quality of a 3D printer’s components itself also plays a large role in the success of printing the various materials FFF offers.
For prototyping and non-industrial use, the most commonly used materials are PLA, PETG and ABS. PLA represents one of the more sustainable, creative, and consumer friendly materials. While its structural qualities aren’t anything to write home about, it’s easy to manufacture in a wide number of colors and its lower cost makes it suited for prototyping, testing and tinkering. PETG offers greater structural strength over PLA. It is very similar otherwise as both are very easy to work with before, during and after a print.
Fixture printed in CF Nylon
More advanced thermoplastics like Nylon, CF infused polymers, and PC are also commonplace in professional-grade FFF printing. They offer various structural benefits over the above thermoplastics, but at the sacrifice of cost and higher demand on printer specifications and temperature control during printing. They also often fill niche roles like high optical transmission, high strength/rigidity, and/or offering the highest aesthetic quality in the final print.
FFF can also make use of industrial-grade materials like PEEK, PEKK and PEI 9085. These represent the strongest, and most heat resistant print materials but at the same time are the most demanding to print, cost the most per cubic centimeter (CC) and often add an additional post-processing step of annealing.
THE NUANCES OF 3D PRINTING
Smart Design
When building the 3D printed part or file, there are a few things to consider in the design phase in order to ensure a successful final print. This remains true for most 3D printers, but there are also special considerations for the usage of Palette or multi material printers like Element.
One of the more common printing issues is warping. Plastic expands when heating and contracts while cooling, so corners and flat surfaces on a print are prone to warping as this process takes place. The inclusion of ribs, filets and a rounding of corners will help combat this.
Printers with a temperature controlled (heated) chamber can also reduce the risk of failure by maintaining a consistent environment for the model to be built up in. The size of the part is also something to consider. While it is possible to print small parts and structures with FFF technology, it is not without its limits. A general rule of thumb is to maximize the thickness of walls and other typically thin sections of your part as often as possible to prevent warping or other structural issues.
Printed Supports
Although it can be difficult to imagine printing in a 3D space, supports will often need to be
included when working with overhangs or any design that has floating elements. For compatible multi material printers, specialized materials can be incorporated into the job in order to simplify post-processing.
Soluble materials can be dissolved off of prints in a water or alcohol bath. Breakaway materials are also often used. These provide just enough support to reduce the overhang angles, but can be easily broken off the main material by hand during post processing.
Post Processing
Given the nature of the FFF process, certain materials may require additional work outside of the printing step in order to get them ready for real world use. For most oddly shaped prints, support structures will need to be removed.
Beyond that, most aesthetically centered prints in lower grade materials can be safely sanded to the desired smoothness, or painted if required. In the case of prints using materials like PEEK and PEKK, annealing is recommended. This is a specialized heat treating process that lowers hardness and improves durability.
WRAP UP
FFF offers one of the most powerful AM methods, given its versatility, ease of use, general
accessibility, and low operating costs. Desktop machines with paired down feature sets are readily available and make high-volume print farms a reality. Automated FFF machines like Array balance out the equation by giving manufacturers the ability to mass produce at a much smaller footprint. The quality and variety of materials also makes FFF AM the premier choice for a growing number of applications and manufacturing demands. From revolutionizing garment making, to empowering 3D Printing service bureaus, and helping educate the engineers of the future; FFF truly has the power to change the way we make.
Ready to get started with FFF?
Mosaic offers a number of products that leverage FFF technology to the fullest. Contact our sales team at sales@mosaicmfg.com to learn more about these technologies. Additional information can also be found on our website at https://www.mosaicmfg.com/
