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Stereolithography (SLA) 3D Printing Service

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→ Why SLA 3D Printing?

Stereolithography (SLA) is an industrial 3D printing process used to create concept models, cosmetic prototypes, and complex parts with intricate geometries in as fast as 1 day. A wide selection of materials, extremely high feature resolutions, and quality surface finishes are possible with SLA.

SLA 3D printing is primarily used for:

  • parts requiring high accuracy and features as small as 0.002 in.
  • good surface quality for cosmetic prototypes
  • form and fit testing

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3D Printing Surface Finish Guide

Get this quick reference guide to explore your surface finish options across our six 3D printing technologies.

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SLA Design Guidelines and Capabilities

Our basic guidelines for stereolithography include important design considerations to help improve part manufacturability, enhance cosmetic appearance, and reduce overall production time.


SLA Tolerances

For well-designed parts, tolerances in the X/Y dimension of ±0.002 in. (0.05mm) for first inch plus 0.1% of nominal length. (0.001mm/mm), and Z dimension tolerances of ±0.005 in. for first inch plus 0.1% of nominal length, can typically be achieved. Note that tolerances may change depending on part geometry.

Max Part Size

Layer Thickness

Minimum Feature Size

Minimum Wall Thickness

Minimum Hole Size

Tolerances

*Available for the following materials: ABS-Like White and Gray, ABS-Like Translucent/Clear, and PC-Like Translucent/Clear

SLA Material Options

ABS-Like White (Accura Xtreme White 200)

ABS-Like White (Accura Xtreme White 200) is a widely used general purpose SLA material. In terms of flexibility and strength, this material falls between molded polypropylene and molded ABS, which makes it a good choice for functional prototypes. Parts as large as 29 in. x 25 in. x 21 in. can be built with ABS-Like White so consider it a primary option if you require an extensive part size build envelope.

Primary Benefits

  • Durable, general purpose resin
  • Accommodates extra-large parts

ABS-Like Gray (Accura Xtreme Gray)

ABS-Like Gray (Accura Xtreme Gray) is a widely used general purpose SLA material. In terms of flexibility and strength, this material falls between molded polypropylene and molded ABS, which makes it a good choice for functional prototypes. ABS-Like Gray offers the highest HDT of the ABS-like SLA resins.

Primary Benefits

  • Durable, general purpose resin
  • Highest HDT of the ABS-like SLA resins

ABS-Like Black (Accura 7820)

ABS-Like Black (Accura 7820) is a widely used general purpose material. Its deep black color and glossy up-facing surfaces in a top profile offer the appearance of a molded part, while layer lines may be visible in a side profile. RenShape 7820 also has low moisture absorption (0.25% per ASTM D570) so that parts are more dimensionally stable. Compared to other SLA materials, it has midrange values for all mechanical properties.

Primary Benefits

  • Low moisture absorption
  • Glossy cosmetic appearance

ABS-Like Translucent/Clear (WaterShed XC 11122)

ABS-Like Translucent/Clear (WaterShed XC 11122) offers a unique combination of low moisture absorption (0.35% 0.25% per ASTM D570) and near-colorless transparency. Secondary operations are required to achieve functional part clarity, and the part will also retain a very light blue hue afterward. While good for general-purpose applications, WaterShed is the best choice for flow-visualization models, light pipes, and lenses.

Primary Benefits

  • Lowest moisture absorption of SLA resins
  • Functional transparency

MicroFine™ (Gray and Green)

MicroFine™ is a custom formulated material available in gray and green that is exclusive to Protolabs. This ABS-like thermoset is printed in Protolabs’ customized machinery to achieve high resolution features as small as 0.002 in. MicroFine is ideal for small parts, generally less than 1 in. by 1 in. by 1 in. In terms of mechanical properties, MicroFine falls in the mid-range of SLA materials for tensile strength and modulus and on the low end for impact strength and elongation.

Primary Benefits

  • Produces highest resolution parts
  • Ideal for extra-small parts

PP-Like Translucent White (Somos 9120)

PP-Like Translucent White (Somos 9120) is the most flexible SLA option outside of Carbon RPU 70 and FPU 50. In direct comparison to the average values of an injection-molded polypropylene, 9120 has similar tensile strength, tensile modulus, flexural modulus, and impact strength. The only departure from molded PP is its elongation value, which is only 25% of the molded thermoplastic.

Primary Benefits

  • Semi-flexible
  • Translucency

PC-Like Advanced High Temp (Accura 5530)

PC-Like Advanced High Temp (Accura 5530) creates strong, stiff parts with high temperature resistance. A thermal post-cure option can increase HDT as high as 482°F at 0.46 MPa loading. Accura 5530 has the highest E-modulus of all the unfilled SLA materials, and it is known for being resistant to automotive fluids. However, the thermal curing process does make Accura 5530 less durable, resulting in a 50% reduction to elongation.

Primary Benefits

  • High elastic modulus
  • Higher resistance to heated fluids

PC-Like Translucent/Clear (Accura 60)

PC-Like Translucent/Clear (Accura 60) is an alternative to the general purpose ABS-like materials and WaterShed XC 11122 when stiffness is desired. Like WaterShed, this material can be custom finished to achieve functional transparency with secondary processing. Accura 60 has the highest tensile strength of and elastic modulus compared of all SLA materials outside of the Advanced High Temp options that are most often thermal cured.

