FFF vs. FDM – What Is The Difference?

FDM Vs. FDM 3D Printing

FFF vs FDM 3D Printing Explained: What Is the Difference?

Written By: Patrick Wirt, Production Manager - April 21, 2021

When most people hear "3D printing," what often comes to mind is the accessible, budget-friendly Fused Filament Fabrication (FFF) technology that has become increasingly popular among hobbyists. However, behind the scenes, a more advanced and precise 3D printing technology—Fused Deposition Modeling (FDM)—has been silently revolutionizing industries, from aerospace to healthcare. Although both FDM and FFF may seem similar at first glance, they are worlds apart in terms of capabilities, precision, and applications. If you've been skeptical about 3D printing or have only dabbled in FFF, prepare to discover how FDM raises the bar, shattering common misconceptions and showing us that 3D printing can be far more than just a tool for hobbyists.

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Fused Deposition Modeling (FDM), a 3D printing technology that has been in existence since 1988. Despite its early development, it wasn't until more than two decades later that the technology truly began to flourish and gain widespread recognition. The catalyst for this growth and more widespread commercialization was the expiration of the FDM 3D printing patent in 2009, which opened the floodgates for the emergence of lower-cost 3D printers. These printers employ a similar but distinct process known as Fused Filament Fabrication (FFF). The affordability of these FFF-based machines made 3D printing accessible to the general public, allowing people to own personal 3D printers. This democratization sparked heightened conversations and interest in 3D printing technology. By 2014, media attention had made 3D printing practically commonplace, especially among hobbyists and tinkerers who began incorporating these machines into their home workshops.

However, unbeknownst to the average consumer, this new wave of affordable 3D printers was not merely a cheaper version of what had been available for the last two decades. Companies like GE, Airbus, BMW, and Ford had been early adopters of FDM 3D printing, using it for specialized, low-volume manufacturing tasks with large, industrial-grade machines. Although FFF printers might appear similar to FDM printers on the surface, the quality and capabilities of their output are quite different.

For engineers, designers, and other professionals who first encounter 3D printing through these budget-friendly FFF printers, there is a risk of developing a skewed or negative perception of the technology's capabilities. If their first experience yields subpar quality in terms of strength, surface finish, or structural integrity, they may become disillusioned with 3D printing as a whole. This could discourage them from exploring more advanced 3D printing technologies, which offer vastly superior results.

The surge in popularity of FFF 3D printing, fueled by media buzz, has also led to misaligned expectations about what higher-end FDM and other industrial printers can truly achieve. This has the unintended effect of undermining the potential and applications of these more robust, industrial-grade machines, which are in a league of their own in terms of precision, quality, and versatility.

What Makes FDM Better?

Fused Deposition Modeling (FDM) machines are large, enclosed systems designed to create parts that require high-quality, engineering-grade prototypes capable of withstanding mechanical loads. The Fortus series of machines by Stratasys represents a high-performance range of FDM 3D printers specifically engineered for industrial applications. Unlike simpler, more affordable 3D printers, the Fortus 450 comes equipped with specialized features that make it uniquely suited for producing engineering-grade prototypes, intricate parts, and specialized production components. Here are some key aspects that set it apart:

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Higher Accuracy

FDM machines by Stratasys  sets a high standard in the 3D printing industry. Parts printed using Stratasys FDM can achieve an impressive accuracy of ± .127 mm (± .005 in.), making it one of the 3D printers with the highest tolerances available on the market. This level of precision is particularly advantageous for applications that require extremely tight tolerances, such as aerospace components, medical devices, and complex engineering prototypes.

In contrast, Fused Filament Fabrication (FFF) printers are often more suitable for projects that need prototypes primarily for form and visual validation, rather than for functional or load-bearing applications. These FFF printers generally struggle to maintain the consistent tolerances that are achievable with a FDM machine.

