In the world of making new products, there's often a big gap between a computer design and a real object that truly shows what you want to create. Making test models that not only look right but also feel like the final product is always a challenge. This is where PolyJet technology finds its special place. It gives us a way to make amazingly realistic models with multiple materials and full color, with speed and accuracy that helps innovation move faster.
PolyJet is an industrial 3D printing method that builds objects by spraying tiny layers of liquid plastic onto a build tray and instantly hardening them with ultraviolet (UV) light. Think of it like a super-precise 2D inkjet printer, but instead of printing ink on paper, it builds 3D objects layer by layer. This method allows for incredible detail and the ability to use many different materials. In this guide, we will explore exactly how PolyJet works, its special materials, main advantages and limitations, how it compares to other technologies, and its most important uses in 2025.
The Core Technology
To really understand what is polyjet 3d printing, we need to look at how the process works. From the user's point of view, the workflow is very smooth and computer-controlled, turning a CAD file into a real part with amazing accuracy. The magic happens inside the machine, where several key parts—print heads, liquid plastic resin, UV lamps, and the build platform—work together perfectly. The process also involves spraying two types of material at the same time: the main model material that forms the part, and a separate, gel-like support material that holds up overhanging features and gets removed later.
The Step-by-Step Process
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Software Preparation: The process begins with your 3D CAD file. Once you load the file into the printer's software, you'll position the model on the virtual build tray, select materials, and decide where they go. The software then slices the digital model into extremely thin horizontal layers, often just tiny fractions of a millimeter thick.
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Material Spraying: The process starts as the print head assembly, which contains hundreds of tiny nozzles, moves across the build platform. Much like an inkjet printer, it carefully sprays microscopic droplets of liquid plastic resin exactly where needed for that specific layer. If the part needs multiple materials or colors, different print heads will place the corresponding resins in the same pass.
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Instant Hardening: Right behind the print heads are powerful UV lamps. As the light passes over the freshly sprayed layer of resin, it immediately hardens and solidifies it. This instant hardening means the parts are fully solid as they are built, layer by layer.
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Layer-by-Layer Building: After a layer is completed, the build platform lowers by a fraction of a millimeter—the thickness of one layer. The print head then moves across again, spraying and hardening the next layer on top of the previous one. This cycle repeats hundreds or thousands of times until the entire object is fully formed.
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Support Removal: Once the print is finished, the part is removed from the build platform. It is covered in the waxy, gel-like support material. This support is easily removed, typically with a high-pressure water jet or by dissolving it in a simple cleaning solution, revealing a smooth, finished part.
The Magic Ingredient
The flexibility of PolyJet comes from its materials. The technology uses photopolymers—liquid resins that are designed to solidify when exposed to UV light. This property makes them perfect for the spraying and hardening process. The real power, however, lies in the huge variety of photopolymers available and, most importantly, the ability to combine them within a single print job.
Primary Material Families
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Rigid Solid Materials: Often part of the Vero family, these materials are the workhorses for creating prototypes that look and feel like production plastic. They offer excellent detail, dimensional stability, and a smooth finish. Importantly, they are available in a wide range of colors, including cyan, magenta, yellow, black, and white, which can be mixed to create thousands of shades.
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Transparent Materials: Materials like VeroClear and RGD720 are used to copy transparent plastics such as PMMA or glass. They are ideal for creating prototypes where viewing internal components is necessary, such as fluid analysis, light guides, or clear cases for consumer electronics. These can also be combined with colored materials to produce tinted see-through parts.
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Rubber-like Materials: The Agilus30 family and similar materials are designed to copy rubber. They are available in various hardness values, from soft and flexible to firm and tear-resistant. This makes them perfect for prototyping gaskets, seals, living hinges, soft-touch grips, and any other application requiring flexible properties.