Primary Benefits

  • High stiffness
  • Functional transparency

Ceramic-Like Advanced HighTemp (PerFORM)

Ceramic-Like Advanced HighTemp (PerFORM) exhibits the highest tensile strength and E-modulus making it the stiffest performance material of the SLA materials. When the thermal cure option is applied to parts made from PerFORM, it exhibits the highest HDT (as high as 514°F at 0.46 MPa loading) of the SLA materials.

Primary Benefits

  • Stiffest SLA resin
  • Highest HDT of SLA resins

Compare SLA Material Properties

  • US
  • Metric

Material  Color  Tensile Strength Tensile Modulus Elongation
ABS-Like White
(Accura Xtreme White 200)		 White 7.9 ksi 479 ksi 9%
ABS-Like Gray
(Accura Xtreme Gray)		 Gray 5.8 ksi 290 ksi 9%
ABS-Like Black
(Accura 7820)		 Black 7.0 ksi 435 ksi 5%
ABS-Like Translucent/Clear (WaterShed XC 11122) Translucent/Clear 7. 9 ksi 421 ksi 6%
MicroFine™
(Gray and Green)		 Gray or Green 8.7 ksi 377 ksi 8%
PP-Like Translucent White (Somos 9120) Translucent/White 5.0 ksi 232 ksi 25%
PC-Like Translucent/Clear (Accura 60) Translucent/Clear 10.8 ksi 508 ksi 7%
PC-Like Advanced High Temp* (Accura 5530)  Translucent/Amber 6.5 ksi 566 ksi 1.5%
Ceramic-Like Advanced HighTemp*
(PerFORM)		 White 10.9 ksi 1523 ksi 1%

*Properties listed are based on thermal cure

Material  Color  Tensile Strength Tensile Modulus Elongation
ABS-Like White
(Accura Xtreme White 200)		 White 54.47 Mpa 3300 Mpa 9%
ABS-Like Gray
(Accura Xtreme Gray)		 Gray 39. 98 Mpa 2000 Mpa 9%
ABS-Like Black
(RenShape SL7820)		 Black 48.26 Mpa 3000 Mpa 5%
ABS-Like Translucent/Clear (WaterShed XC 11122) Translucent/Clear 54.47 Mpa 2600 Mpa 6%
MicroFine™
(Gray and Green)		 Gray or Green 59.98 Mpa 2600 Mpa 8%
PP-Like Translucent White (Somos 9120) Translucent/White 34.47 Mpa 1600 Mpa 25%
PC-Like Translucent/Clear (Accura 60) Translucent/Clear 74.46 Mpa 3503 Mpa 7%
PC-Like Advanced High Temp* (Accura 5530)  Translucent/Amber 44.81 Mpa 3902 Mpa 1.5%
Ceramic-Like Advanced HighTemp*
(PerFORM)		 White 75.15 Mpa 10,500 Mpa 1%

*Properties listed are based on thermal cure

These figures are approximate and dependent on a number of factors, including but not limited to, machine and process parameters. The information provided is therefore not binding and not deemed to be certified. When performance is critical, also consider independent lab testing of additive materials or final parts.

Surface Finish Options for SLA Parts

Material: ABS-like Translucent/Clear
Finish: Unfinished

Material: MicroFine Gray™
Finish: Unfinished

Material: ABS-like Translucent/Clear
Finish: Standard

Material: MicroFine Gray™ 
Finish: Standard

Material: ABS-like Translucent/Clear
Finish: Natural

Material: MicroFine Gray™ 
Finish: Natural

Material: ABS-like Translucent/Clear
Finish: Custom

Material: MicroFine Gray™ 
Finish: Custom

Additional Finishing Options

Custom finishing is a mix of science, technology, and fine art that can transform a part to your exact specifications. Finishes include:

  • Soft-touch paint
  • Clear part finishing
  • Paint finishes
  • Masking
  • Color matching
  • Decals/graphic
  • Texture

Metal Plating

Our metal-plating process for SLA coats a ceramic-filled PC-like material (Somos PerFORM) with a nickel that gives parts the look, feel, and strength of metal, but without the weight. The combination of the material’s strength, rigidity, and temperature resistance with nickel plating, takes strength, stiffness, and impact and temperature resistance to a degree previously unattainable in SLA parts.

Microfluidics

Our microfluidic fabrication process is a modified form of high-resolution SLA that uses a clear ABS-like material (WaterShed XC 11122). Parts are resistance to water and humidity, and work well for lens and flow-visualization models.

Our SLA 3D Printers

Our stereolithography machines consists of Vipers, ProJets, and iPros. In high-resolution mode, Vipers and ProJets can make parts with extremely tiny features and crisp details, while in normal-resolution mode, they can build cost-effective parts very quickly.

iPros have extremely large build volumes at 29 in. by 25 in. by 21 in. (736mm by 635mm by 533mm), yet are still able to image highly detailed parts easily.

Why Use SLA?

Stereolithography (SLA) is an additive manufacturing process that can 3D print parts with small features, tight tolerance requirements, and smooth surface finishes.

How Does SLA 3D Printing Work?

The SLA machine begins drawing the layers of the support structures, followed by the part itself, with an ultraviolet laser aimed onto the surface of a liquid thermoset resin. After a layer is imaged on the resin surface, the build platform shifts down and a recoating bar moves across the platform to apply the next layer of resin. The process is repeated layer by layer until the build is complete.

