What is FDM Printing? | The Ultimate Guide

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what is FDM printing

What is FDM Printing?

FDM printing, or Fused Depositing Modelling, is an additive manufacturing or 3D printing process belonging to the material extrusion family. In this technique, materials are fused or combined in a pattern to create an object. It uses thermoplastic polymers like ABS (acrylonitrile-butadiene-styrene) and PLA (polylactide acid) in filament form. The thermoplastic resin is melted just past its glass transition temperature. In FDM, a part is produced by depositing material in a pre-determined pattern layer-by-layer.

FDM printers are the most common 3D printers in terms of availability and usage; it is often the first 3D technology device most manufacturers are exposed to. This is because of its inexpensiveness and efficiency.

How does FDM Printing work?

Let’s go through the FDM modeling process.

  1. First, the nozzle is heated to the desired temperature; then, the filament will be poured inside the printer. Finally, the filament will be filled in the nozzle where it melts and extrusion head.
  2. The extrusion head will move in X, Y, and Z directions as it is fixed with a 3-axis system. Finally, the molten material will be extruded in thin strand-like structures and settled layer-by-layer in predetermined locations properly.
  3. Multiple passes will be required to fill an area. When a layer is completed, the build platform moves downwards, or the extrusion head will upwards(depending on the machine setup), and a new layer has been settled. A similar process will repeat itself until the part is made.

Attributes of FDM 

Attributes of FDM

Printer Guidelines

Several FDM machines allow modifications with certain process parameters. Changes are constantly seen in the nozzle and build platform temperature, layer height, build speed, and even cooling fan speed. The changes are made b a trained operator, so it shouldn’t worry designers.

The general desktop printers are sized 200 x 200 x 200 mm, while for industrial machines, this can be as big as 1000 x 1000 x 1000 mm. Desktop machines are favored for cost-saving, and industrial FDM printers are preferred when multiple smaller parts are made, which later will be assembled to create something bigger in size.

The typical layer’s height ranges from 50 microns to 400 microns. Sammler layer height is better at pricing smoother components with better-curved geometries. Talking about the larger layer heights, they are hand for producing in bulk, consuming less time.

Warpage

Warpage is a common defect in the whole plastic processing industry, let alone fused depositing modeling. When expelled material is cooled for solidification, its dimension decrease, and different sides of the component cool at different speeds. Dissimilar cooling triggers internal stresses that push the underlying region upwards, causing an unusual bend called warpage.

The prime solution to look after the warpage is to monitor the temperature variations of the FDM machine properly and increase the fixing of the component with the build platform.

Layer Adhesion

For maintaining an FDM part’s quality and integrity, adhesion is crucial between the deposited layers. When the molten material is expelled through the nozzle, it is deposited against the previous layer. The surface of the previous layer re-melts because of high temperature and pressure.

Interesting Fact – The bond strength between the layers is always greater than the material’s base strength.

The above fact shows that FDM parts hold most of their strength in the XY plane, and the Z-axis is weaker. Thus, taking care of part orientation is significant n FDM printing.

Having said that, since the molten thermoplastic is caressed against the previous layer, its sea becomes similar to an oval. This means that the FDM component will always have a zigzag or kinked surface, and small holes and heard might need post-processing.

Support Structure

Support structure comes in handy for creating shapes with overhangs in FDM 3D printing. The molten material cannot be depicted that easily. That’s why some complications happen and might need a support structure.

Support structures are advantageous, but they can lead to compromise on the surface quality. For that reason, it is advised to design the part in a manner that doesn’t require any support.

Infill & Shell Thickness

Unlike other 3D printing methods, FDM components are not printed solid to reduce costs and time. Instead, the outer layer is traced using a shell (a reliable pass), and the internal is loaded with infill (a low-density structure). The strength of a component is highly dependent on shell thickness and infill.

For adequate strength and good speed with FDM prints, the infill density default setting should be 25% and 1 mm shell thickness.

Interesting Read – 6 Best Plastic Molding Techniques | A Complete Analysis

Design Variations and Guidelines 

There are several variations made with fused deposited modeling printers to achieve certain types of results. These include:

  1. Filament extruders or expellers are extensively used as a variation for utilizing reels of thermoplastic filaments.
  2. Pellet extruders for exchanging the filament for granules of plastic.
  3. Paste extruders are used to expel paste, common uses being in food and ceramic.
  4. Chocolate extruders(the nicest thing in the world:)) often used for extruding the desired shape of chocolate.

