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Plastics & Elastomers

3D Printing in Plastics: SLA vs FDM

Vishal Parekh – Sep 14, 2018

SLA vs FDM 3D Printing Processes3D printing, one of the seven disruptive technologies of this century, is also among the top 10 technologies that are expected to transform the coming decades. The technology finds application in several industries, such as:

 − Industrial aerospace & defence
 − Consumer products
 − Automotive parts
 − Industrial machinery
 − Healthcare, and
 − Manufacture products using polymers, ceramics and metals

However, more than 70% of the market is currently dominated by 3D printing of polymer-based materials due to the ease of process, availability of material and low cost.

To print 3D parts, various technologies have been developed till date, such as:

 − Fused Deposition Modeling (FDM)
 − Stereolithography (SLA)
 − Selective Laser Sintering (SLS)
 − Material Jetting (MJ), and Drop on Demand (DOD)
 − Direct Metal Laser Sintering (DMLS)
 − Electron Beam Melting (EBM)
 − Metal Binder Jetting, and
 − Sand Binder Jetting

Of these, FDM and SLA are the most used. SLA was developed by 3D Systems in 1986 and FDM by Stratasys in 1988. The key reason for their adoption is that they were the early entrants in the market.

Let's find out which out of the two accounts for major market share...

Comparison of FDM AND SLA 3D Printing Technology

Over time, many technologies were developed in parallel, including several incremental innovations in FDM and SLA 3D printing technology. Today, FDM and SLA remain the leader in 3D printing of plastic materials. The two have been compared below:

Material details
Base material Typical thermoplastic materials used: PLA, ABS, PETG, Nylon, PEI (ULTEM), ASA, TPU Photopolymers: Epoxy or acrylate-based resins
Material distribution method Extrusion Vat (tank, vessel)
Binding technique Heat Light (laser)
Dimensional details
Layer thickness 0.05–0.127mm 0.05–0.015 mm
Wall thickness 1 mm 5 mm
Print volume 200 x 200 x 200 mm – Desktop
1000 x 1000 x 1000 mm – Industrial
145 x 145 x 175 mm – Desktop
1500 x 750 x 550 mm – Industrial
Support Not always required (dissolvable available) Larger support required
Smallest possible detail 140 micron 250–800 micron
Printed product quality Low to medium High
Surface texture Rough (“staircase” effect) but can be polished Smooth; often shiny
Accuracy Lowest Highest
Mechanical failure Gradual deformation until fracture Almost no deformation until sudden fracture
Food compatibility Leakage due to micro-gaps Only with special resins (can be expensive)
Chemical compatibility Leakage due to micro-gaps Yet to be defined
Post processing
Object removal from bed after printing Easy Difficult
Applications Low-cost rapid prototyping; basic proof-of-concept models; low-volume production of complex end-use parts Functional prototyping; dental applications; jewellery prototyping and casting; model-making
Pros Fast; low-cost consumer machines and materials High value; high accuracy; smooth surface finish; range of functional applications
Cons Warping; misalignment of layers; shrinking of lower parts; low accuracy; low details; limited design compatibility Average build volume; sensitive to long exposure to UV light
Overall rating of the technology based on various parameters
★★★★ ★★★☆☆

From the above analysis, it is evident that FDM has more benefits over SLA and, hence, is widely used. Even from the latest market share perspective, FDM commands around 69% in the 3D printing market, whereas SLA has less than 15%.

Most used 3D Printing Technologies

A study by Wohlers Associates in 2013 revealed that around 10,000 industrial units were sold in 2013. It also showed that of the overall units sold, Stratasys, which is mainly into FDM 3D printing, had the highest market share. As per Aranca research, in 2016, of the 255,000 units estimated to have been sold that year, FDM-based 3D printers (industrial + desktop) totaled 235,000 units (Industrial + Desktop). Hence, it can be firmly concluded that currently FDM is a highly adopted 3D printing technology for both industrial and desktop units.

FDM-based 3D printers would remain the industry standard for the next few years, given the advantages the technology has over others. Also, due to the low cost (of FDM printers as well as filament material), these printers are in huge demand in schools and universities for educational and research purposes.

 » Continue reading to explore the recent developments in SLA and FDM 3D Printing technologies along with the challenges involved! 

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