The high level of accuracy in the Fortus 450 can make a significant difference in the final product's performance and reliability. While not everyone may need parts with such high tolerances or mechanical properties, understanding this capability is crucial for those who do. It allows engineers and designers to create components that meet stringent industry standards, potentially cutting down on material waste and streamlining the research and development process.

So, if you're involved in projects that demand the utmost precision, the Fortus 450's exceptional accuracy makes it a compelling choice, separating it from other, less capable 3D printing technologies.

Fortus 450 Build Chamber

Inside the Fortus 450 Printer by Stratasys

Better Layer Adhesion

In Fused Deposition Modeling (FDM), the deposition process takes place within a specialized print chamber maintained at specific temperatures—around 90ºC for ABS or even higher for more advanced materials. This chamber is fully isolated from the surrounding environment, enabling a smooth transition for the filament as it flows from a hot extruder—usually heated to about 320ºC—through a heated environment, and finally onto a hot build platform. This hot-to-hot transition significantly enhances the mechanical properties of the printed part, notably improving layer-to-layer adhesion strength while also preventing undesirable effects like warping and curling during the filament deposition process.

In contrast, Fused Filament Fabrication (FFF) printers lack a heated chamber. Consequently, the filament moves from a hot extruder through a cold or unevenly heated ambient environment before landing on a hot build platform. This hot-to-cold-to-hot transition generates residual stresses in the printed part, impacting the part's overall quality and performance. These stresses stem from the rapid cooling of the plastic as it leaves the extruder, adversely affecting both mechanical properties and dimensional tolerances.

It's worth noting that the absence of heated chambers in FFF printers is not merely a design choice but a legal limitation due to a patent owned by Stratasys on thermal separation between the heated build chamber and the gantry controlling motion. In Stratasys' FDM printers like the Fortus 450, the motors are situated outside the enclosed chamber, ensuring a uniformly heated environment. Conversely, FFF printers often rely on heated beds to somewhat elevate the chamber's ambient temperature and improve bed adhesion. However, this workaround is far from perfect. The uneven cooling often results in unpredictable tolerances and surface defects.

This thermal inconsistency also restricts the types of plastics that can be effectively printed on FFF machines. While materials like PETG and PLA are popular choices due to their minimal shrinkage, most advanced materials pose significant challenges for anything less than an FDM machine like the Fortus 450. The precision temperature control in FDM printers opens the door to a wider range of materials, offering greater versatility for industrial applications.

Fortus 450 Gantry

Top View of a Fortus 450MC Printer

Better Quality Control

Fused Deposition Modeling (FDM) can print using some of the most robust and durable plastic materials available in the commercial market, including Polycarbonate, Nylon, ULTEM, and PEEK. The capability to use these advanced materials is largely due to FDM's enclosed oven-like chambers and strict quality control measures in the filament manufacturing process. Unlike generic, hobbyist-level filaments, those designed for FDM printers adhere to stringent ISO guidelines for quality and traceability. This ensures that the filament maintains a consistent diameter and cross-sectional area throughout its length, which is crucial for accurate and reliable 3D printing.

If you were to examine a stretch of quality FDM filament, its cross-section should ideally remain a circle. Any deviation, such as changing to an oval shape, would affect the rate of material extrusion. This, in turn, can lead to inconsistencies in surface quality, mechanical properties, and overall part accuracy. It's precisely these kinds of inconsistencies that FDM's rigorous manufacturing standards seek to eliminate.

On the other hand, lower-cost filaments designed for Fused Filament Fabrication (FFF) 3D printers often sacrifice this consistency for the sake of affordability. The trade-off here is a variable cross-sectional area, owing to looser manufacturing standards. While FDM filament manufacturers often employ laser-based quality control systems to monitor and maintain the correct diameter, the quality assurance measures for FFF filaments tend to be much less rigorous.

In FDM filament manufacturing, the use of a laser in the quality control process ensures that the filament diameter is monitored in real-time, allowing for immediate adjustments to be made during production. This level of scrutiny results in a higher cost per spool of filament but provides the user with peace of mind regarding the filament's quality and the resulting printed parts' characteristics.

