Quick guide on multicolour 3D printing & How it works

3D printing generally uses single colour in its model. Some 3D printing technology is limited to use only one colour because of the difficulties associated with getting multi-colour output using a filament or resin. Moreover, major issues were identified such as the difficulty of using single strands of filament.

As a result, question such as “Is it really possible to print 3D objects in multicolour?” may arise. To understand more about multicolour 3D printing, here is a quick guide to multicolour 3D printing and how this technique works.

What is multicolour 3D printing?

Multicolour 3D printing is a process wherein prototypes are printed in more than one colour. With this method, colours are directly applied to the object while it is printed. It also allows colour combinations with several coloured materials.

There are specific materials that are compatible to be printed in multicolour. For now, the only material that can be used for a full-colour 3D model is the composite material. This type of material resembles a sandstone.

The importance of creating prototypes is known by many designers and manufacturers nowadays. Printing in multiple colours can help them create detailed models that are more usable. It also makes printing process efficient and reduces the number of necessary post-processing steps.

Advantages

In multicolour 3D printing, manufacturers can create aesthetic objects. It also gives them freedom to creatively change the object’s tints, colour and shade. Although you can paint the 3D model after printing, multicolour 3D printing is faster and can provide more accurate results.

Drawbacks

Multicolour 3D prints are highly fragile. Thus, most of these items are destined to be used as an ornamental. It has also a lower dimensional accuracy compared to SLA (Stereolithography) or SLS (Selective laser sintering). Moreover, colour consistency is difficult to achieve.

What is the 3d printing technology used?

Today, desktop 3D printers such as FDM printers have limited capabilities when it comes to multicolour printing. This is because these printers have single extruder and it is a challenge to work using many colours. For others, one possible option is to pause the printer, change the filament and restart the printing process. This is the so-called “change colour” option that is built in some firmware printers.

Multicolour 3D printing can be done in 3 printing technologies. These are Selective Deposition Lamination (SDL), Binder Jetting and Polyjet Technology. The most common technology used when it comes to 3D printing is Binder Jetting

There are different techniques on how to add different colours to 3D models. Here are some of them.

Techniques of adding colour to 3D models (how it works)

• Printing objects separately

One of the most inexpensive ways of adding colour to 3D prints is to print the objects separately. In this option, a single CAD model is broke up into individual components based on its colour.

This technique requires a lot of pre-processing methods and needs to be precise in order to achieve well-defined results.

One of the advantages of this option is that it is accessible for desktop users since it only requires one extruder. Moreover, if there are any errors on the individual parts, it can be reprinted separately.

The only downside of this method is that it requires a great amount of work before printing. Aside from breaking the model into separate components, post-processing is also needed for each individual part before assembling the whole model.

• Pausing mid-print

This method is almost the same as the first one as it involves using multiple colours and a single extruder. However, the only difference is that it does not require a lot of pre-processing and the end result is only the single model.

In this technique, the printing process is paused or stopped midway through to change the filament feeding into the extruder. This technique requires a lot of patience since the printing process must be paused manually. You should also need to make sure that there are no leftovers of the previous colour in order to have a smooth changeover.

• Printing with multiple nozzles

This technique is somewhat more advanced compared to the first two methods. It is similar to the standard desktop 3D printer which uses Fused Deposition Modelling (FDM) technique. Instead of using a single nozzle, separate nozzles for each spool filament is added. Typically, two to five nozzles are added which can print as many colours depending on the available nozzles.

Instead of changing the spools of filaments manually, G-code command controls the changing of colours. Conversely, there is one noticeable drawback of this technique. It requires more space since extra nozzles are used.

In this case, the available space for printing shrinks. Furthermore, it is difficult to calibrate the nozzles on all three axes.

• Using one nozzle with multiple spools of filament

Since some printing companies avoid the use of multiple nozzle methods, they have created 3D printing machines that feed multiple spools into a single nozzle.

There are a few advantages to this technique. First is the printable area does not shrink. There are also no calibration issues for this method. Also, it ensures good result. Nevertheless, it still has difficulties when it comes to colour transitions and providing true full-colour 3D printing.

• Non-extrusion based methods

This technique is an entirely different method since it works closer to a traditional 2D inkjet printer. It works by laying down thin layers of sandstone powder or liquid plastic using PolyJet technology.

When using full-colour sandstone 3D printing, the machine applies colour to each layer and binds it together until the model is completed. For PolyJet printing, liquid photopolymer material is used. The photopolymer will undergo curing using UV light to form a model.

Although PolyJet printer is very expensive (machines typically cost around $200,000), you can certainly produce full-colour models with colour gradients.

Conclusion

3d printing in multicolour is not only useful to creating artistic ornamental objects but also beneficial in fields such as in medicine, architecture, etc.

Multicolour 3D printing can be a difficult technique. It can also be time-consuming especially for 3D parts that have fine details. However, as 3d printing technology improves, designers and engineers can discover ways on how to develop multicolour 3D printing.

If you want to outsource 3D printing services, look for a supplier that has the ability to print not only monochrome models but also the multi-coloured ones.