What is the Strongest Infill Pattern?

Infill patterns are often an overlooked stage in 3D printing as people often think about the aesthetic rather than the overall strength of the product.

It’s more than just the pattern itself however as infill patterns indicate the density which is the amount of filament printed inside the object.

This then relates to the strength, weight and printing time which can have a massive impact on the performance and result of your project.

Depending on what you are working on, the infill pattern can have a positive or negative impact on your project. 

It cannot be understated how important it is to research various infill patterns so you can be better informed on what pattern works best for your projects and give you a result that is durable and the highest quality.

So which infill pattern is the strongest and best to use?

Naturally, this is dependent on your 3D printer on the whole but the most popular and trusted design is the honeycomb pattern thanks to its supported structure and ability to fill the whole project.

You want to ensure that the rectilinear pattern is enforced as this will align with the direction of force but be aware that when facing the opposite direction, it can become weak due to the resistance.

Although the honeycomb pattern is the most popular, this doesn’t necessarily mean that it is the best infill pattern for all projects and that is where this guide comes in. We will discuss various infill patterns and where they are best suited due to their functionality.

By the end of this guide, you’ll have a well informed understanding of why the infill pattern is important and which one you should be choosing for your projects.

As mentioned before, the strongest infill pattern to choose is a rectilinear pattern which has an incredible tensile strength value of 36.4 Mpa when using 100% infill.

The likelihood is that you won’t be using 100% infill but the effectiveness of these patterns should not be overlooked. It does have its weaknesses in that it is weak when faced against the direction of force so needs to be handled with care.

When compared to the honeycomb infill pattern, rectilinear uses less plastic and prints 30% faster than a honeycomb pattern so it is ideal for those who want to use as little materials as possible and have a quicker printing time.

When it comes to considering what the best all round infill pattern is then honeycomb is the best option.

Often referred to as the cubic pattern, this pattern is the most popularly used infill pattern available thanks to its various qualities and characteristics that make it appealing for a variety of different projects.

When compared to rectilinear patterns, honeycomb is weaker in the direction of force but it has an equal amount of strength in every direction meaning that it is more reliable overall. The honeycomb pattern is equal throughout and is a lot more supported than the rectilinear pattern.

Although aesthetics are not a priority, the honeycomb pattern looks more professional and sleeker in its finish and its application has been used in a variety of industries including aerospace because of its unique structure.

The aerospace industry uses the honeycomb infill because of the manufacturing process involved but if they were basing it on strength then the rectilinear would be the best choice. The honeycomb infill is more accessible given the resources and more supported throughout the pattern.

Depending on the materials used, certain infill patterns may not be as forgiving and thus affect the final result as well as the performance whilst printing is taking place. For example, honeycomb takes a longer time to print because of the amount of movement that is involved and the intricacy of the pattern.

To give you a better understanding and idea of how much infill should be used and the pattern, there are more consistent results when using a linear or diagonal pattern due to the fact that they provide more support.

For those who want to use infill percentages then it doesn’t matter if you choose linear, diagonal or honeycomb patterns but bear in mind that honeycomb is slower and it is advised to use it at a higher infill percentage due to the detail in this pattern.

On the other hand, those who wish to use a higher infill percentage will find comfort in using diagonal patterns which is an average of 10% stronger than linear or hexagonal patterns.

What are the strongest infill patterns?

Infill patterns can either be 2D or 3D depending on the design. A lot of hobbyists tend to opt for 2D infills because they provide a decent print although a lot of them do produce weaker models when compared to 3D infills.

There are some strong 2D infills which we will discuss in this section, however, that should be considered if you are a fan of 2D infill.

3D infills not only provide more strength to your projects but their structure allows the print to be supported in all directions of force meaning that your products will be more durable in the long run.

They do take more time to print and more materials but the mechanical strength of your models is worth it. 3D infills are advised for those who are making functional prints and want their product to have longevity and reliability.

What infill patterns are available is dependent on your printer and the software you are using, however, the average patterns should be available. If you see that your printer or software has some custom patterns installed then it may be useful to consider using that and balancing out the functionality of it.

The strongest 2D infill patterns are the grid, triangles and tri-hexagon. Each of these patterns are very different in their aesthetic but they help to give basic support to your prints.

If you are making smaller products with limited functionality then these patterns can help give a solution that takes limited time and less materials.

Overall, this option is convenient and cost effective but should only be used on products that are not designed to endure heavy use.

For those wanting to use a 3D infill pattern, it is advised to use a cubic, cubic subdivision, octet or quarter cubic patterns. All of these have strong, distributed support that will provide the durability and longevity of your prints.

Cubic subdivision is a particularly good pattern for those who want a fast printing time. It has strength in 3 dimensions as well as long straight printing paths which provides it with quicker infill layers, giving long lasting support to your print.

Lastly, for those making functional products that require an increased weight then gyroid and rectilinear are the infill patterns that you should consider.

Providing high strength at a lower weight, these are intricate prints that require a high infill pattern and can take its time to print but will provide products that have a higher durability than other 3D infill patterns.

As gyroid is a complicated pattern, it can take a while of trial and error to find what the best infill density for you is. If you select a low infill density then you may experience some issues in the printing process so make sure you take your time if choosing a gyroid infill.

