Stereolithography advantages and disadvantages

Posted On 10 August 2022 By Anastasios Pantelis

What are the advantages and disadvantages of Stereolithography?

While stereolithography (SLA) is the oldest commercial 3D printing technology and there are now many more available, it could still be the best answer for your next project.  Whether you choose to use it or one of the other six technologies that we have depends on what you need to achieve.  Here we take a brief look at the technology and assess its advantages and disadvantages.

A good place to start is looking at the process which will give you some pointers as to whether it could be right for your project or not.

The Stereolithography process

The process works by focusing an ultraviolet laser into a vat of photopolymer resin to cure it.  Using your CAD, this laser draws a preprogrammed design or shape. Generally, we create the support structures first followed by the part itself. 

After curing each build layer on the resin surface, this build platform shifts down and a recoating bar moves across to apply the next layer of resin which is in turn cured by the UV laser. This is then repeated layer by layer until the build is finished.

We then take newly built parts out of the machine and use solvents to remove any additional resins.

The advantages of Stereolithography

Speed: One of the major advantages of the process is that, depending on the part you need, it is quick since curing is fast.  Exactly how long it will take will depend on the size, complexity and layer thickness of the part.  After uploading your CAD, we can ship your parts in as little time as a day.

This also makes it great for generating tooling fixtures, which can sometimes be an afterthought and take manufacturing engineers by surprise.  SLA can help overcome such oversights by creating fixtures and fittings quickly.

Cost effective: It can also be a very cost-effective process to develop low cost but accurate models.  This makes it ideal for cosmetic prototypes to help you detect design flaws before you move onto more costly prototyping or final manufacturing.  For the right projects – notably the medical industry, it is also a great option for low volume production of parts and can provide quick lead times for this.

Accuracy: SLA is renowned for producing extremely smooth parts that can even rival injection moulding.  They achieve extremely good tolerances for features of up to +/- 0.05mm in the X and Y axes and 0.13mm in the Z axis.  And with new materials such as our own MicroFineTM Green and Grey you can achieve micro resolution parts perhaps for medical or consumer electronics.

Scaling is simple

While the time taken to produce a part can depend on its size and there are maximum size limitations, it is easy to scale a part since the process is driven by CAD.

Snap together assemblies

Because we can take models straight from CAD it is possible to create assemblies based on many component parts that you can fit together to form a larger part.  This makes it easy to check an assembly and quickly change and reprint a design if it needs modification – so it is great for form and fit testing.

Limitations of Stereolithography

If stereolithography is not the right answer for your next project then it’s worth noting that there are now many different additive manufacturing technologies available to you.  At Protolabs, for example, we currently offer six different additive manufacturing processes, some of which maybe better suited to your individual project.

So, let’s take a look at some of SLA’s limitations.

Material choice

Because of the nature of curing there are only a limited number of materials available using stereolithography.  And as you may have realised, because it uses a UV laser to cure the resin, the parts are photosensitive so would not be suitable for outdoor applications.

This could also affect other characteristics of your prototypes or parts.  Other 3D printing processes such as selective laser sintering can use a wider range of engineering grade materials that will generally be more durable to produce higher strength parts. And it’s the same story for other characteristics so if you need better heat and chemical resistance then another material using a different technology might give a better solution.

When to use Stereolithography

As with any rapid prototyping or final production process whether stereolithography is the right choice for your next project will depend on what you want to achieve and where you are in the product development process

We find that it is a great choice for cosmetic prototypes, for form and fit testing and if you need high accuracy and an excellent surface finish.  But remember unlike the 1980s it is not the only choice available to you. 

At Protolabs, for example, we have invested in 6 different technologies that can produce prototypes and production ready parts from a wide range of plastics and metals. For some projects you may also find that CNC machining or on demand injection moulding provides a better answer.

Whatever your needs you don’t need to make the decision on your own.  Our application engineers are well versed in all the technologies that we use.