To summarize, while FDM filaments may come at a higher price point, the benefits they offer in terms of material strength, print quality, and reliability often make them a worthwhile investment, especially for industrial applications where the tolerances are low and the stakes are high.

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Powerful Support Materials

With Fused Deposition Modeling (FDM), the range of geometries that can be successfully 3D printed is exceptionally broad, thanks largely to the technology's dual extrusion capabilities. Unlike some 3D printing methods that struggle with complex geometries, FDM can handle intricate designs with ease. This is due to the use of specialized soluble support materials that can be quickly and easily dissolved in a heated ultrasonic tank. These support materials are engineered to work in harmony with specific thermoplastics, ensuring optimum results regardless of the oven temperature. The use of soluble supports not only facilitates the printing of complex geometries but also negates the need for manual post-processing, thereby reducing the risk of damaging the finished part.

In contrast, dual extrusion is a relatively new development in the world of Fused Filament Fabrication (FFF) 3D printers. While some FFF printers now offer the use of a water-soluble material known as PVA (polyvinyl alcohol) for supports, the technology is still in its nascent stages. PVA has been specifically designed to be compatible with PLA, a commonly used filament in FFF printing. Under the same operating conditions and temperatures required for PLA, PVA generally performs well. However, this material shows its limitations when used to support the printing of higher-temperature and more advanced materials such as ABS and Polycarbonate.

Issues like delamination, warping, and compromised surface quality become increasingly evident when PVA is used as a support for these more advanced materials. This is because PVA was not designed to withstand the higher processing temperatures, leading to inconsistencies and flaws in the final product. These limitations can hinder the use of FFF printers for applications requiring high-performance materials and tight tolerances, thereby making FDM technology a more reliable option for such demanding scenarios.

In summary, FDM's advanced dual extrusion technology and specialized support materials offer a level of flexibility and reliability that is currently unmatched by most FFF 3D printers. This makes FDM a preferred choice for those in need of high-quality, complex parts, especially in industrial and engineering applications.

FDM Support Material

Rapid soluble support materials for FDM by Stratasys

FDM vs FFF 3D printing

FFF vs FDM 3D Printing Explained

What is the Difference?

When most people think of 3D printing, they usually think about filament manufacturing Deposition Modeling (FDM) which has existed since 1988. However, it wasn't until over 20 years later that 3D printing gained traction and popularity.

In 2009 the patent on FDM 3D Printing expired, paving the way for new, lower cost 3D printers using a similar printing process called Fused Filament Fabrication (FFF). With the advent of these low cost printers, 3D printing became both tangible and accessible to everyone, making it possible for consumers to own their own 3D printer. This sparked conversations about 3D printing and its capabilities s more and more tinkerers were adding them to their home workshops which lead to a media buzz in 2014 that made 3D printing more common place.

Unbeknownst to the average consumer  - this new lower cost printing process is very different than what has been on the market for the past two decades. Early adopters of 3D printing like GE, Airbus, BMW & Ford have been using FDM 3D printing for decades as a tool for designing low volume specialized manufacturing jigs, fixtures & parts using large industrial grade additive manufacturing machinery. While this new 3D printing technology was superficially similar to FDM,  the actual results were wildly different. 

If these low cost FFF consumer printers serve as initial exposure to 3D printing for engineers, designers and other professionals there is the potential for a negative perception about 3D printing especially if they receive a part output that is not up to the mark. This may lead them to refrain from choosing 3D printing again if they find the FFF 3D printed parts have a poor quality, strength, surface finish, or are "just not there yet" as we hear commonly in the industry. Those settling for a subordinate process (FFF) are not exposed to the scope and potential of other 3D printing technologies.

The FFF 3D printing process being touted during this media buzz was actually a very simplified version of what global companies have relied on for the past two decades to fuel their manufacturing process. Consequently this led to an incongruous expectation of what FDM (and other industrial printers) can really achieve, thereby inadvertently undermining these larger industrial machines & their applications.

What Makes FDM Better than FFF?