Newly built parts are taken out of machine and into a lab where solvents are used to remove any additional resins. When the parts are completely clean, the support structures are manually removed. From there, parts undergo a UV-curing cycle to fully solidify the outer surface of the part. The final step in the SLA process is the application of any custom or customer-specified finishing. Parts built in SLA should be used with minimal UV and humidity exposure so they don’t degrade.

SLA Resources

An Introduction to Stereolithography (SLA) 3D Printing

Stereolithography, a staple of 3D printing, can deliver complex prototypes quickly and accurately.

Read Design Tip

Selecting a Material for Stereolithography (SLA) 3D Printing

Compare materials for stereolithography with one another and with injection-molded plastics.

Read Design Tip

SLA vs. FDM: Comparing Common 3D Printing Technologies

See how these two 3D printing technologies stack up for prototype parts. Understanding the advantages of each will help accelerate design.

Read Blog

What is 3D Printing?

Gain an understanding of additive manufacturing and how it can be leveraged to improve product development through rapid prototyping and production.

Read Guide

Get an instant online quote for 3D printing.

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Guide to Stereolithography (SLA) 3D Printing

Stereolithography (SLA) 3D printing is the most common resin 3D printing process that has become vastly popular for its ability to produce high-accuracy, isotropic, and watertight prototypes and end-use parts in a range of advanced materials with fine features and smooth surface finish.  

In this comprehensive guide, learn how SLA 3D printers work, why thousands of professionals use this process today, and how SLA printers can benefit your work.

White Paper

Looking for a 3D printer to realize your 3D models in high resolution? Download our white paper to learn how SLA printing works and why it's the most popular 3D printing process for creating models with incredible details.

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Stereolithography belongs to a family of additive manufacturing technologies known as vat photopolymerization, commonly known as resin 3D printing. These machines are all built around the same principle, using a light source—a laser or projector—to cure liquid resin into hardened plastic. The main physical differentiation lies in the arrangement of the core components, such as the light source, the build platform, and the resin tank.

Watch how stereolithography (SLA) 3D printing works.

SLA 3D printers use light-reactive thermoset materials called “resin.” When SLA resins are exposed to certain wavelengths of light, short molecular chains join together, polymerizing monomers and oligomers into solidified rigid or flexible geometries.

A graphic representation of the basic mechanics of stereolithography (SLA) 3D printing.

SLA parts have the highest resolution and accuracy, the sharpest details, and the smoothest surface finishes of all 3D printing technologies, but the main benefit of the stereolithography lies in its versatility.

Material manufacturers have created innovative SLA resin formulations with a wide range of optical, mechanical, and thermal properties to match those of standard, engineering, and industrial thermoplastics.

Advancements in 3D printing continue to change the way businesses approach prototyping and production. As the technology becomes more accessible and affordable and hardware and materials advance to match market opportunities and demands, designers, engineers, and beyond are integrating 3D printing into workflows across development cycles. Across industries, 3D printing is helping professionals cut outsourcing costs, iterate faster, optimize production processes, and even unlock entirely new business models.

Stereolithography 3D printing in particular has undergone significant changes. Traditionally, SLA 3D printers have been monolithic and cost-prohibitive, requiring skilled technicians and costly service contracts. Today, small format desktop printers produce industrial-quality output, at substantially more affordable price points and with unmatched versatility.

Compare stereolithography 3D printing to two other common technologies for producing plastic parts: fused deposition modeling (FDM) and selective laser sintering (SLS).

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See how to go from design to 3D print with the Form 3+ SLA 3D printer.  This 5-minute video covers the basics of how to use the Form 3, from the software and materials to printing and post-processing.

 

 

Use any CAD software or 3D scan data to design your model, and export it in a 3D printable file format (STL or OBJ). Each SLA printer includes software to specify printing settings and slice the digital model into layers for printing. Once setup is complete, the print preparation software sends the instructions to the printer via a wireless or cable connection.

More advanced users may consider specifically designing for SLA, or taking steps like hollowing parts to conserve material.

After a quick confirmation of the correct setup, the printing process begins and the machine can run unattended until the print is complete. In printers with a cartridge system, the material is automatically refilled by the machine.

An online Dashboard from Formlabs allows you to remotely manage printers, materials, and teams.

 

Once the printing is completed, parts require rinsing in isopropyl alcohol (IPA) to remove any uncured resin from their surface. After rinsed parts dry, some materials require post-curing, a process which helps parts to reach their highest possible strength and stability. Finally, remove supports from the parts and sand the remaining support marks for a clean finish. SLA parts can be easily machined, primed, painted, and assembled for specific applications or finishes.

Post-curing is particularly important for functional resins for engineering, and mandatory for some dentistry and jewelry materials and applications.

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Engineers, designers, manufacturers, and more choose SLA 3D printing for its fine features, smooth surface finish, ultimate part precision and accuracy, and mechanical attributes like isotropy, watertightness, and material versatility.

Because 3D printing creates parts one layer at a time, completed prints may have variations in strength based on orientation of the part relative to the printing process, with different properties in X, Y, and Z axes.

Extrusion-based 3D printing processes like fused deposition modeling (FDM) are known for being anisotropic due to layer-to-layer differences created by the print process. This anisotropy limits the usefulness of FDM for certain applications, or requires more adjustments on the part geometry side to compensate for it.