The common aspect within all the variations is that the material is extruded through a nozzle onto a build plate.

The main design guidelines one must follow for optimal are shown in the below table.

FDM Characteristics
Regular layer height
50 to 400 microns
Thermoplastic Materials
ABS, PETG, PEI, PLA, PC
Typical build size
Desktop – 200 x 200 x 200 mm, Industrial – 1000 x 1000 x 1000 mm
Dimensional accuracy
Desktop – 0.5% (lower limit ± 0.5 mm), industrial – 0.15% (lower limit ± 0.2 mm)
Support
Required sometimes

Advantages and Disadvantages 

fdm advantages and disadvantages

Advantages

  • The most prominent advantage provided by FDM 3D printing is scalability. Scaling it to size is a relatively easy task. All one needs to do is make the gantry rails longer, making the build area larger.
  • FDM printers are cost-effective and abundantly available compared to other 3D printing machines. The reason for that low part cost and involvement in single designs.
  • Compatibility with a variety of thermoplastic materials and filaments. Desired parts can make with relatively smaller upgrades and modifications.
  • The lead times are short. Parts are delivered on short notice (as quick as 1-day delivery)
  • FDM printing leads to rapid transfer of multimedia data with very high efficiency and low noise and distortion.

Disadvantages

  • The layer adhesion mechanism makes FDM parts naturally anisotropic.
  • Achieving parts with a smooth finishing and professional-looking aesthetic is a challenging task in FDM printing. The problem is the material must be extruded in layers and has a certain thickness pre-set by the nozzle. Thus high precise and professional look needs several post-processing activities.
  • The visible layer lines can also hurt the integrity of the product (although it’s not that serious), which will also need post-processing.

The Best FDM Materials 

Attributes of FDM

As mentioned in the advantages, one of the main benefits of FDM 3D printing is the wide choice of materials. It is compatible with engineering materials like TPU, Nylon, and PETG – commodity thermoplastic like ABS and PLA, and high-performance thermoplastics such as PEEK and PEI.

The used material will determine the mechanical properties, and many other characteristics of the FDM printed parts, like cost, integrity, application, etc. There is a table below that shows the attributes of the materials.

Fascinating Read – What is Acrylic Plastic? | How is Acrylic made | Acrylic Grades and Applications | Advantages & Disadvantages

Material Drawback(s) Limitation
TPU Very flexible
accurate printing is difficult
ABS Great strength and temperature resistance
Susceptible to warping
PLA Fantastic visual quality, easy processibility
Low-impact strength
PETG Easy processibility, decent strength, food-safe –
Nylon Fantastic wear and chemical resistance, high-strength
weak humidity resistance
PEI Great strength to weight ratio, fantastic fire, and chemical resistance high-cost

FDM Printing Applications 

FDM Applications

  • Prototypes
  • Gifts
  • Architecture 
  • Prosthetics 
  • Industrial Applications 

1. Prototypes

The most common and popular application for FDM remains to prototype. Prototyping newer and innovative products become easier through FDM thanks to its low cost and easy setup.

2. Gifts

The gifting industry is constantly evolving, with people’s tastes, habits, and lifestyles changing so rapidly these days. So hobbyists and enthusiasts highly utilize For constantly developing innovative, stylish, intricate products quickly according to customers’ needs.

FDM machines are affordable solutions for the rapidly evolving and changing gifting industry.

3. Prosthetics

It can be extremely beneficial for producing low-cost, lightweight, strong, and flexible prosthetics replacing older and heavier variations that are extremely uncomfortable for patients with serious health issues.

Prosthetic arms and legs are the most common applications suitable for both kids and adults.

4. Industrial Applications

FDM parts are commonly used in medical, automotive, aerospace, and manufacturing applications. It’s a common misconception that FDM parts can only be used in low-end applications, but that’s not true. Industrial FDM printers are capable of strong, rigid, and functional parts for high-end industrial use.