What is the strongest infill pattern?

After selecting your pattern, the next step is to consider your infill percentage. This is important because it provides the structural integrity of your project.

The easiest way to think about it is how much plastic is going to be inside the print. The more plastic that fills the middle, the stronger it is going to be because there will be more mass and support.

Naturally, the answer is that 100% infill is going to be the strongest infill percentage but you have to think about the printing time and the materials used in the printing process rather than just going ahead and selecting 100%.

On average, 3D printers apply 20% infill density which tends to be the default in the majority of slicer softwares. This is because the majority of products made on 3D printers are made for the aesthetic and are non-load bearing but when it comes to functional prints then you will need to go higher.

If you are creating a functional project that needs a tremendous amount of strength then its best to go for around 50% as this will provide the support you need without overwhelming your project with too much material in its centre.

The difference between 20% and 50% is huge and you’ll notice the difference immediately.

3D Infill Pattern Percentages

Infill percentages range from 20% (left), 50% (center) and 75% (right). Going above 75% is just going to be time consuming and waste materials so shouldn’t really be considered unless absolutely necessary.

If you fill your print with too much material, it can affect the overall weight and make your projects heavy which may increase the chances of breakage and damage in the long run.

It’s advised not to go above 50% because this will provide the perfect balance between support and overall performance.

What is the quickest infill pattern?

For those who want a quick and easy infill pattern then the simple lines pattern is the one that you should go for.

A lot of times, this pattern is the default pattern set in many printers and software because of its popularity.

Although it has a decent amount of strength and uses less material than most patterns, there are many better options out there.

However, for those where time is paramount then the lines pattern is the route you should go down as it is the fastest infill pattern you can use other than avoiding an infill pattern at all.

What makes 3D infills strong?

What makes the 3D infill strong is the support they provide to the interior of the prints. As mentioned previously, they have a huge impact on the strength and durability of the product.

Not only will it make it harder to break the product, but it will also enhance the overall appearance and quality, allowing you to experiment with which infill pattern works best for you.

Products such as the Smooth-On XTC-3D High Performance Coating allows you to make your products even stronger as well as giving it a smooth finish.

This is great for those who want to make professional products to sell as they will look more consistent and bring extra strength by adding an extra coat on the outside.

Filament Quality

It’s important to know that not all filament is made from the same quality materials.

You want to ensure that you are purchasing your materials from a reputable brand to ensure that your results are sleek and professional, providing the durability and longevity of the product.

Filament from reputable brands can be more expensive but this is worth it in the long run as the results will differ significantly than using cheaper filament that is likely to break or damage the print.

Filament Blends and Composites

Filament has been developed over the years to have more endurance thanks to the stronger materials.

The usual filament will be made from PLA but you can purchase some PLA plus or PLA that has been blended with other strong materials such as wood, carbon fibre or copper among others.

Figure out what you want to get from your projects and purchase accordingly. This will ensure that you manage your expectations.

Print Orientation

This step is often overlooked but this can also assist in strengthening your prints. The layer lines of the prints are always the weak points of the product.

Try to adjust the printing orientation of your project to see how the results differ and how this affects the overall strength.

Even rotating the print part 45 degrees can more than double your strength. This can be time consuming and use a lot of excess material but if you don’t mind this then it will help you to understand how moving the orientation of the print can cause a huge difference.

Number of Shells and Perimeters

The shells of the print are the outer parts of the model which outline the perimeter of each layer. They simply number the layer on the outside of the print.

These have a huge impact on the part strength as one extra shell could provide the same extra strength as an extra 15% infill. In the long run, this can help to use less materials.

On the other hand, shells are an extra part of the project to print so this will increase the overall printing time so there is a downside to going down this route.

Shell Thickness

You can adjust the shell thickness according to your preference as well as adding them. This can mean that you can have thicker shells without adding lots of extra ones. Where adding shells can increase printing time, this is a great alternative to avoid this.

The thickness is adjusted when the parts have to be sanded down or post processed as it can wear the part away. In order to avoid any disfiguration, a thicker shell will allow you to sand down your print without suffering any drastic problems.

To avoid imperfections, the thickness of the shell is calculated at a multiple of the nozzle diameter. This will help your print to look in shape before being sanded down.

You do have to consider the number of the walls and the wall thickness before deciding what you should adjust the thickness to.

Over Extruding

Over extrusion can help with strength but can have an affect on the aesthetics and precision of your print.

On average, 10% to 20% of over extrusion will increase strength but there may be a reduction in the overall look.

To experiment with over extrusion, it’s best to take part in trial and error so you can see what works for you and your projects.

Smaller Layers

Smaller layers are beneficial because they provide more intricate support. Having large layers will take less printing time but won’t provide the same amount of strength and support.

The downside to smaller layers is that it can take double the printing time overall as you will have to switch from a 0.4mm nozzle to a 0.2mm nozzle.

Decide on what size layers you want to use after you have considered the infill pattern and percentage as these can determine a suitable layer size for you to try.

Once you have combined all of these factors, you’ll be able to create prints that are durable and reliable whilst also providing the longevity you need. 

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