Stereolithography Printing Guide

Guide to SLA 3D Printing

Scott Gabdullin
Scott Gabdullin

Updated on November 15, 2023

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The ability to print three-dimensional objects is an astounding technological advancement that has transformed how many industries conduct business. There are many types of 3D printers made for accomplishing different things. So what are the best or most effective 3D printers, and how do they work? 

Stereolithography (SLA) 3D printing is a popular and cost-effective printing technology. SLA is very accessible, as individuals in various professions can use it to their advantage. In our guide to Stereolithography (SLA) 3D printing, we will tell you everything you need to know to understand and appreciate the SLA printer.

Table of Contents

What Is Stereolithography (SLA) 3D Printing?

Stereolithography (SLA) is a type of 3D printing used to bring complex concepts, prototypes, and parts into physical form. SLA technology slowly creates a 3D object, layer by layer, using a specific liquid material. 

Additive manufacturing, otherwise known as 3D printing, is typically considered the best method for crafting a prototype.

SLA 3D printing is a valuable tool utilized by many industries to test and conceptualize new products and models. However, SLA is not just 3D printing. Instead, SLA is a category within the trade or hobby. 

SLA is specifically different from other types of 3D printing that use thermoplastics or nylon-based materials because SLA uses thermoset liquid. Different industries will have different needs when deciding whether to use an SLA printer or another type of printer. The distinction between the liquids and what they can reproduce when printed is just one factor we will consider in depth below. 

What Is Vat Polymerization?

Stereolithography (SLA) 3D printing uses vat polymerization. Industry professionals also refer to vat polymerization as an additive manufacturing process. This process essentially means that the printer uses light to harden a material. 

Vat polymerization hardens material layer by layer to create something delicate, smooth, and detailed. The first step of the vat polymerization uses a vat, or tank, filled with photopolymer or resin. The tank holds the resin and begins building a model on the build platform. 

Layer by layer, an object is formed and hardened as the machine moves to the next layer. Once the machine completes the final layer, the printer stops, and you can remove the object from the build platform. When using an SLA 3D printer, you can build almost anything.

Five Other Types Of 3D Printers

Aside from stereolithography (SLA) 3D printing, there are five other 3D printers that industries commonly use for plastic printing. We will cover each in depth below.

The five other types of 3D printers are Selective Laser Sintering (SLS), Fused Deposition Modeling (FDM), Material Jetting Drop on Demand (DOD), Binder Jetting, and Powder Bed Fusion (DMLS, SLM, EBM).

Selective Laser Sintering (SLS)

Selective Laser Sintering (SLS) is a printing machine that uses a CO2 laser to fuse nylon powder material layer by layer. A roller on the printer rolls over the build platform to distribute the next layer of nylon powder. 

The model an SLS printer makes is rougher than SLA. SLS is great for making functional prototypes and parts. 

Fused Deposition Modeling (FDM)

Fused Deposition Modeling (FDM) is an additive manufacturing printer that uses thermoplastic polymers that are melted and assembled layer by layer. The material falls from an extrusion head and nozzle

FDM printers layer by adhering to the previous layer, which requires re-melting the material for it to stick. The adhesive process causes models to warp and take on a more oval-like shape than intended. 

Material Jetting Drop on Demand (DOD)

Material Jetting Drop on Demand (DOD) is a 3D printing process that essentially drops material on a build plate and cures it. The printer works similarly to an ink printer, but it layers the ink to create a 3D model instead of a two-dimensional image. 

DOD printers are great for creating patterns and moulds. 

Binder Jetting

Binder Jetting uses a powdered material and a liquid binder to create a 3D object. The printer works similarly to an SLS printer but uses the binder as the layering adhesive. Binder jetting can print in color and uses materials like metal, polymers, and ceramic.

Binder jetting is faster than other printers, and the binder powder combination allows for multiple fusions of materials. 

Powder Bed Fusion (DMLS, SLM, EBM)

Powder Bed Fusion includes the Direct Metal Laser Sintering (DMLS), Selective Laser Melting (SLM), and Electron Beam Melting (EBM) printers. Powder Bed Fusion uses a heat source to bind powder material together to create a 3D object. 