Engaging Read – What is Rotational Molding | Rotational Molding Process | Advantages & Disadvantages | Best Material for Rotational Molding

Mega Comparison: FDM Vs. SLS Vs. SLA

Differences
Factors FDM SLS SLA
Print Volume Up to ~200 x 200 x 300 mm (desktop 3D printers) 300 x 300 x 300 mm (up to 750 x 550 x 550 mm)
Up to 300 x 335 x 200 mm (desktop and benchtop 3D printers)
Compatible Materials
Thermoplastics like ABS, PLA, PEEK, TPU, Nylon, etc
 Nylon, and sometimes PEEK
Most common – Nylon and its various blends, sometime PEEK is also used
Pros Low-cost machine, materisl and overall set-up, No need for the support structure, parts with good mechanical properties, parts with more complex geometries
high accuracy, range of functional applications, smooth and cleaners surface finish
Cons Low accuracy, low design range, low details, visible layer lines no desktop size printing version, grainy surface finish
Sensitive to prolonged exposure to UV light
Dimensional accuracy desktop – ± 0.5% (lower limit ± 0.5 mm), Industrial – 0.15% (lower limit ± 0.2 mm) ± 0.3% (lower limit of ± 0.3 mm)
± 0.5% (lower limit: ± 0.010 – 0.250 mm)
Typical build size desktop – 200 x 200 x 200 mm, industrial – 1000 x 1000 x 1000 mm 300 x 300 x 300 mm (up to 750 x 550 x 550 mm)
Up to 145 x 145 x 175 mm
Applications Basic proof of concept models, rapid prototyping, medical, dental, rapid prototyping, architecture, etc.
patterns, molds, tooling, functional prototyping, casting, dental applications, etc

The History of FDM 3D Printing

Fused deposit modeling technology was first conceptualized and created by Scott and Lisa crump, the founders of Stratasys, in 1988. Crump came up with the idea to build a toy frog for her daughter using a glue gun, a mixture of polyethylene, and candle wax. In 1989, Crum patented the FDM technology and founded Stratasys. The company became the pioneer of 3D printing technology, providing the best quality 3D printers and materials.

Stratasys made a software process that converts stereolithography (STL) files into another format to slice sections of the 3D model and decides how the layers will be printed.

FAQs 

1. Which one is stronger: SLA or FDM?

Ans. In terms of material strength and mechanical performance, SLA resins have no chance compared to FDM filaments. FDM materials like Nylon and polycarbonate are known for their toughness and rigidity. SLA resins generally are more expensive and yield fewer parts per unit of resin than FDM 3D printing filament spools.

2. What is the most accurate FDM 3D printer?

Ans. Talking about accuracy and also keeping in mind the cost-effectiveness, the best options are:

  1. Raise3D Pro 2 – Plug and Play 3D Printer
  2. Ultimaker 3 – Dual printing cores
  3. Tronxy X5SA Pro – Cost-effectiveness
  4. Lulzbot Taz Workhorse – Oustanding accuracy
  5. Original Prusa i3 MK3S – Premium Pick

3. Why Guard bands are used in FDM?

Ans. In FDM, several signals are transferred at the same time on the same channels allocating separate frequency bands to each signal. Guard bands are used to avoid hindrance between two successive channels.

4. Who are the top 3D printing companies?

Ans. The top 5 3D Printing companies are:

  1. 3D Systems Corp. (DDD)
  2. Proto Labs Inc. (PRLB)
  3. FARO Technologies Inc. (FARO)
  4. Materialize NV (MTLS)
  5. The ExOne Co. (XONE)

5. What are the common problems practicing while 3D printing? 

Ans. Here are some persistent problems faced while 3D printing:

  1. Under-Extrusion
  2. Over-Extrusion
  3. Gaps in the top layers
  4. Over-Heating
  5. Layer shifting
  6. Not sticking to the bed
  7. The printer is extruding the plastic at the beginning of the print.

Suggested Read – 

Final Thoughts 

That is all from my side for FDM printing. This additive manufacturing technique is hugely popular among manufacturers for easy availability and inexpensiveness. So, if you’re a beginner or an aspiring engineer, or a bootstrapped startup owner, then Fused deposit modeling is a boon for you.

I hope you liked my piece. Keep reading, and kindly comment on your reviews in the comment box.

Have a lovely day

Peace Out.

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