In the world of additive manufacturing, while many technologies focus on strength, metal parts or functional performance, CJP 3D printing stands out as the specialist for full-colour, visually rich 3D models. Whether you’re a designer needing realistic concept models, an architect building presentation pieces, or an educator seeking detailed visual aids, understanding the CJP process gives you the ability to choose it intelligently, optimise your designs for it, and get better cost and time outcomes.
Let’s break down the complete CJP 3D printing process step-by-step from the digital model to a finished full-colour model and explore its advantages, limitations, and best-use cases.
What is CJP 3D Printing?
CJP (ColourJet Printing), also known as ColourJet Printing or simply “CJP printing”, is a 3D printing technology that uses a powder bed base material (often gypsum- or plaster-based, or specially formulated polymer-powder) combined with a binder that is selectively jetted through inkjet print heads. The binder may carry colour (typically CMY or CMYK) and/or adhesive to fuse the powder particles layer by layer.
In simpler terms: think of the process like this
- A very thin layer of powder is spread across the build area.
- Then an inkjet print head “draws” the cross-section of your model for that layer, using coloured binder that binds the powder (and gives the colour).
- Then the next layer of powder is spread, and the process repeats until the whole 3D object is built.
- After printing, the part is removed, any loose powder cleaned off, and usually a post-process infiltration is applied to strengthen and finish the piece.
Because CJP can apply full-colour and texture maps directly during printing, it’s extremely attractive for visual models, prototypes and demonstration pieces.
The Core Principle
At the heart of CJP 3D printing technology lie three core ideas:
- Powder bed deposition : Spreading a thin uniform layer of base powder material across a build platform.
- Binder/colour jetting : Ink-jet print heads deposit a binding and/or coloured liquid on specific areas of the powder layer according to the cross‐section geometry and colour/texture data.
- Layer-by-layer stacking : After one layer is processed, the platform is lowered (or next powder layer is added), the next layer is processed, and the cycle repeats until the entire 3D part is built.
Put simply:
Digital model → sliced layers with geometry + colour info → powder spread → binder jets solidify & colour layer → repeat until full part is built.
Because the binder solidifies the powder (rather than melting metal or sintering polymer), the parts can incorporate full-colour textures and visual complexity, but the mechanical strength is more modest compared to structural AM technologies.
The Complete CJP 3D Printing Process
Let’s walk through the full journey of using CJP 3D printing from concept to final full-colour model.
Design the 3D Model
Everything starts with a digital CAD or 3D model (created in software such as SolidWorks, Rhino, Fusion 360, etc.). But when designing for CJP you must think beyond just shape. Key aspects to consider:
- The 3D file must be watertight (no holes, non-manifold geometry) because the powder bed process needs stable geometry.
- Colour/texture mapping: If you want full colour/texture, the model must include UV mapping or colour information so that the binder can deposit correct colours.
- Orientation & build volume: You should scale and orient the model for the build volume of the CJP machine (many have limitations like e.g., 10″×15″×8″ or larger)
- Consider support and stability: Although CJP often does not require separate support structures (because the un-bound powder itself supports the part) you still should avoid extremely thin unsupported overhangs since the green part is fragile.
- Export the model in a suitable 3D print file format, often STL is acceptable, but for full-colour you may need formats that support colour/texture (e.g., VRML, 3MF).
Slicing & Setup for Powder/Binder
In the slicing stage the 3D model is processed into thin layers and the machine tool‐paths:
- The model is oriented for optimal visual result (for example for best texture visibility) and efficient build.
- Since colour and texture are involved, the slicing step will include colour/texture map data so that each layer knows where to deposit colour binder and where not to.
- Key parameters are defined: layer thickness (often ~0.1 mm or 100 µm in many CJP machines).
- The slicing software generates the build job for the machine including binder paths, colour mapping, and support of unbound powder zones.
- The machine setup will also include material settings (what powder, what binder), colour calibration (for full-colour consistency) and any finishing or infiltration steps to be applied post print.
Machine Preparation
Before printing begins on the CJP machine:
- The build chamber is prepared: powder is loaded, roller/spreader system (to spread each layer of powder) is calibrated.
- Print heads (inkjet) for the binder/colour are checked and aligned. The binder cartridges (CMY or CMYK) are loaded.
- Safety protocols: powder handling (especially gypsum-based or polymer powders) may generate dust; proper ventilation and handling are needed.
- Build plate is set up and clearance verified. Some machines may require pre-heating (though typically less critical than high power melting technologies).
- The first layer of powder is spread manually or automatically, ready for binder deposition.
The Printing Process
Here’s the core “CJP 3D printing process” in action:
- A layer of powder is rolled/ spread across the build platform.
- The inkjet print head selectively deposits binder (which may be colour + adhesive) onto the powder layer according to the slice data. This binder binds the powder particles in the areas of the part and deposits the colour/texture.
- After binder deposition, the print head returns, the build platform lowers (or roller spreads next powder layer) and a fresh layer of powder is applied.
- The next layer is processed: binder jets, colour deposition, etc. The binder fuses that layer to the previously bound powder.
- This repeats layer by layer until the full 3D model is built. Because the surrounding un-bound powder supports the model during printing, no extra supports may be needed which speeds up process and simplifies post-process.
- Build time depends on model size, colour complexity (full colour vs monochrome), layer thickness, machine speed. Some machines claim 5–10× faster print speeds than other technologies.
