What Is Stereolithography, Who Invented It, and When?

Stereolithography (SLA) is a popular photopolymer resin-based 3D printing technology known for its transformative influence in manufacturing and beyond. The impressive level of detail, surface quality and high accuracy offered by SLA makes it ideal for producing aesthetic models, functional prototypes, and complex parts. It is used in a wide variety of industries, from aerospace to healthcare.

In this guide, we’ll explore what stereolithography 3D printing is, how it works, and its fascinating history. We’ll also discuss what SLA is used for today, and explore some of its applications in various industries.

What Is Stereolithography?

Stereolithography, often abbreviated as SLA, is a 3D printing method that uses a powerful laser to selectively cure liquid resin into a three-dimensional object. The term originates from the Greek words “stereo” meaning solid, “litho” meaning stone, and “graphy” meaning writing.

Like other additive manufacturing technologies, SLA 3D printing builds objects layer-by-layer, rather than cutting them from larger pieces of material. This allows for the creation of extremely detailed, complex, and unique parts. The process is entirely computer-controlled, which significantly reduces the potential for human error, resulting in unparalleled precision and consistency.

How Does Stereolithography Work?

At the heart of stereolithography is the science of photopolymerisation. This is a process whereby a liquid is transformed into a solid structure, or cured, through exposure to ultraviolet (UV) light. In the case of SLA 3D printing, a moving UV laser is used to trigger the chemical reaction that causes the liquid resin to solidify.

Here is how the stereolithography process works, step-by-step:

1. Design Creation: A digital 3D blueprint is created using computer-aided design (CAD) software and converted into an STL file.
2. Preparation: The file is loaded into the SLA 3D printer’s software, which slices the model into thin, horizontal cross-sections.
3. Resin Exposure and Curing: The build platform submerges into a vat of photopolymer resin. A UV laser then moves across the surface of the resin, tracing the design as directed by the printer’s software.
4. Layering: Once the first layer has cured (hardened), the build platform shifts, and the process repeats. This continues layer-by-layer to gradually build the three-dimensional object.

The SLA 3D print is then cleaned and inspected, and may be post-cured to ensure it is fully hardened. A range of post-processing techniques may be used to achieve the desired finish, such as sanding, painting and water sealing.

When Was Stereolithography Invented?

The story of stereolithography starts in 1981, when Japanese researcher Dr Hideo Kodama invented the concept of using a laser beam to cure resin. Dr Kodama published a paper outlining a functional rapid prototyping system using photopolymers, but he was unable to secure funding to continue his research.

In 1984, inspired by Dr Kodama’s work, an American engineer named Charles ‘Chuck’ Hull patented the first 3D printing process and coined the term stereolithography. He also developed the STL file format, which is still used in SLA 3D printing to this day.

After his patent was approved in 1986, Hull founded the company 3D Systems, which went on to produce the first commercial 3D printer in 1988. Hull’s ideas marked a significant advancement in manufacturing technology – he is often described as the father of 3D printing.

What Is Stereolithography Used For?

Today, SLA 3D printing is popular among manufacturers due to its high accuracy and fast production times. It can produce incredibly detailed, complex parts with impressive precision, and at speeds that were previously impossible. Two of the most popular uses for SLA include:

• Rapid prototyping: The speed of SLA 3D printing means that functional prototypes can be produced in record time, allowing for more thorough iterative testing and faster product development.
• Low-volume production: Unlike traditional manufacturing methods, SLA requires no expensive moulds or tooling. This makes it more cost-effective when it comes to producing small product batches or single custom parts.

Designers can choose from a range of resins for 3D printing SLA, allowing them to tailor the properties of the prototype or product according to their needs. Materials may vary in toughness, strength, flexibility, thermal resistance, opacity and more. Their qualities can also be altered through post-processing, e.g. by adding a waterproof coating.

Industrial Applications of Stereolithography

The speed and cost-effectiveness of 3D printing, along with the unique qualities of SLA printed parts, means that stereolithography has industrial applications in many different sectors. It is often used to produce:

• Prototypes
• Concept models
• Tooling aids
• Investment casting patterns
• Jigs and fixtures

Some SLA 3D printing materials are also biocompatible and sterilisable, which means the technology is popular in medical applications. Surgical planning models, custom dental aligners, hearing aids and prosthetics are some examples. The bespoke nature of medical devices makes SLA a great fit, as each item can be customised to a particular patient’s specifications.

Why Choose LPE for SLA 3D Printing?

If you are looking for a fast, accurate SLA 3D printing service in the UK, LPE can help. Our engineers have over 30 years’ experience in producing high-quality 3D printed parts for a wide range of industries, from architecture to healthcare.

We are committed to providing a personal, tailored and professional service, offering a complete range of in-house services and material options. Our processes are ISO9001 and ISO13485 quality assured, guaranteeing consistency and excellence for every customer.

Contact LPE to learn more about our services and discuss your requirements with our friendly team. Alternatively, request a quote for your next project today.