Read our in-depth guide about FDM vs. SLA 3D printers to learn how they compare in terms of print quality, materials, applications, workflow, speed, costs, and more.

In contrast, SLA resin 3D printers create highly isotropic parts. Achieving part isotropy is based on a number of factors that can be tightly controlled by integrating material chemistry with the print process. During printing, resin components form covalent bonds, but layer to layer, the part remains in a semi-reacted “green state. ”

While in the green state, the resin retains polymerizable groups that can form bonds across layers, imparting isotropy and watertightness to the part upon final cure. On the molecular level, there is no difference between X, Y, or Z planes. This results in parts with predictable mechanical performance critical for applications like jigs and fixtures, end-use parts, and functional prototyping.

SLA printed parts are highly isotropic compared to those produced with fused deposition modeling (FDM).

Because they are isotropic, SLA printed parts like this jig from Pankl Racing Systems can withstand the variety of directional forces they undergo during high stress manufacturing operations.

SLA printed objects are continuous, whether producing geometries with solid features or internal channels. This watertightness is important for engineering and manufacturing applications where air or fluid flow must be controlled and predictable. Engineers and designers use the watertightness of SLA printers to solve air and fluid flow challenges for automotive uses, biomedical research, and to validate part designs for consumer products like kitchen appliances.

OXO relies on the watertightness of SLA printing to create robust functional prototypes for products with air or fluid flow, like this coffee maker.

Industries from dental to manufacturing depend on SLA 3D printing to repeatedly create accurate, precise components. For a print process to produce accurate and precise parts, multiple factors must be tightly controlled.

Compared to machined accuracy, SLA 3D printing is somewhere between standard machining and fine machining. SLA has the highest tolerance of commercially available 3D printing technologies. Learn more about understanding tolerance, accuracy, and precision in 3D printing.

The combination of the heated resin tank and the closed build environment provides almost identical conditions for each print. Better accuracy is also a function of lower printing temperature compared to thermoplastic-based technologies that melt the raw material. Because stereolithography uses light instead of heat, the printing process takes place at close to room temperature, and printed parts don't suffer from thermal expansion and contraction artifacts.

An example from the dental industry comparing a scanned component with the original CAD geometry, demonstrating the ability to maintain tight tolerances across an SLA printed part.

Low Force Stereolithography (LFS) 3D printing houses the optics inside a Light Processing Unit (LPU) that moves in the X direction. One galvanometer positions the laser beam in the Y direction, then directs it along across a fold mirror and parabolic mirror to deliver a beam that is always perpendicular to the build plane, so it is always moving in a straight line to provide even greater precision and accuracy, and allows for uniformity as hardware scales up to larger sizes, like Formlabs larger format SLA printer Form 3L. The LPU also uses a spatial filter to create a crisp, clean laser spot for greater precision.

The characteristics of individual materials are also important for ensuring a reliable, repeatable print process.

Formlabs Rigid Resin has a high green modulus, or modulus before post-curing, which means it’s possible to print very thin parts with precision and a lower chance of failure.

SLA printers are considered the gold standard for smooth surface finish, with appearances comparable to traditional manufacturing methods like machining, injection molding, and extrusion.

This surface quality is ideal for applications that require a flawless finish and also helps reduce post-processing time, since parts can easily be sanded, polished, and painted. For example, leading companies like Gillette use SLA 3D printing to create end-use consumer products, like 3D printed razor handles in their Razor Maker platform.

Leading companies like Gillette use SLA 3D printing to create end-use consumer products, like the 3D printed razor handles in their Razor Maker platform.

Z-axis layer height is commonly used to define the resolution of a 3D printer. This can be adjusted in between 25 and 300 microns on Formlabs SLA 3D printers, with a trade-off between speed and quality.

In comparison, FDM and SLS printers typically print Z-axis layers at 100 to 300 microns. However, a part printed at 100 microns on an FDM or SLS printer looks different from a part printed at 100 microns on an SLA printer. SLA prints have a smoother surface finish right out of the printer, because the outermost perimeter walls are straight, and the newly printed layer interacts with the previous layer, smoothing out the staircase effect. FDM prints tend to have clearly visible layers, whereas SLS has a grainy surface from the sintered powder.

The smallest possible detail is also much finer on SLA, given 85 micron laser spot size on the Form 3+, in comparison with 350 microns on industrial SLS printers, and 250–800 micron nozzles on FDM machines.

While FDM 3D printed parts tend to have visible layer lines and might show inaccuracies around complex features, parts printed on SLA machines have sharp edges, a smooth surface finish, and minimal visible layer lines.

SLA resins have the benefit of a wide range of formulation configurations: materials can be soft or hard, heavily filled with secondary materials like glass and ceramic, or imbued with mechanical properties like high heat deflection temperature or impact resistance. Material range from industry-specific, like dentures, to those that closely match final materials for prototyping, formulated to withstand extensive testing and perform under stress.

Rigid 10K Resin is a highly glass-filled material for industrial parts that need to withstand significant load without bending, including applications like injection molding.

In some cases, its this combination of versatility and functionality that leads to companies to initially bring resin 3D printing in-house. After finding one application solved by a specific functional material, it’s usually not long before more possibilities are uncovered, and the printer becomes a tool for leveraging the diverse capabilities of various materials.