DMLS and SLM are exclusively metal material printers. DMLS heats metal powder to make it porous, while SLM melts the powder into one unit. Both DMLS and SLM can print strong prototypes and models like jewelry, dental products, and spare parts. 

EBM printers use a high-powered electron beam, allowing less energy to be used and layers to be produced fast. These printers are great in hardy industries like aerospace, motorsports, and metal prosthetics. 

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History Of Stereolithography (SLA) 3D Printing

According to the American Society of Mechanical Engineers (ASME), the majority recognizes Chuck Hull as the inventor of stereolithography. In 1984, Hull filed for a patent for SLA, and received it in 1986.

While Hull is certainly on record as the inventor of SLA, Dr. Hideo Kodama of the Nagoya Municipal Industrial Research Institute in Japan was the first to demonstrate the creation of 3D objects using plastic materials and UV exposure.

Moreover, while Dr. Kodama demonstrated his success in 1980, Hull was the first to patent and commercialized SLA 3D printing systems. Other notable additions that led 3D printing to advance to where it is today are Joseph E. Blather, the first to propose layering to create 3D topographical maps, and Matsubara, the first to propose stacking and photo-hardening polymers. 

Anatomy Of Stereolithography (SLA) 3D Printing

SLA printers have four important mechanics that allow them to create 3D prints. The four sections are: tank, build platform, laser, and control unit. The function of each of these four mechanics are:

The tank holds the liquid resin. This component is usually clear. 

Build Platform
The build platform is the surface that the SLA printer prints on. 

The SLA printer has an ultraviolet laser that cures the model. 

Control Unit
The control unit is the computer that communicates with the printer to create the model. It controls the build platform and the laser.

Stereolithography (SLA) 3D Printing Materials

When SLA printing, there are various types of materials that you can use to print a model. For example, there are standard resins, engineering resins, dental resins, and more. Let’s discuss the various types of resin materials to determine what is best for you and your particular project.

Standard Resin
Standard resin with SLA printer prints high-quality, smooth models. This type of resin doesn’t require post-curing and it is mainly used to craft prototypes, products, and other models. 

Tough Resin
Tough resin with an SLA printer has various hardness levels to fit the desired outcome. For example, engineering resin can be tough, durable, flexible, or temperature resistant. To illustrate the use of engineering resin, this type of resin can be used to create consumer products, like a helmet or spray bottle. 

Dental Resin
Dental resin is specific to the dental industry. This resin is used to make 3D models of a patient’s mouth or as an outline for dental surgery. 

Jewelry Resin
Jewelry resin is a great way for a jewelry designer to craft a model of their intended design. For example, when designing a ring that requires gems to fit snugly into the ring’s face, creating a 3D model is a valuable resource for a jewelry designer. 

Or for example, if a jeweller needs to fit a ring for a client, a 3D model can be built so the final product fits perfectly. 

Stereolithography (SLA) 3D Printing Systems

SLA systems use a special light source to cure the liquid material into firm plastic. According to FromLabs, there are two types of SLA systems: desktop and industrial. 

Desktop SLA: Inverted Versus Industrial SLA: Right-Side Up

Industrial is a right-side SLA, meaning the printing machine wraps the liquid material holder in the middle. For the most part, the right-side SLA is used by larger industrial systems, requiring a large volume of high-quality 3D prints. 

While the right-side SLA can handle an industrial-size volume of prints, it’s truly an investment for any company as its initial purchasing price and maintenance following are expensive. Maintenance of an industrial right-side machine is extremely crucial, as an unsteady machine leads to printer malfunction and failure. 

Desktop SLA is an upside-down, inverted SLA, meaning the resin material holder is at the base with the builder platform at the top. The laser focuses upwards from the bottom to cure the resin as it layers on the base. 

The appeal of the desktop SLA is that it can handle a higher build volume than the contents in the tank. This is because the resin material holder only requires at least a layer of liquid resin to cover the bottom. In turn, the desktop SLA is easier to maintain than the industrial SLA. Moreover, the starting price for the desktop SLA is less expensive than the industrial SLA. 

Stereolithography (SLA) 3D Printing Workflow

The workflow process to print a 3D object with a stereolithography (SLA) printer has six steps. Make sure to follow each below to ensure that your project, whether industrial or hobby-based, comes to fruition. 

