FDM Printing: Everything You Need to Know

Fused deposition modelling (FDM) is one of the most common methods of 3D printing. It works by selectively depositing molten thermoplastic material layer by layer to build up a 3D object.

This blog will take a closer look at how FDM printing works and its key characteristics.

What is FDM Printing and How Does It Work?

The FDM, or filament, printing process starts with a 3D digital model designed using CAD software or scanned from an existing object. This model is then converted into an STL file format that slices the model into thin layers.

The FDM printer heats up a thermoplastic filament to a semi-liquid state and extrudes it precisely through a print nozzle onto the print bed following the CAD model one layer at a time. The initially extruded material quickly solidifies and fuses with the layer below. The print head moves in both horizontal and vertical directions, depositing material onto the printable area of the build platform.

Once a layer is finished, the build platform lowers, and a new layer is deposited on top. This process continues until the entire object has been built from the bottom up. Support structures may be required during overhanging geometry builds.

In contrast, resin printers, also known as SLA (Stereolithography) or DLP (Digital Light Processing) printers, use a completely different approach.

These printers utilise a tank filled with liquid photopolymer resin, which is selectively cured (hardened) into solid form by a UV light source. This light is either directed by mirrors (in the case of SLA printers) or projected as a whole layer image (in DLP printers), solidifying the resin according to the 3D model layer by layer. 

For those interested in exploring the advantages and considerations of each technology further, check out our comparison of FDM vs resin printers. This article provides a deep dive into aspects like material cost, durability, and printing speed.

FDM Print System Parameters

There are several key parameters that influence FDM print quality, speed, and overall system performance:

• Nozzle diameter: Typical range is 0.2mm to 1mm. Fine nozzles allow more detail but slower prints.
• Layer height: Thinner layers mean more detail but slower prints. Typical range is 0.05mm to 0.3mm.  
• Build platform temperature: Heats the material to prevent warping and improve the first layer adhesion. 
• Extrusion temperature: Melts the filament material. Usually 190°C to 250°C depending on the polymer used.
• Infill: Controls interior fill density from 0% to 100%. Lower infill speeds print time. 
• Print speed: The speed the machine head moves during deposition, typically 30-200 mm/sec.

Differences Between Desktop and Industrial FDM Printers

There are distinct differences between lower-cost desktop machines and high-end industrial FDM printers:

• Build volume: Industrial systems can print extremely large objects over 1 cubic meter. 
• Material capabilities: Industrial printers can utilise high-temp and advanced polymers like PEEK, ULTEM or polycarbonate. Desktop units usually only print PLA and ABS. 
• Part accuracy and repeatability: Industrial printers use rigid metal frames resulting in precision down to ~0.1mm vs. ~0.5mm 
• Build chamber temperature control: Industrial chambers regulate temperatures up to over 300°C for speciality plastics. Most desktop devices print in ambient room temperatures.
• Production speed: Industrial systems are faster with extrusion rates over 200 cubic cm per hour, ideal for mass manufacturing. Desktop devices max out at 20-100 cm3/hour.
• Connectivity: Industrial printers often include onboard cameras for remote monitoring and network connections for printing direct from digital files vs. desktops that print from SD cards or USB sticks.

What Are the Characteristics of FDM Printing?

FDM printing technology offers economical production solutions with several appealing advantages. 

Both the printers themselves and the filament materials have become very affordable, with models like the TRILAB DELTIQ 2 3D PRINTER and the TRILAB DELTIQ 2 PLUS 3D Printer available for less than £4,000.

The process also generates much less material waste compared to methods like CNC machining which can waste 90% or more of raw material removed during shaping. FDM printers don't require installing any special ventilation or facilities, even larger ones like the ZMORPH I500 LARGE-FORMAT ~460MM * DUAL HEAD or the VSHAPER 5AXMACHINE.

There is also a growing range of over a dozen thermoplastic materials to choose from including lower-cost PLA and ABS as well as advanced polymers like PETG and composites. Furthermore, leftover print material like rafts and supports can simply be recycled and re-extruded into fresh filament, greatly reducing total waste. 

Taken together, these FDM capabilities provide accessible and practical 3D printing with low upfront and ongoing expenses.

Drawbacks include lower accuracy and strength compared to industrial AM processes like selective laser sintering (SLS) or stereolithography (SLA). The layered stepped look of FDM prints also requires more finishing work vs. other technologies.

Common Materials for FDM Printing

The most popular FDM print materials are:

• PLA (Polylactic acid) - Made from plant-based sources like corn starch. Inexpensive, easier to print than ABS and used for concept models.
• ABS (Acrylonitrile butadiene styrene) - Stronger than PLA. Used to print durable parts and prototypes, although it can be prone to warping.
• PETG (Polyethylene terephthalate glycol-modified) - Combines the strength of ABS with easier printing like PLA. Most common material for final-use parts.
• TPU (Thermoplastic polyurethane) - A flexible rubber-like material used for elastic components that bend or compress.

The Pros and Cons of FDM 3D Printing

FDM printing offers several key advantages that make it appealing for various applications. First, the materials and equipment cost is relatively low, which makes it suitable even for small budgets. For example, the TRILAB AzteQ Industrial 3D Printer is available for less than £8,000.

Second, it does not require special ventilation in the workshop compared to technologies like SLA. There is also a range of different materials with different properties to suit different applications from rigid to flexible. 

Finally, FDM is a very well-established technology with a large community support base for troubleshooting, software tools, and new material development to enable further innovation.

FDM does have some disadvantages to consider as well. First, the resolution and accuracy are lower compared to other 3D printing methods like stereolithography (SLA) and selective laser sintering (SLS). Second, the visible horizontal layer lines inherent in the process can negatively impact both appearance as well as part strength. Third, there are size limitations on prints based on the build volume of the specific 3D printer being used. 

In addition, support material may be required during the printing process for some geometries, which must later be removed and can impact the surface finish. Despite these cons, FDM remains a versatile and accessible technology for a wide range of applications.

FDM strikes an excellent balance of affordability, ease of use and material versatility. It enables rapid prototyping of designs during product development as well as ongoing production of final parts, making it the backbone of industrial and desktop 3D printing.

If you have any questions about our excellent range of FDM printers, feel fre call us on 0800 689 0719 or contact us via form.