For example, hundreds of engineers in the Design and Prototyping Group at the University of Sheffield Advanced Manufacturing Research Centre (AMRC) rely on open access to a fleet of 12 SLA 3D printers and a variety of engineering materials to support highly diverse research projects with industrial partners like Boeing, Rolls-Royce, BAE Systems, and Airbus. The team used High Temp Resin to 3D print washers, brackets, and a sensor mounting system that needed to withstand the elevated, and leveraged Durable Resin to create intricate custom springy components for a pick and place robot that automates composites manufacturing.

Engineers at the AMRC use a fleet of 12 SLA 3D printers and a variety of engineering materials to print custom parts for diverse research projects, like brackets for a pick and place robot (top), and mounts for sensors in a high-temperature environment (bottom).

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Need some help figuring out which 3D printing material you should choose? Our new interactive material wizard helps you make the right material decisions based on your application and the properties you care the most about from our growing library of resins.

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SLA 3D printing accelerates innovation and supports businesses across a wide range of industries, including engineering, manufacturing, dentistry, healthcare, education, entertainment, jewelry, audiology, and more.
 

Rapid prototyping with 3D printing empowers engineers and product designers to turn ideas into realistic proofs of concept, advance these concepts to high-fidelity prototypes that look and work like final products, and guide products through a series of validation stages toward mass production.

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Manufacturers automate production processes and streamline workflows by prototyping tooling and directly 3D printing custom tools, molds, and manufacturing aids at far lower costs and lead times than with traditional manufacturing. This reduces manufacturing costs and defects, increases quality, speeds up assembly, and maximizes labor effectiveness.

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Digital dentistry reduces the risks and uncertainties introduced by human factors, providing higher consistency, accuracy, and precision at every stage of the workflow to improve patient care. 3D printers can produce a range of high-quality custom products and appliances at low unit costs with superior fit and repeatable results.

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Affordable, professional-grade desktop 3D printing helps doctors deliver treatments and devices customized to better serve each unique individual, opening the door to high-impact medical applications while saving organizations significant time and costs from the lab to the operating room.

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3D printers are multifunctional tools for immersive learning and advanced research. They can encourage creativity and expose students to professional-level technology while supporting STEAM curricula across science, engineering, art, and design.

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High definition physical models are widely used in sculpting, character modeling, and prop making. 3D printed parts have starred in stop-motion films, video games, bespoke costumes, and even special effects for blockbuster movies.

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Jewelry professionals use CAD and 3D printing to rapidly prototype designs, fit clients, and produce large batches of ready-to-cast pieces. Digital tools allow for the creation of consistent, sharply detailed pieces without the tediousness and variability of wax carving.

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Hearing specialists and ear mold labs use digital workflows and 3D printing to manufacture higher quality custom ear products more consistently, and at higher volumes for applications like behind-the-ear hearing aids, hearing protection, and custom earplugs and earbuds.

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Many companies start using 3D printing via outsourcing to service bureaus or labs. Outsourcing production can be a great solution when teams require 3D printing only occasionally, or for one-offs that require unique material properties or applications. Service bureaus can also provide advice on various materials and offer value-added services such as design or advanced finishing.

The main downsides of outsourcing are cost and lead time. Often, outsourcing is a gateway to bringing production in-house as needs ramp up. One of the greatest benefits of 3D printing is its speed compared to traditional manufacturing methods, which quickly diminishes when an outsourced part takes multiple days or even weeks to arrive. With growing demand and production, outsourcing also rapidly becomes expensive.

Because of the rise of affordable industrial-quality 3D printing, today, more and more companies choose to bring 3D printing in-house right away, vertically integrating into existing shops or labs, or in the workspaces of engineers, designers, and others who could benefit from translating digital designs into physical parts or who are involved in small batch production.

Small format, desktop SLA 3D printers are great when you need parts quickly. Depending on the number of parts and printing volume, investment into a small format 3D printer can break even within months. Plus, with small format machines, it’s possible to pay for just as much capacity as a business needs and scale production by adding extra units as demand grows. Using multiple 3D printers also creates the flexibility to print parts in different materials simultaneously. Service bureaus can still supplement this flexible workflow for larger parts or unconventional materials.

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Fast turnaround time is a huge advantage to owning a desktop 3D printer. When working with a printing bureau, lead times, communication, and shipping all create delays. With a desktop 3D printer like the Form 3+, parts are in-hand within hours, allowing designers and engineers to print multiple parts in one day, helping to iterate faster and drastically reduce product development time and quickly test mechanisms and assemblies avoid costly tool changes.

Owning a desktop 3D printer results in significant savings over 3D printing service bureaus and traditional machining, as these alternatives rapidly becomes expensive with growing demand and production.

For example, to fulfill tight production deadlines, a process engineer and team at Pankl Racing Systems introduced SLA 3D printing to produce custom jigs and other low-volume parts directly for their manufacturing line. While in-house SLA was initially met with skepticism, it turned out to be an ideal substitute to machining a variety of tools. In one case, it reduced lead time for jigs by 90 percent—from two to three weeks to less than a day—and decreased costs by 80-90 percent.

CostLead Time
In-House SLA 3D Printing$9–$285–9 hours
CNC Machining$45–$3402–3 weeks
Outsourced 3D Printing $51–$1371–3 weeks

Pankl Racing Systems significantly reduced lead times and costs by 3D printing custom jigs in-house.

