Designing a 3D print assembly

Designing a 3D print assembly

There are many options for designing a 3D printed assembly. Learn about how to apply some of the most common ones to your designs.

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One of the many ways in which 3D printing is revolutionizing manufacturing lies in its remarkable power to help minimize product assembly time, offering you potential time and cost savings.

This is especially true when you apply the principles of integrated assembly to reduce the steps needed to make a 3D printed part. With integrated 3D print assembly, you save time and money by designing a 3D printed part with elements that can be printed in one go.

Chains and interlocking parts, gearboxes, and wrenches can all be 3D printed using the integrated assembly principle.

This article offers an overview of some of the types of 3D printed assembly and some factors to consider when applying to your designs.

3D printing hinges

There are several different kinds of hinges that can be 3D printed as a single assembly. The important thing to bear in mind is that there needs to be enough space around the interconnecting pieces when you print to make sure they don’t fuse together.

Different hinge designs demand more or less space. Those that require more space are usually looser than others.

Scaling hinges

The two hinges illustrated below are very similar in that they have two pieces that connect to an object on the left and a middle piece that connects to an object on the right. Also, they have a rod that goes through the centers of the hinge pieces and gaps at each end.

But, because it has the hinge on the left, the middle piece rotates around the rod, as do the pieces connecting to the left. For the hinge on the right, the rod and middle piece are one solid element, so only the top and bottom parts of the hinge rotate around the rod.

This means that the second hinge wobbles less because it is one part and there’s no space between the middle piece and the rod.

Examples of hinge design strategies

Living hinges

A living or integral hinge is a thin, flexible hinge made from the same material as the two rigid pieces it connects.

To design and print flexible parts successfully, it’s essential to have an appropriate wall thickness, to maintain the curves and angles of folded hinges when converting the model to mesh, and to specify the print orientation.

With HP Multi Jet Fusion (MJF), you can print a finitely flexible part by adjusting its wall thickness and geometric structure. A thin and folded section performs like a living hinge, and allows 3D printed parts to be collapsible and expandable to a certain degree.

An array of living hinges, collapsible by hand

Tube with cosine-curve shaped walls

Accordion structure composed of a number of connected plates

Even a difference in wall thickness of 0.1 mm has a great impact on the degree of the part’s flexibility. Also, if the walls are too thin, the part will not survive cleaning and sandblasting.

You should experiment with varied and controlled wall thicknesses to find the suitable resilience and robustness that suits the purpose a 3D printed part is intended for.

Geometry of structures

The structural geometry of a 3D printed part controls its mechanical behavior when you apply outside force.

Different folding designs can be applied to create specific effects, such as springy tension or smooth motion with the shape and tightness of the folding having a direct impact on a 3D printed part’s movement.

You should make the apex of the fold hinge slightly rounded to avoid the risk of it being snapped when the printed part is stretched or pressed.

V-shaped connectors create springy tension in the folds

Cosine curve shaped create smooth motion

The highly dense mesh applied to the accordion structure maintains the folds´roundness

3D printed assembly: Chains

With powder-based 3D printing, chains can be printed in one go as long as they’re designed with sufficient gaps to prevent accidental fusing or binding.

Example of basic links

Ensure sufficient gaps to prevent accidental fusing

Because 3D printing is so adaptable, chain links can be infinitely complex. They can be differently shaped, adorned, and even have additional moving parts. You can also blend different kinds of links or change scales.

This chain link features an opening, which allows the chain to be re-configured after printing, as needed

Textures can be added, such as the fur-like surface on the links above

These rings feature both springs for texture and openings for re-configurability

The disks "riveted" on these links add both acoustic and tactile properties

3D printed assembly: Chainmail

Chainmail is a basic textile-like structure that can be made from interlocked chain links. It was traditionally used for 3D printing armor but is now increasingly used in the fashion industry. With 3D printing, entire sheets of chainmail can be printed at once. They can also be printed and folded to be larger than the print bed.

A basic four-in-one chainmail features four rings interlocking into every one, but there are many different varieties of chainmail that you can learn about in the HP Multi Jet Fusion Handbook.

For every individual ring, four other rings intersect. When designing for powder bed 3D printing processes, like HP MJF, make sure there are sufficient gaps so that none of the four rings intersect with either the base ring or each other.

Ensure sufficient gaps to prevent accidental fusing

Four-in-one chainmail units can be repeated in rows. In the example shown below, the rings are rotated to create a 90-degree angle with one another, as each row is alternatively rotated 45 degrees clockwise or counterclockwise.

This angle can be increased or decreased according to the design.

Chainmail design example

There are many more examples of different types of Chain designs and design tips in the HP MJF Handbook.

Part consolidation case study:


At HP, we’re pioneering the use of MJF 3D printing technology to streamline processes throughout our own supply chain.

Our supply chain and engineering teams have identified myriad opportunities where 3D printing with HP MJF can replace traditional manufacturing methods. For example, in the drill extraction shoe in HP’s printhead manufacturing line.

The nozzles of HP printheads are manufactured using a laser-cutting process that uses water to prevent overheating of the laser and the silicon plates. A drill extraction shoe is used during cutting to remove the silicon sludge and water that is produced by the laser-cutting process, making it more efficient.

For the process to work as well as it should, an extraction pressure of between ~3 to 4.5kPa is needed, along with a clean extraction shoe. The shoe must also withstand a certain amount of heat caused by stray laser pulses during the drilling process.

The original computer numerical control (CNC) machined tool, pictured below on the left, is made of seven sub-parts, most of them mechanized from an aluminum block and two of them extruded from aluminum.

The HP MJF redesigned part on the right that performs the same function has been consolidated into a single part.

HP MJF helped enable:

  • Manual assembly reduction by consolidating seven sub-parts into one single part
  • Lead-time reduction from 3-5 days with CNC machining to just 24 hours with HP MJF
  • The water tightness required for manufacturing aids that contain pressurized fluids, without needing to post-process or coat the parts
  • The design is to be optimized to reduce turbulence in the part using finite element analysis. The shape of the end of the pipe has been modified to optimize the flow during the section transition

Cost reduction of 95% versus the original part¹
Weight reduction of 90% versus the original part thanks to topology optimization and material reduction²

Find out more about how HP MJF could benefit your business with innovative applications.

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Footnotes and disclaimers

  1. Cost reduction data according to HP: Cost per part: CNC machined $450. HP MJF $18.
  2. Weight reduction data according to HP: CNC machined part weight 575 g. HP MJF part weight 52 g.