Fused Deposition Modeling (FDM) are large enclosed machines that cater to part applications requiring high quality, engineering-grade prototypes that can withstand mechanical loads. Parts printed in FDM are capable of achieving an accuracy of ± .127 mm (± .005 in.) which is one of the highest tolerances of any 3D printer on the market. Fused Filament Fabrication (FFF) usually caters to part applications requiring prototypes for form and visual validation and are not capable of holding consistent tolerances. While not everyone may require parts with high tolerances, or mechanical properties, here we explore what makes these printers different. 

Fortus 450 Build Chamber

Inside the Fortus 450 Printer by Stratasys

The Print Chamber In FDM the deposition process is contained in a print chamber that is maintained at about 90ºC for ABS (or higher for advanced materials). This oven is completely isolated from the ambient environment allowing the filament to flow from a hot extruder of about 320ºC through a heated environment onto a hot build platform. This hot-hot-hot transition leads to better mechanical properties, significantly increases layer to layer adhesion strength and prevents warping and curling during filament deposition.
 

FFF printers have no heated chamber, and as a result the material filament traverses from a hot extruder through a cold or unevenly heated ambient environment onto a hot build platform. This transition from a hot-cold-hot medium results in the generation of residual stresses in the part being printed and makes the part output and quality very different. This difference in part output quality is due to the immediate cooling of plastic during the extrusion processes as it leaves the print head, negatively affecting both mechanical properties and tolerances.

Fused Filament Fabrication 3D printers do not have enclosed ovens because of a patent that Stratasys owns on thermal separation between the heated build chamber and a gantry that controls motion. In Stratasys FDM printers, the motors sit on the outside of the enclosed space whereas FFF printers use heated beds to increase the ambient temperature of the chamber and increase bed adhesion. This "hack" however is less that perfect, and causes uneven cooling often results in uncontrollable tolerances, and surface defects.    

This ultimately limits what plastics can be printed effectively with PETG and PLA being very popular because of its minimal shrinkage -  but outside of these materials, most advanced material is very difficult to print on anything less than a FDM machine.

Fortus 450 Gantry

Top View of a Fortus 450MC Printer

Filament Quality Control FDM is capable of printing in some of the strongest plastic materials commercially available, including Polycarbonate, Nylon, ULTEM & PEEK. This is made possible by FDM's enclosed ovens, as well as very strict quality control in their filament manufacturing process. While FDM filaments tend to cost a bit more than hobbyist filaments, there is a significant amount of strict ISO guidelines quality & traceability guidelines that these manufacturers follow. If you look at 3D printing filament head-on it should be a circle, but along a stretch of filament the cross section can change from a circle to an oval. If filament is inconsistent across its either its’ diameter or length , this will change the rate of material extrusion resulting in poor surface quality, mechanical properties & part accuracy
 

One of the trade offs made in low cost filament is consistency in cross sectional area which is often quite variable due to much lower standards of filament producing for FFF 3D Printers.  FDM filament manufacturers use a laser as part of a quality control mechanism to ensure correct diameter, whereas the quality control process for FFF filaments is often much more lax.

FDM Support Material

Rapid soluble support materials for FDM by Stratasys

Support Materials barring minimum feature size or wall thicknesses, you will rarely find a geometry impossible to 3D print with FDM due to the dual extrusion technology. FDM 3D printers always use a soluble support material that dissolves in minutes inside of a heated ultrasonic tank. This means no damage to the part and no waiting for PVC to dissolve in water. Each FDM support material is specially designed to print with a specific thermoplastic ensuring perfect results no matter what oven temperature.
 

FFF printers are only recently starting to develop dual extrusion, often using a support material called PVA which is an abbreviation for polyvinyl alcohol, a water-soluble material. This support material was specifically designed to print with PLA and generally works fairly well as it it requires the same operating conditions and temperature of PLA. However issues of delamination, warping and surface quality issues become apparent when using PVA to support higher temperature materials such as ABS, PC or other more advanced filaments.

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