With small format machines, it’s possible to pay for just as much capacity as a business needs and scale production by adding extra units as demand grows. Using multiple 3D printers also creates the flexibility to print parts in different materials simultaneously.

The Design and Prototyping Group at the University of Sheffield Advanced Manufacturing Research Centre (AMRC) runs an open-access additive manufacturing station with a fleet of 12 Form 2 stereolithography (SLA) 3D printers for hundreds of engineers working on diverse projects across the site.

Formlabs offers two high precision SLA 3D printing systems, a growing library of specialized materials, intuitive print preparation and management software, and professional services—all in one package.

To continue exploring SLA 3D printing, start with feeling the quality of SLA for yourself: Request a free sample 3D printed part in your choice of material to be mailed straight to your door.

Request a Free Sample Part

SLA Technology. How SLA 3D printing works.

Hello everyone, 3DTool is with you!

Today we will look at the basic principles of technology SLA . After reading this article, you will understand the main points of the printing process using this technology, the advantages and disadvantages of this method 3D printing .

On our website, you can find a list of 3D printers working on SLA technology, at this link: Catalog of 3D printers printing on SLA / DLP technology

Technology 3 D printing SLA

Stereolithography (SLA) is an additive manufacturing process that achieves the result by means of resin polymerization. In SLA printing, the object is created by selectively curing a polymer resin, layer by layer, using an ultraviolet (UV) laser beam. The materials used in SLA printing are photosensitive thermoset polymers that are available in liquid form.

SLA is known as the first 3D printing technology : its inventor patented this technology back in 1986 . When you need to print parts with very high precision or a smooth surface, the SLA comes to the rescue. In this case, it is the most cost-effective and efficient technology 3D printing . The best results can be achieved only if the operator of the equipment on which the printing process takes place is familiar with the technology and some of the nuances. That is, he has the necessary qualifications.

SLA shares many characteristics with Direct Light Processing (DLP ), another photopolymerization technology. For simplicity, both technologies can be considered equal.

SLA printing process

1) 2) 3)

1) A platform is placed in the tank with liquid photopolymer, at the same height from the resin surface.

2) The UV laser then selectively cures the required areas of the photopolymer resin according to a predetermined algorithm.

The laser beam is focused on a given path using a set of mirrors called galvos. Then the entire cross-sectional area of ​​the model is illuminated. Therefore, the resulting part is completely solid.

3) When one layer is finished, the platform moves to a safe distance and the mixing foot inside the tub mixes the resin.

This process is repeated until the part is printed. After printing, the part is not fully cured and requires further post-processing under the UV lamp . At the end of UV illumination, the part acquires very high mechanical and thermal properties.

The liquid resin solidifies through a process called photopolymerization: during solidification, the monomer carbon chains that make up the liquid resin are activated by an ultraviolet laser and become solid, creating strong, inextricable bonds with each other.

The photopolymerization process is irreversible, and there is no way to convert the resulting parts back into a liquid state. When heated, they will burn, not melt. This is because the materials that are produced by SLA technology are made from thermoset polymers, as opposed to the thermoplastics that FDM uses.

Operation scheme SLA printer

Specifications SLA printer

On SLA systems, most print settings are set by the manufacturer and cannot be changed. The only inputs are the layer height and the part orientation ( last, locates the supports ).

The typical layer height in a SLA print ranges from 25 to 100 micron .

The lower the layer height, the more accurately the complex geometry of the model will be printed, but at the same time the printing time and the likelihood of failure will increase. A layer height of 100 microns is suitable for most common geometries and is the golden mean.

Another important parameter for the operator is the size of the platform. It depends on the type of SLA printer. There are two main types: orientation top to bottom and orientation from bottom to top .

In the first case, the laser is above the tank, and the part is face up. The platform sits at the very top of the resin vat and moves down after each layer is sintered.

Schematic SLA top-down printer

In " bottom up " layout on SLA printers , the light source is placed under the resin tank (see picture above) , and the part is built upside down.

The tank has a transparent bottom with a silicone coating that allows the beam of light to pass through but prevents the cured resin from sticking. After each layer, the cured resin separates from the bottom of the tank as the platform moves up. This is called the sintering step.

Schematic SLA bottom-up printer

The orientation " bottom to top " is mostly used in desktop printers like Formlabs. The " top - down " orientation is used in the industrial SLA printer .

Printers SLA " bottom-up " are easier to manufacture and operate, but the size of the possible print will be smaller, since the forces applied to the part during the sintering stage can cause printing to fail.

Top-down printers, on the other hand, can print very large parts without much loss in accuracy. The wide possibilities of such systems naturally cost more.

The following are the main characteristics and differences between the two orientations:

"Top down "

Pros:

lower cost

Wide market availability

Minuses:

Small platform size

Smaller range of materials

Requires additional post-processing due to extensive

use of supports

Popular brands:

FORMLABS

Printable area: Up to 145 x 145 x 175 mm

Typical layer height and print accuracy: 25 to 100 µm and ± 0. 5% (lower limit: ± 0.010 to 0.250 mm) respectively

"Down up"

Pros:


Very large platform

Faster Print Time

Minuses:

High price

Qualified operator required

Material change involves emptying the entire tank

Popular brands:

PRISMLAB

Print area size: Up to 1500 x 750 x 500 mm

Typical layer height and print accuracy: 25 to 150 µm and ± 0.15% (lower limit ± 0.010 to 0.030 mm) respectively

Support during printing 3 D

Supports are always required at Print SLA . Structural structures are printed from the same material as the part and must be manually removed after printing.