Digital Materials
This is the key difference for PolyJet. Digital Materials are not pre-mixed resins you load into the printer. Instead, they are composite materials created on the spot, inside the printer, by spraying two or three base resins in specific combinations and amounts at the droplet level. This unlocks a massive range of possibilities:
- Custom hardness values: By mixing a rigid material and a flexible material, you can create dozens of intermediate flexibility levels, precisely tuning the feel of a part.
- Varying shades of color: Combining colored resins allows for the creation of full-color models with gradients and textures, perfect for hyper-realistic color, material, and finish prototypes.
- Copying overmolding: A single part can be printed with rigid sections and soft-touch, rubber-like areas in one continuous build process, perfectly copying an overmolded product without any assembly.
PolyJet's Edge
Designers and engineers choose PolyJet when specific project outcomes are most important. The technology's core strengths directly address the need for realism, complexity, and speed in the product development cycle.
Unmatched Realism
The ability to print in ultra-thin layers, some as fine as 16 microns, results in an incredibly smooth surface finish that closely resembles injection-molded plastic. This reduces the need for sanding or other manual post-processing, allowing teams to evaluate the aesthetic and ergonomic qualities of a part straight from the printer.
Multi-Material Printing
This is arguably PolyJet's most significant advantage. The capability to create a single part with mixed properties—combining rigid, flexible, and transparent components—is a game-changer. A full color, material, and finish prototype can be produced in one print, giving stakeholders a real model that looks and feels exactly like the intended final product.
Exceptional Accuracy
PolyJet printers deliver high-resolution parts with exceptional dimensional accuracy, typically within a tolerance of 0.1-0.3 mm depending on part geometry and size. This precision allows for the creation of intricate geometries, fine text, and complex internal features that other technologies might struggle to reproduce faithfully.
Speed for Prototypes
While not always the fastest 3D printing process in terms of raw build volume per hour, PolyJet is exceptionally fast for producing high-quality, multi-material models in a single, unattended run. This ability to combine what would otherwise be a multi-part, multi-process assembly into one print job dramatically speeds up the design verification and iteration cycle.
A Balanced View
To make an informed decision, it's important to understand where PolyJet excels and where other technologies might be a better fit. No technology is perfect for every application, and PolyJet has specific considerations to keep in mind.
Mechanical Properties
While excellent for visual and touch prototypes, standard PolyJet photopolymers are generally more brittle and have lower heat resistance than production-grade thermoplastics like ABS, PC, or Nylon. They are typically not suited for rigorous functional testing that involves high stress, impact, or fatigue.
Cost of Operation
PolyJet is an industrial-grade technology, and this is reflected in its cost. The initial equipment investment is significant, and the proprietary photopolymer resins are more expensive per kilogram compared to filaments used in FDM or powders used in SLS. This tends to result in a higher cost per part.
UV Sensitivity
As photopolymers, parts produced with PolyJet can be sensitive to prolonged exposure to sunlight or other UV sources. Over time, this exposure can cause the materials to change color, become more brittle, or alter their mechanical properties. Additionally, the workflow requires a post-processing step to remove the support material, which, while straightforward, adds time to the overall process.
PolyJet vs. Others
Choosing the right 3D printing technology depends entirely on your application's primary requirement. Is it strength, surface finish, material complexity, or cost? The table below provides a practical comparison for making that decision in 2025.
Comparison Table
| Feature | PolyJet | SLA (Stereolithography) | FDM (Fused Deposition Modeling) | SLS (Selective Laser Sintering) |
|---|---|---|---|---|
| Primary Principle | Material Spraying | Vat Hardening | Material Melting | Powder Bed Fusion |
| Surface Finish | Excellent | Very Good | Fair/Good | Good |
| Resolution/Detail | Excellent | Excellent | Good | Very Good |
| Material Variety | Excellent (multi-material) | Good (resins) | Excellent (thermoplastics) | Good (polymers) |
| Mechanical Strength | Fair (for prototyping) | Fair-to-Good | Good-to-Excellent | Excellent |
| Cost per Part | High | Medium-High | Low | Medium-High |
| Best For | Hyper-realistic prototypes, medical models, overmolds | Fine-detail prototypes, casting patterns | Low-cost prototypes, functional parts | Durable functional parts, complex geometries |
Where PolyJet Shines
The true value of what is polyjet 3d printing is realized in applications where realism and material complexity provide a distinct advantage. In 2025, its use cases are more advanced and integrated than ever before.