Post-Processing
Once the print job completes:
- The build is removed from the powder bed; loose powder is carefully removed (often by brushing, blasting, vacuum) while preserving the coloured surfaces.
- The part is still fairly fragile in its “green state” (before infiltration) because the binder is relatively weak compared to fully fused parts. The user must handle it with care.
- Often an infiltration fluid (sometimes called “ColorBond” or similar) is applied. This infiltrant penetrates the porous printed part and cures/solidifies, increasing strength, enhancing colour vibrancy, and improving surface finish.
- Additional finishing may include wax coating, clear coating, sanding, painting, or mounting depending on the use case. Some parts can be drilled, tapped, glued as required.
- Final inspection: dimensional accuracy, colour fidelity, surface finish. Because CJP parts are often for visual/communication rather than structural load, aesthetic quality is more the focus than extreme mechanical performance.
Common CJP Materials and Their Uses
Below is a snapshot of typical base materials and common uses in CJP 3D printing :
Selecting the right material depends on your application: do you need full colour realism (CJP shines) or structural strength (maybe another technology). For visual models the powder + binder route is ideal.
Key Parameters That Affect CJP Print Quality
Mastering CJP printing means understanding the parameters that affect visual quality, durability and cost. Here are some of the crucial ones:
- Layer Thickness: Typical layer thickness for CJP is around ~0.1 mm (0.004″) in many machines. Thinner layers yield finer detail and smoother surfaces; thicker layers reduce print time but may degrade detail.
- Colour/Texture Resolution & Binder Drop Size: Full-colour fidelity depends on how finely the binder jets can deposit colour and how the halftoning/dithering is managed. Some machines have high DPI (e.g., 600×540) for great colour gradients.
- Powder Quality & Binder Penetration: Uniform powder grain, consistent density and good binder penetration yield better finish and colour saturation. Poor powder/binder match may lead to weak part, poor colour.
- Build Orientation & Nesting: Because of colour mapping and surface visibility, orientation matters (e.g., more visible surfaces should face out). Also for efficiency you may nest multiple parts in one print job.
- Infiltration and Finishing: Post-process infiltration affects strength, surface finish, colour vibrancy. The infiltration choice (wax vs colourbond vs clear coat) influences durability and appearance.
- Surface Finish & Edge Definition: Because the powder-binder route has inherent porosity (before infiltration) and colour binder may bleed slightly, if you need high gloss, smooth surfaces or fine mechanical features you must plan accordingly (sanding, coating, etc).
- No Supports Required: One of the advantages is that no dedicated support structures are needed in many CJP builds because the powder bed supports the part. This simplifies workflow and reduces finishing.
Advantages of CJP 3D Printing
The benefits of adopting CJP 3D printing (for full-colour models) are clear and compelling:
Full-Colour & Texture Capability
CJP enables the printing of realistic models with colour gradients, textures, logos, skin-tones etc without needing painting by hand.
Fast Turnaround for Visual Models
Because the process is relatively simpler (powder + binder) and no supports are needed, print times can be relatively quick for visual models, enabling rapid concept iteration.
Low Cost for Visual Models
For purely visual/communication models (rather than structural parts), CJP tends to be more cost-effective than high-end structural printing. Some machines claim up to 7× lower cost than other technologies.
Design Freedom for Aesthetics
You can print complex geometries, internal details (if colour/texture is required), and visual differentiation. Because no supports are required, internal features can be freer.
Excellent for Communication, Prototyping, Visualisation
Industries such as architecture, medical models, consumer product visual prototypes, signage/graphics benefit hugely from CJP’s colour and texture ability.
Limitations of CJP 3D Printing
For balance, it’s important to recognise the challenges when using CJP printing:
Limited Mechanical Strength
Despite infiltration, CJP parts are not typically suitable for load-bearing or highly-stressed functional components. They are more for visual/communication use.
Surface Finish & Durability
The surface may be slightly porous or rough compared to fully fused technologies; infiltration helps but may still require post-finishing. Colour binder may be more sensitive.
Colour Fade or Wear
Over time or under certain finishes, colour fidelity might degrade unless properly coated or sealed.
Build Size & Resolution Constraints
While there are large-volume CJP machines (e.g., 508×381×229 mm) the build size may still be smaller than largest structural machines; nesting and orientation are still relevant.
Material & Process Cost for High Volume
While cost per model is lower than some tech for visual models, for very large volumes or functional parts other technologies may become more economical. Also parts may require infiltration and finishing, adding labour/time.
Colour Consistency/Calibration
Full-colour printing demands careful calibration and perhaps specialised software or workflows to match textures, gradients, and expected colour output.
FAQs
Why is CJP 3D Printing preferred for full-colour models?
Because CJP uses a binder jetting process that can deposit coloured binder (CMY/CMYK) onto a powder bed layer-by-layer, it can produce models with realistic colours, textures and detailed surface finishes ideal for visualisation, architectural models, medical models, and consumer product prototypes.
What is CJP 3D printing used for?
It’s ideal for making realistic concept models, prototypes, architectural and medical models, and educational displays where visual detail matters more than strength.
How does the CJP 3D printing process work?
The process starts with a thin layer of powder spread on the build platform. Then an ink-jet print head selectively deposits binder (with colour) to bind the powder in those areas and build the slice. The platform lowers or a new powder layer is added, and the process repeats until the model is complete. After printing, the part is removed, cleaned, and often infiltrated/coated for strength/finish.