Part orientation determines the location and amount of supports. It is recommended that the part be oriented so that surfaces that require maximum quality do not come into contact with supports.

In different types of SLA printers, support is used in different ways:

For top - down printers , support requirements are the same as FDM . They are essential for accurate printing of overhangs and bridges ( the critical overhang angle is typically 30 degrees ).

The part can be oriented in any position and is usually printed flat to minimize the number of supports and the total number of layers.

In printers like " from bottom to top " everything is more complicated. Overhangs and bridges also need to be supported, but minimizing the cross-sectional area of ​​each layer is the most important criterion.

Forces applied to the part during the sintering step can cause it to come off the platform. These forces are proportional to the cross-sectional area of ​​each layer.

For this reason, the parts must be oriented at an angle, and minimizing supports here is not a primary concern.

On the left - a detail oriented on the SLA printer "from top to bottom" (support minimization).

On the right is a part oriented on the SLA printer "from the bottom up" (minimizing the cross-sectional area).

Removing supports for an SLA printed part

Curl

One of the biggest problems with the accuracy of parts made with SLA is curling. This problem is similar to the deformation in FDM when materials shrink.

During curing, the resin shrinks slightly when exposed to the printer's light source. When shrinkage is significant, large internal stresses develop between the new layer and the previously cured material, causing the part to twist.

Adhesion (sintering) between layers

SLA printed parts have isotropic mechanical properties. This is due to the fact that one pass UV beam is not enough to completely cure the liquid resin.

Further passes help the previously hardened layers to fuse together. In fact, in the SLA of printing, curing continues even after the printing process is completed.

To achieve the best mechanical properties, parts printed using this technology should be post-cured by placing them in a chamber under intense ultraviolet radiation ( and sometimes at elevated temperatures ).

This greatly increases the hardness and heat resistance of SLA , but does not make it stronger. Rather the opposite.

For example.

Test specimens printed with standard clear resin on a SLA desktop printer have almost 2 times tensile strength after curing ( 65 MPa compared to 38 MPa).

Can operate under load at higher temperatures ( 58 degrees Celsius, compared with 42 degrees ), but their elongation at break is half as much ( 6.2% compared to 12% ).

If you leave the part in the sun, then nothing good will come of it.

Prolonged exposure to ultraviolet radiation has a detrimental effect on physical properties and appearance. The part may curl, become very brittle, and change color.

For this reason, before using the part, it is recommended to apply a spray of transparent acrylic paint resistant to UV .

SLA media

SLA Printing Materials is available in the form of a liquid resin. The price per liter of resin varies greatly - ranges from $50 for standard material to $400 for specialty materials such as casting or dental resin.

Industrial systems offer a wider range of materials than desktop systems SLA printers, which give the designer more control over the mechanical properties of the printed part.

SLA materials ( thermosets ) are more brittle than materials made using FDM or SLS ( thermoplastics ) and for this reason SLA parts are not typically used for functional prototypes that will be subjected to significant stress. However, new advances in materials development may change this in the near future.

The following table lists the advantages and disadvantages of the most commonly used resins:

Material

Features

Standard resin

+ Smooth surface

Relatively fragile part

transparent resin

+ Transparent material

- Requires post-processing for Presentable appearance

casting resin

+ Used to create mold templates

+ Low ash after burnout

Rigid or durable resin

+ ABS-like or PP-like mechanical properties

- Low thermal resistance

High temperature resin

+ High temperature resistance

+ Used for injection molding

· - High price

dental resin

+ Biocompatible

+ High abrasion resistance

· - High price

Rubber-like resin

+ Rubber-like material

- Poor printing accuracy

Post-processing SLA 3D printing

Parts printed with SLA technology can be processed to a high quality using various methods such as sanding and polishing, staining and mineral oil treatment. Widely developed articles about post-processing can be found on the Internet.

Transparent resin housing cover for electronics in various finishes. From left to right: removal of the main support, wet sanding, UV irradiation, acrylic and polishing

Advantages and disadvantages of SLA

Pros:

  • SLA 3D printers can produce parts with very high dimensional accuracy and complex geometries.

  • The parts will have a very smooth surface, making them ideal for visual prototypes, for example.

  • Special materials are available such as clear, flexible and cast resins.

Cons:

  • Parts printed using SLA technology tend to be fragile and not suitable for functional prototypes.

  • The mechanical properties and appearance of these parts deteriorate over time. They are adversely affected by exposure to sunlight.

  • Supports and post-processing when printing are always required.

The main characteristics of the SLA are shown in the table:

materials

Photopolymer resins (thermosetting

materials)

Dimensional accuracy

± 0.5% (lower limit: ± 0.10 mm) - domestic
± 0.15% (lower limit ± 0.01 mm) - industrial

typical size

print area

Up to 145 x 145 x 175 mm - for desktop printers
Up to 1500 x 750 x 500 mm - for industrial

Total layer thickness

25 - 100 µm

Support

Always required

(Needed to make an accurate part)


Total

  • SLA print is best for producing visual prototypes with very smooth surfaces and very fine detail.

