What Is FDM 3D Printing?


  1. What Is FDM 3D Printing?
  2. How FDM 3D Printing Works
  3. FDM 3D Printer
  4. Filament in FDM 3D Printing
  5. How FDM Compares to Other 3D Printing Methods
  6. Final Words

Fused deposition modeling (FDM) 3D printing has become widely adopted for rapid prototyping and manufacturing applications due to its ability to quickly and efficiently produce functional models, prototypes, and parts. This article provides an overview of what FDM 3D printing is, how the process works, the key components of an FDM 3D printer, how FDM compares to other 3D printing methods, and specifics on FDM filaments. With a foundational understanding of this popular technology, readers can determine if FDM aligns with their product development needs through our 3D Printing Online Services.

What Is FDM 3D Printing?

FDM 3D printing, also referred to as fused filament fabrication (FFF), is an additive manufacturing process that creates objects by selectively depositing thermoplastic material layer by layer based on a digital 3D model. Thermoplastic polymer filament, often ABS or PLA, is unwound from a coil and supplied to an extrusion nozzle mounted to a mechanical positioning system. The nozzle precisely extrudes and deposits the molten filament onto the built platform as it traces the first layer of the model, fusing with subsequent layers until the final model is complete.

The technology was invented in the late 1980s by S. Scott Crump, founder of Stratasys, with the goal of enabling rapid and inexpensive iteration of product prototypes. FDM 3D printing is distinguished from other additive processes, such as stereolithography (SLA) and Selective Laser Sintering (SLS), by its lower system costs as well as a range of applicable thermoplastic materials. Today, FDM 3D printing is used not just for prototyping but also for manufacturing end-use parts and products across industries like aerospace, automotive, and healthcare.

FDM 3D printer

How FDM 3D Printing Works

The FDM 3D printing process involves several fundamental steps: coordinated system movement controls, precisely heated and extruded thermoplastic filament deposition, and sequential layer fusing to additively construct a 3D object.

3D Printing Software Preparation

An FDM 3D printer requires an input 3D model file prepared using CAD software or 3D scanning technology. The model file is processed through a software slicing engine, which interprets the file and calculates the toolpaths for precise extruder nozzle movements and thermoplastic material deposition. G-code instructions are then sent to the 3D printer.

Heated Thermoplastic Extrusion

Filament supplied from a spool is fed into the extrusion print head, which heats the material to a semi-liquid state. The most common filament material for FDM is ABS or PLA plastic, but other thermoplastics are sometimes used. The heated extruder nozzle precisely deposits the molten material onto the print platform called the “build plate” per the G-code toolpaths.

Layer Bonding

As the extruder nozzle deposits melted filament along toolpaths, hot thermoplastic immediately fuses and bonds with the layer beneath it. Layers fuse together quickly, ensuring part integrity. The build plate lowers with each layer height deposition, allowing the new material to bond to the top of the prior layer.

FDM 3D Printer

A basic FDM 3D printer consists of key mechanical components, including the extruder print head, filament drive gear, build platform, and motion control system. Software and electronic controllers coordinate the system.

Print Head and Filament Drive System

The extruder print head houses a heated nozzle and thermal elements that melt supplied filament. A connected drive gear pushes filament to the nozzle at a precise rate, adjusting flow for accurate deposition.

Build Platform

The build platform, or build plate, provides a flat base for the first layer of the print. The platform is mounted to a lead screw which lowers it incrementally with each new layer, allowing vertical construction of the 3D-printed object.

Positioning System

Precision x, y, and z-axis motion control is achieved using guide rails and lead screw mechanisms. Stepper motors drive the movement of the extruder print head as well as the build plate according to instructions from the machine processor and control software.

Electronics and Software

Integrated electronic components and proprietary software accept the 3D model file, calculate coordinates, and drive motor systems to position the extruder nozzle along precise toolpaths for shape construction. Thermal control sensors provide feedback signals to regulate optimal heat for clean material extrusion and layer bonding throughout the build.