Step 1: Design
Using computer-aided design (CAD) software, the SLA developer creates their three-dimensional model on the computer. To create the perfect model on an SLA printer, the model must be mathematically precise. Once the object is created, the developer will export it into a .STL or .OBJ file, so the SLA printer can understand the file.

Step 2: Prepare 
The preparation step of SLA 3d printing requires the creator to tweak the printing settings and separate their model into various layers so it can print correctly. Some of the setting options on the printer include height, material, and support structure.

Many times the model can be sent wirelessly to the printer; however, some require a wired connection.

Step 3: Print 
The printing process begins as soon as the developer sends the model to the machine. Depending on the model, the printing process can take hours, so the developer often leaves the printer running unattended until the print job is complete. Sometimes, maintenance throughout the printing process is required. For example, some printers may require the developer to refill the printing material. 

Step 4: Cure
During the printing stage, as the resin layers onto the build platform, the printer’s UV light cures the model following the printing process.

Step 5: Clean 
Once the printer finishes printing the model, the next step is to remove the build platform from the printer and deep clean the machine. You must rinse the resin holder with isopropyl alcohol to remove any remaining resin from the holder. 

Step 6: Finish
After removing the model from the build platform, the developer will remove the support beams, sand, prime, paint, and assemble the model. 

The Pros And Cons Of Stereolithography (SLA) 3D Printing

SLA 3D printing has various advantages and disadvantages over other forms of 3D printers available. Some pros of SLA 3D printing are as follows: 

  • Ability to print models of the highest quality
  • Create prototypes, parts, models, etc. quickly
  • Craft complex and accurate models
  • Work seamlessly with a machine
  • Never waste liquid resin

While there are many pros to SLA printing, there are some cons. We have listed a few common complaints about SLA 3D printers below: 

  • Expensive
  • Tedious post-printing process, i.e., sanding, polishing, painting
  • Not environmentally friendly
  • The developer must be taught how to use the machine properly

Unfortunately, liquid resin is not environmentally friendly. Most of the resin types contain toxic chemicals, making them extremely harmful to the environment. At the same time, however, there are a few biodegradable, non-toxic resins that SLA printers accept. 

Why Stereolithography (SLA) 3D Printing Is Great

While there are some drawbacks, SLA 3D printing remains a valuable technology that can help advance old design, prototyping, and modeling processes. 

High-Quality Models
Unlike Fused Deposition Modeling (FDM) and Selective Laser Sintering (SLS) printers that print at 100 and 300 microns, SLA uses a Z-axis layer height that you can adjust between 25 and 100 microns.

Unlike FDM models with visible layers and SLS models that can appear grainy and bumpy, SLA models appear smoother due to the quality of the materials used in the printing process. 

SLA 3D printers are more accurate than other 3D printers, making them a crucial printer for assembling jewelry, dental products, and more. Moreover, the SLA 3D printer obtains accuracy because of the smaller area needed to print its materials and its lower printing temperature. 

In addition, a UV laser cures the printer liquid resin instead of other machines that warm the internal temperature to harden the material, which causes expansion. 

Creative Freedom
SLA printers can print at 300 microns or less, allowing models to have small details that would otherwise be difficult to make in alternative printers. Moreover, the software used to create a model for printing makes it easy to manufacture these models using the same outline. 

SLA prints models fast. The fast printing process makes this a crucial machine for engineers who need to test a product fast and tweak the model to fit their tools. Moreover, since the model is designed using CAD software, multiple users can work on one project to make the creation process even faster. 

Cost vs. Value
Although SLA printers are often expensive, overall productivity accounts for the cost. The ability to rapidly print prototypes over and over again makes the creation process quicker and more accurate than making prototypes by hand or one by one. 

In addition, the cost of maintenance and materials is cheaper and faster than outsourcing or crafting by hand. 

Industries That Benefit From Stereolithography (SLA) 3D Printing

Many industries benefit from stereolithography (SLA) 3D printing. Specifically, the industries that benefit most from 3D printing are healthcare, education, construction, robotics, and inventors. Below we will look at the benefits in depth. 