Advanced Prototyping
This remains PolyJet's primary application. Imagine a team designing a new high-end coffee maker. They can print a single model that features a rigid, glossy black body, a clear water reservoir, and soft, rubber-like buttons. This color, material, and finish prototype allows them to evaluate aesthetics, ergonomics, and assembly fit long before committing to expensive production tooling.
Medical and Dental
The medical field heavily relies on PolyJet for its accuracy and material variety. For example, a medical device company in 2025 developing a new surgical tool can use PolyJet to print a model combining a rigid, colored handle with a clear section to show internal mechanisms and a soft, rubber-like grip. This allows surgeons to provide immediate feedback on ergonomics and function. It's also widely used for creating patient-specific anatomical models from CT scans, where different colors and materials can differentiate bone, muscle, and vascular structures for surgical planning.
Jigs and Fixtures
On the factory floor, speed and customization are key. PolyJet is used to rapidly create custom jigs and fixtures for assembly lines. The ability to incorporate soft, non-scratching surfaces or ergonomic grips directly into a rigid tool improves both worker comfort and production quality.
Low-Volume Injection Molds
Using advanced, high-temperature digital materials, companies can 3D print molds for short-run injection molding. This is a powerful application for producing 10 to 100 parts in a final production thermoplastic. It drastically cuts tooling time from weeks to days, enabling pilot runs and market testing with production-grade parts at a fraction of the traditional cost.
The Future of PolyJet
PolyJet technology is far from static. As we look beyond 2025, several key trends are shaping its future, pushing it further from a prototyping tool toward a viable manufacturing solution. Market analyses project strong growth for the photopolymer spraying sector, with its market value expected to increase substantially by 2030, driven by innovations in materials and software.
Material Breakthroughs
Research and development are intensely focused on expanding the material portfolio. We anticipate the arrival of more durable, engineering-grade resins that better copy the strength and longevity of production plastics. Furthermore, progress in biocompatible materials for direct-use medical devices and more sustainable, recyclable photopolymers will broaden its applications.
Software, AI, and Automation
The integration of artificial intelligence is making the workflow smarter. AI algorithms are being developed to automatically optimize part orientation, generate the most efficient support structures, and minimize material consumption. On the hardware side, increased automation in post-processing, such as hands-free support removal systems, will further streamline the process from file to finished part.
Expansion into Manufacturing
While prototyping will remain a core strength, PolyJet is increasingly being adopted for end-use parts. In industries where customization and aesthetic quality are critical—such as consumer goods, audiology, and luxury items—the ability to produce small batches of highly complex, multi-material parts makes PolyJet an attractive option for final production.
Is PolyJet Right for You?
PolyJet has firmly established itself as an essential tool for professional designers and engineers. Its identity is defined by three pillars: unmatched realism, multi-material capability, and high-precision accuracy. It bridges the gap between digital concepts and physical reality like no other technology.
When deciding if it's the right fit for your next project, consider these simple guidelines.
Choose PolyJet if your priority is:
* The highest possible realism and surface finish.
* Creating parts with multiple materials, colors, or flexibility levels in a single print.
* Verifying the look, feel, and ergonomics of a final product.
Consider other technologies if your primary need is:
* High mechanical strength and durability for functional testing.
* The lowest possible cost per part.
In the fast-paced landscape of modern product development, the ability to quickly and accurately validate a design is a significant competitive advantage. PolyJet provides exactly that, cementing its role as a cornerstone of the professional 3D printing ecosystem.