  • Desktop SLA 3 D The printer is ideal for making small, about the size of an adult's fist, injection molded parts. Moreover, such a printer can be purchased at an affordable price.

  • Industrial SLA 3 D printers can produce very large parts (up to 1500 x 750 x 500 mm)

Well, that's all we have! Thank you for being with us, see you soon. Further it will be more interesting!

You can purchase the 3D printers mentioned in the article , consumables for them, ask your question, or track the order, you can

  • By phone: 8(800)775-86-69

  • E-mail: [email protected]

  • Or on our website: https://3dtool.ru/

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SLA 3D printing technology

Laser stereolithography (SLA) is a 3D printing technology based on the layer-by-layer curing of a liquid material under the action of a laser beam.

Alternative: SLS (higher product strength), PolyJet and MJP (lower finished product cost).

What is better to print: functional prototypes, high-precision products, burnt-out master models.

Advantages: high construction speed, complex geometry, excellent detail and surface quality.

Alternative: SLS (higher product strength), PolyJet and MJP (lower finished product cost).

Professional SLA printers feature large build chambers

Professional SLA printers feature large build chambers

How it works

A mesh platform is placed in a container with liquid photopolymer, on which the prototype will be grown. Initially, the platform is installed at such a depth that it is covered by the thinnest layer of matter, only 0.05-0.13 mm thick - in fact, this is the layer thickness in laser stereolithography. Next, a laser is turned on, affecting those parts of the polymer that correspond to the walls of a given object, causing them to harden. After that, the entire platform is immersed exactly one layer, that is, to a depth of 0.05-0.13 mm.

How it works

A mesh platform is placed in a container with liquid photopolymer, on which the prototype will be grown. Initially, the platform is installed at such a depth that it is covered by the thinnest layer of matter, only 0.05-0.13 mm thick - in fact, this is the layer thickness in laser stereolithography. Next, a laser is turned on, affecting those parts of the polymer that correspond to the walls of a given object, causing them to harden. After that, the entire platform is immersed exactly one layer, that is, to a depth of 0.05-0.13 mm.

After printing is completed, the object is immersed in a bath with a special composition to remove excess elements and completely clean. Then - the final irradiation with light for the final hardening. Like other 3D prototyping techniques, SLA requires the printing of supporting structures, which are then removed.

After printing is completed, the object is immersed in a bath with a special composition to remove excess elements and completely clean. Then - the final irradiation with light for the final hardening. Like other 3D prototyping techniques, SLA requires the printing of supporting structures, which are then removed.

Technology features

  • Production of models of any complexity (thin-walled parts, small parts)
  • Light processing of the manufactured prototype
  • High build accuracy and high surface quality
  • The properties of the polymers used make it possible to use the grown prototype as a finished product
  • Larger chamber than other 3D printers
  • Low support consumable percentage
  • Low Noise

Most SLA 3D printers produce objects around 50x50x60 cm, but there are exceptions. The American company 3D Systems has created a device capable of creating objects much larger than classical ones - 1500x750x550 mm, which opens up new horizons for the application of this technology.

Technology features

  • Production of models of any complexity (thin-walled parts, small parts)
  • Light processing of the manufactured prototype
  • High build accuracy and high surface quality
  • The properties of the polymers used make it possible to use the grown prototype as a finished product
  • Larger chamber than other 3D printers
  • Low Support Consumable
  • Low Noise

Most SLA 3D printers produce objects around 50x50x60 cm, but there are exceptions. The American company 3D Systems has created a device capable of creating objects much larger than classical ones - 1500x750x550 mm, which opens up new horizons for the application of this technology.

Applications

Scientific research

Since it is possible to obtain a plastic model of almost any complexity for any purpose in a matter of hours, SLA technology becomes an indispensable assistant in various kinds of scientific research. Models have sufficient strength and transparency, so it is possible to visualize gas and hydrodynamic flows inside the models.

Medicine

In maxillofacial surgery and orthodontics, a new direction has been formed with the advent of SLA. The patient is given magnetic resonance imaging of the problem area, a 3D computer model is formed from it, and a real 3D model of bone tissue is grown from it. Thus, the doctor already the next day has at his disposal a model of the bones or teeth of a real patient.

Burnt-out casting

If there is a need to obtain a metal part, the following technology is used: the SLA model is poured with molding sand, then calcined at high temperatures (up to 1000 °C). In this case, the plastic completely burns out, and metal is poured into the formed mold under vacuum in its place. After it solidifies, the form is destroyed and the part is removed.

Art

Sculptors, fashion designers and jewelers are taking production to the next level with laser stereolithography technology. The process of 3D printing of prototypes significantly reduces the time for testing experimental samples, which has a positive effect on the speed and quality of creating a future piece of jewelry or sculpture. SLA technology is very well suited for this: the models are durable and easy to paint.

Applications

Scientific research

Since it is possible to obtain a plastic model of almost any complexity for any purpose in a matter of hours, SLA technology becomes an indispensable assistant in various kinds of scientific research. Models have sufficient strength and transparency, so it is possible to visualize gas and hydrodynamic flows inside the models.

Medicine

In maxillofacial surgery and orthodontics, a new direction has been formed with the advent of SLA. The patient is given magnetic resonance imaging of the problem area, a 3D computer model is formed from it, and a real 3D model of bone tissue is grown from it.

Learn more