3D printing has critically advanced the healthcare industry. With 3D printing, the industry creates skin, body parts, dental, and organs. Physicians can use 3D printing to create necessities for patients like skin, body parts, and organs with cells. Moreover, dentists can use SLA printers to create a 3D model of a patient’s teeth mold. 

On top of that, the healthcare industry uses 3D printing to create surgical tools and print models of patient injuries. 

Sectors of the education industry, like engineering, architecture, and chemistry, can use 3D printing to their advantage. Engineering students can easily print a prototype, architecture students can quickly print their designs, and chemistry students can create 3D models of molecules. 

The possibilities of 3D printing for STEM students is limitless. It allows students to enhance the learning experience and provides educators with physical models to help students understand these complex subjects.

The construction industry has quickly found a way to utilize 3D printers to their advantage. 3D printings can help build intricate designs, craft furniture, and more at a cheaper and faster rate. 

For example, 3D printers can craft furniture. Specifically, interior designers can create specially customized pieces for their clients.

3D printers can quickly and accurately craft complex parts needed in the robotics industry. For example, specific robot parts that usually require labor and planning can be printed with a 3D printer. This process has helped revolutionize this budding industry. 

Since 3D printing offers a realm of limitless possibilities, people are always creating something new using CAD software. For example, people have created one-of-a-kind 3D models to increase their productivity, like an SD card holder or laptop platform. 

The freedom to design and bring your design to life using a 3D printer opens up limitless possibilities for inventors. 

10 Tips And Tricks For Pristine Stereolithography (SLA) 3D Prints

Now that we know the fundamentals of SLA printing, here are ten tips and tricks to help you perfect your stereolithography (SLA) 3d prints:

Run Tolerance Tests
Running tolerance tests provides vital information on certain features of your model. For example, tolerance tests can tell you how thin of a print your printer can handle. 

Consider Splitting Your Model 
Whenever possible it’s beneficial to cut your model in half or more for printing. Each section of your model can easily attach, and it excels in the printing process. 

Try to Keep the Number of Supports Low
While supports are required for 3D printing, limiting the number of supports your model needs will lower production and material costs and the post-printing process. 

Keep Model Close to the Build Platform
On top of keeping the number of supports low, keeping your model as close to the surface as possible will accelerate the printing process. Keeping your model close to the build platform simply means fewer layers are required to run for the printer to reach the point of actually printing your model. 

Make Holes Wherever Possible
Holes are a great way to keep material costs low and speed up the production process. That being said, wherever there are areas you can hollow out your design or add an empty slot without disrupting the design, do it.

Follow the Manufacture Suggestions for Resin Storage
The liquid resin should be kept at room temperature. Your resin packaging likely recommends storing the resin in a cooler, room temperature environment to avoid damage. 

Always Clean the Machine
After a print, it’s important to clean the platform and material cartridge with isopropyl alcohol. Keeping up with machine maintenance will save you in the long run.

Be Consistent When Using a UV Light for Curing
Curing following the print stage is mandatory, and it’s important to have a consistent light curing all sides of your model.

Fill the Resin Tank All the Way
Filling the resin tank to maximum capacity will help the machine run through the resin and avoid having to refill in the middle. It will also speed up the printing process since the printer won’t stall once it runs out of material. 

Always Wear Protection
When dealing with resin, it’s important to wear gloves. Most resin contains toxic chemicals, so it should be handled with care. On that note, there should be no excuse when properly disposing of resin, i.e., not dumping it in the environment. 

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Final Thoughts

Hopefully with our guide on stereolithography (SLA) 3D printing you’ve learned the what, the history, the anatomy, the material, the different types of systems, the workflow process, the industries involved, the pros and cons of SLA printers, and more. 

As a popular 3D printing technology, there are various industries (as discussed above) that utilize stereolithography (SLA) 3D printing to their advantage. The design possibilities are nearly limitless with SLA, and, on top of that, it’s a more cost-effective method for 3D printing.

SLA Printing FAQ

Hopefully, we’ve answered all your questions about SLA prints. But, if we missed some, hopefully, we’ll answer it below. Here are some frequently asked questions about stereolithography (SLA) 3D printing.

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