What is the Difference Between SLA and FDM Printers?

Are you trying to figure out whether to go with SLA or FDM printers for your next project? As a 3D printing parts manufacturer, we know the world of 3D printing can be overwhelming with so many options, but making the right choice doesn’t have to be hard. Both SLA (Stereolithography) and FDM (Fused Deposition Modeling) have their own strengths, suited for different needs. Picture creating detailed, high-precision prototypes with SLA, or producing strong, functional parts quickly and affordably with FDM. Getting to know these technologies can really help you get the most out of your project. Let’s dive into what makes SLA and FDM printers tick, and see which one fits your goals best. We’ll break down their processes, materials, and uses so you can make a smart choice that boosts your creativity and productivity. Ready to take your 3D printing to the next level? Let’s explore the key differences between SLA and FDM printers together.


What is 3D Printing?

3D printing, also known as additive manufacturing, involves creating three-dimensional objects from digital files by layering materials sequentially. This technology has revolutionized prototyping and manufacturing, allowing for rapid production of complex geometries that would be difficult or impossible to achieve with traditional methods.

What is SLA (Stereolithography)?

Stereolithography (SLA) is one of the earliest 3D printing technologies, invented in the 1980s by Charles Hull. It uses a laser to cure liquid resin into hardened plastic in a layer-by-layer process, creating highly detailed and accurate parts.

How SLA Printers Work

SLA printers operate by using a UV laser to selectively cure liquid photopolymer resin. The process begins with a build platform submerged in a vat of resin. The laser traces a pattern on the resin’s surface, solidifying it. The platform then lowers slightly, and the process repeats, building the object layer by layer.

Photopolymerization Process

Photopolymerization is the chemical process by which the liquid resin hardens when exposed to UV light. This process allows for high precision and fine details, making SLA ideal for applications requiring smooth surfaces and intricate designs.

Layer Curing with UV Light

Each layer is cured by the UV laser, which solidifies the resin in precise patterns. This meticulous layer-by-layer curing process results in parts with excellent resolution and surface finish.

Common Materials Used in SLA

SLA primarily uses photopolymer resins, which come in various formulations to meet different needs.

Resins: Standard, Engineering, Biocompatible

Standard resins are used for general-purpose applications, while engineering resins offer enhanced mechanical properties for more demanding uses. Biocompatible resins are suitable for medical and dental applications, ensuring safety and compatibility with the human body.

sla 3d printing

What is FDM (Fused Deposition Modeling)?

Fused Deposition Modeling (FDM) is another well-established 3D printing technology, developed by Scott Crump in the late 1980s. FDM builds objects by extruding melted thermoplastic filament through a heated nozzle, layer by layer.

How FDM Printers Work

FDM printers work by feeding a thermoplastic filament into a heated extruder. The extruder melts the filament and deposits it onto the build platform, where it cools and solidifies. The platform moves down incrementally as each new layer is added.

Extrusion Process

The extrusion process involves heating the filament until it becomes semi-liquid, then precisely depositing it through the nozzle. This process continues layer by layer until the entire object is built.

Layer-by-Layer Deposition

FDM’s layer-by-layer deposition method is less precise than SLA but offers significant advantages in terms of material strength and durability. Each layer adheres to the previous one, creating a solid and robust structure.

Common Materials Used in FDM

FDM printers use a variety of thermoplastic filaments, each suited to different applications.

Filaments: PLA, ABS, PETG, and More

PLA (Polylactic Acid) is a popular, biodegradable material ideal for beginners and general-purpose printing. ABS (Acrylonitrile Butadiene Styrene) offers greater strength and temperature resistance, making it suitable for functional parts. PETG (Polyethylene Terephthalate Glycol) combines the ease of PLA with the strength of ABS, offering durability and flexibility.

PolyJet 3d printing

Table Comparing SLA and FDM Printers

Category SLA (Stereolithography) FDM (Fused Deposition Modeling)
Printing Process Uses a UV laser to cure liquid resin into hardened plastic, layer by layer. Extrudes melted thermoplastic filament through a heated nozzle, depositing it layer by layer.
Precision and Resolution High precision with smooth surfaces; layer heights as small as 25 microns. Good detail, but visible layer lines; typical layer heights between 50 and 200 microns.
Materials Photopolymer resins (standard, engineering, biocompatible). Thermoplastic filaments (PLA, ABS, PETG, and more).
Print Quality Excellent surface finish and fine details. Strong parts but with visible layer lines that may require post-processing.
Speed and Efficiency Generally slower due to the meticulous curing process for each layer. Faster printing, especially for larger parts.
Material Strength SLA resins can be brittle but offer high precision. FDM filaments, particularly engineering-grade materials, provide greater strength and durability.
Material Costs More expensive due to specialized properties and higher production costs. More affordable and widely available.
Post-Processing Requires thorough cleaning and additional UV curing; common techniques include sanding, polishing, and painting. Requires removal of support structures and smoothing of layers; techniques include sanding, chemical smoothing, and coating.
Best Uses High-detail prototypes, medical models, jewelry, and miniatures. Functional prototypes, large-scale models, educational and hobbyist projects.
Initial Investment Higher cost due to advanced technology and precision, though prices are decreasing. Generally more affordable.
Operating Costs Higher due to the cost of resins and maintenance needs. Lower due to cheaper filament and less intensive maintenance.
Ease of Use More complex due to resin handling and post-processing. Easier to use with a shorter learning curve, making it suitable for beginners.
Maintenance Requires frequent cleaning of the resin tank and laser optics. Regular nozzle and bed maintenance are necessary.
Environmental Impact Generates waste in the form of excess resin and support structures; higher energy usage due to UV curing. Produces waste filament and failed prints; more energy-efficient.
Recycling Options Limited recycling options; some resins can be recycled but vary by type. More options for recycling; PLA is biodegradable, making it a more environmentally friendly choice.
Energy Consumption Higher due to the UV curing process. Lower energy consumption during the printing phase.
Common Applications High-detail prototypes, medical and dental applications, intricate jewelry designs, detailed miniatures. Functional prototypes, large-scale models, educational and hobbyist projects, and parts requiring robust mechanical properties.


Both SLA and FDM have unique strengths and weaknesses. SLA excels in detail and precision, while FDM offers strength and affordability. Understanding these differences helps in making an informed choice.

Factors to consider include the specific needs of your project, budget, and desired material properties. By weighing these factors, you can select the printer that best meets your requirements.

Final Thoughts on Selecting the Best Printer for Your Needs

Choosing between SLA and FDM depends on your project goals. Whether you need high-detail prototypes or robust functional parts, understanding the capabilities of each technology will guide you to the right decision for your 3D printing needs.

Since 2005, Modo Rapid has been providing top-notch 3D printing services. Ready to bring your project to life?

Send us your drawings to get a quote and discover how we can help you achieve your goals with precision and efficiency.