What is Vat Photopolymerization?
A Guide to the process and its most common forms

1. Preparation of the Design: A digital 3D model is designed using CAD software, while slicing software guides the printer during the printing process.
2. 3D Printer Setup: A photopolymer is chosen according to the desired properties (e.g., flexibility, durability). The vat printer is calibrated, including proper levelling of the build platform and resin temperature adjustment if required.
3. Filling the Resin VAT: The vat is filled with liquid photopolymer resin. The resin must remain uncontaminated and free of bubbles.
4. Light Curing Layer by Layer: A light source selectively cures the resin layer by layer. The resin in the exposed areas solidifies.

5. Layer-by-Layer Repetition: After each layer is cured, the build platform moves slightly, allowing fresh resin to flow over the cured layer. This step is repeated until the entire object is formed, with each layer bonding seamlessly to the previous one.
6. Post-Printing & Post-Curing: The printed object is detached from the build platform and uncured resin is removed. The object is placed in a UV curing chamber to complete the polymerisation process.
7. Finishing: The surface can be further polished, painted and coated to improve aesthetics.

LCD

For low to medium-volume production, Liquid Crystal Display (LCD) printing offers an excellent entry point into Vat photopolymerisation. It uses an LCD screen to selectively block or transmit UV light, curing the resin layer by layer. The screen works in tandem with a UV light source to create patterns that solidify the material.

LCD printing is often favoured for desktop 3D printers due to its affordability and accessibility. It provides good resolution, which makes it suitable for hobbyists and small businesses without the higher costs of SLA or DLP systems. While LCD printing is efficient and budget-friendly, it can have limitations in durability and print consistency.

DLP

Digital Light Processing (DLP) is a faster alternative to SLA, using a digital projector to cure entire layers of resin simultaneously. Instead of tracing each layer with a laser, the projector flashes a pattern of UV light onto the resin surface, curing it in one go.

DLP printers are well-suited for creating small to medium-sized objects with high resolution. The speed of the process makes it advantageous for time-sensitive projects, such as rapid prototyping. DLP also offers excellent detail quality, comparable to SLA.

One limitation of DLP is that the resolution depends on the size of the projected image. For larger build areas, resolution may decrease because the same number of pixels must cover a broader surface.

SLA

Stereolithography (SLA) is the original 3D printing technology, introduced in the 1980s. It uses a UV laser to selectively cure liquid resin into solid layers. The laser traces the design of each layer directly onto the resin surface, solidifying the material in precise locations.

SLA is renowned for its exceptional precision, achieving resolutions as fine as 25 microns. This high accuracy makes it ideal for applications requiring intricate details, such as jewellery, dental moulds, and medical devices. The smooth surface finish of SLA-printed parts also reduces the need for extensive post-processing.

Vat photopolymerisation materials differ depending on the process. Each resin type is formulated to optimise performance for its respective printing process.

SLA supports a broad range of resins, including standard resins for general prototyping, tough resins for impact resistance, flexible resins for elastomeric properties, high-temperature resins for heat resistance, and biocompatible resins for medical and dental applications.

DLP, known for its speed and detail, works with standard, rigid, transparent, and castable resins, designed to take advantage of its rapid curing capabilities.

LCD technology is compatible with cost-effective resins such as standard and water-washable types, along with more specialised options like tough or flexible resins tailored for small-scale and hobbyist applications.

Can I print with multiple colors or materials using Vat photopolymerization?

Advanced Vat photopolymerization printers can print in multiple colors or materials by swapping resins during the print process. Most consumer-grade printers are limited to a single resin at a time. For multi-material prints, users may need to manually switch resins or post-process prints to add color or texture

Is Vat photopolymerization suitable for prototyping?

Yes, vat photopolymerization is an excellent choice for prototyping due to its high level of detail and the ability to produce complex geometries quickly. It is commonly used in industries like automotive, aerospace, and healthcare to create functional prototypes for testing and validation.

Are Vat photopolymerization prints durable?

The durability of prints made with Vat photopolymerization depends on the type of resin used. Standard resins are typically more brittle than other materials like PLA or ABS. However, there are ways to reduce brittleness of 3D resin prints, adding higher durability, flexibility, or impact resistance.

Can Vat photopolymerization be used for large-scale prints?

While Vat photopolymerization is great for high-detail prints, it is typically not the best method for large-scale objects due to size limitations of the print bed and slower print speeds. Large prints may require multiple pieces to be printed and then assembled.
 

What types of products are best suited for Vat photopolymerization?

Vat photopolymerization is ideal for creating highly detailed, small to medium-sized objects, including jewelry, dental models, orthodontic devices, prototypes and concept models as well as custom parts for engineering and design, just to name a few.