Filament in FDM 3D Printing

Thermoplastic Polymer Filament Properties

Filament is the foundational material consumed in the FDM process, directly impacting mechanical properties, accuracy, surface finish, environmental resistance, and visual appearance of printed parts. ABS and PLA are the most prevalent materials, with PETG, TPU, and other technical compounds growing in popularity. With hundreds of formulation varieties now commercially available, informed filament selection is critical depending on application requirements.

Impact on Print Quality and Printer Requirements

A filament’s melt viscosity, cooling rate, coefficient of thermal expansion, and layer adhesion properties dictate extrusion behavior and interlayer bonding, influencing print quality, accuracy, and mechanical performance. Tight filament diameter consistency within +/- 0.05mm allows proper feeding through the drive gears. Some FDM printers also require filament to be round within +/- 0.07mm ovality tolerance, enabling smooth flow through the entire path to the hot end nozzle.

Key Filament Materials Comparison

ABS – The strong, durable styrene-acrylonitrile material can produce functional prototypes and finished products needing good chemical and physical property retention across temperatures. The higher extrusion temperature makes cooling more gradual, increasing layer adhesion. Higher shrinkage must be compensated for in the design.

PLA – Easy to print with sharp corners and feature detail, polylactic acid plastic derived from corn starch and sugarcane makes it popular for models, decorative art pieces, and sustainable packaging. PLA lacks UV stability for prolonged outdoor use. The low melting point of 180°C allows faster print speeds.

PETG – Modified glycol-enhanced PET offers superior layer bonding and chemical resistance with minimal warping compared to standard PLA, making it well-suited for fluid and gas transport components. Ductility is retained even below its glass transition temperature, enabling flexing without fracture.

TPU – Thermoplastic polyurethane has highly desired elasticity while retaining dimensional stability. Shore hardness values ranging from 35A to 95A allow formulation tuning, meeting needs from wearable device flexibility up to durable engineering elastomers. Support structures are often required during printing to prevent deformation.

Exotic and Composite Filaments Expand Applications

From wood and metal filled to dissolvable support, antimicrobial, UV reactive, and cartoonish color-changing filaments, ongoing materials advancements target improvements in adhesion, dimensional tolerance, aesthetics, custom mechanical properties, and sustainability. The growing material selection enables FDM to expand the production of end-use parts not previously viable.

How FDM Compares to Other 3D Printing Methods

FDM has key differences from VAT photopolymerization methods like stereolithography (SLA) and powder bed fusion techniques like selective laser sintering (SLS) – popular alternatives in the 3D printing arena. Comparison factors include materials, accuracy, post-processing, and overall operating costs, which can help match specific user application requirements to the optimal additive technology.

Material Options

FDM machines exclusively process thermoplastics like ABS, PLA, PETG, TPU with hundreds of filament varieties commercially available. Photopolymer SLA resins have limited materials but produce detailed prints. SLS offers excellent material diversity, including plastics, metals, ceramics, and sandstone.

Resolution and Accuracy

The SLA approach can achieve exceptionally smooth surface finish and fine feature detail down to 25-micron resolution vs FDM at 100-200 microns depending on print parameters. SLS accuracy falls between the two from 50 to 100 microns typically. Dimensional fidelity is influenced by a number of system and processing factors across methods.

Post-Processing Requirements

Most FDM prints can be used as produced with little post-processing aside from support structure removal. Photopolymer SLA requires final UV curing and rinse processes, while products made using SLS usually undergo media blasting and infiltration to achieve full density and desired finish.

Operating Costs

Upfront printer hardware and ongoing material costs of FDM systems make this the most economically accessible 3D printing option for the widest range of users, helping drive adoption. Operating expenses for SLA and SLS methods are markedly higher, given consumable resin vats and pricier powder materials.

Final Words

With fundamental knowledge of the fused deposition modeling 3D printing process, extruder mechanisms, build schemes, and material requirements covered here, readers are equipped to further explore specific FDM solutions matching their product design and development needs – both today and into the future as new innovations continue advancing the FDM landscape.