One of the benefits of Markforged composite 3D printers is the ability to add reinforcing fibres into a 3D part, providing exceptional strength and functionality to the final part.
However, we have seen our customers using near-solid fibre on their Markforged Continuous Fibre Reinforcement (CFR) parts, where it often isn’t necessary, overly expensive, and can lead to long print times. Customers end up using hundreds of cubic centimetres of fibre throughout their printing when they could achieve similar results with far less fibre. The only difference is with how the fibre is used and where it is placed.
There are a number of ways and tools that can be easily applied to help select the correct amount of fibre required in your part, from settings in Eiger including fibre striping through to new Simulation software (see Blog "Validating Parts Prior to 3D Printing).
In this blog, we carry out an in-house experiment applying different fibre strategies to demonstrate easy-to-adopt fibre settings.
To test and understand the effects of different fibre strategies, we designed a simple ‘S’ hook and then used weights to see the deflection of the part under different loads.
We printed three of these hooks:
1. Onyx only
2. Striped Fibreglass
3. Solid Fibreglass
As we added each weight, we measured the length from the top of the hook to the bottom to see how each hook withstood the added weight.
For all three S hooks, we used the standard Markforged print settings for Onyx, with the only difference being the fibre strategies when it came to the fibre filled parts.
Benefits of applying the correct amount of fibre:
Why did we take time to carry out this experiment and share our learnings? Applying the correct amount of fibre to your part has a number of benefits:
Reduced part cost and material use – Fibre is a more expensive material so reducing the quantity reduces the per part cost
Reduced print time – using the correct amount of fibre results in a faster print time for example; a striped fibre strategy is considerably less than printing a part flooded with fibre
The different S hooks results
The Onyx only component served as a base line of comparison, so we can see the benefits of fibre when compared to Onyx on its own.
When comparing the striped and solid fibre parts, we can see that the solid part used almost eight times the amount of fibre, at three times the cost.
The striped fibre part had a print time of 4 hours and 15 minutes, compared to 6 hours and 39 minutes for the solid component a saving of nearly two hours of print time.
What do these results tell us?
First, we’ll analyse the differences in deformation between the two fibre parts, using the Onyx Only part as a base comparison.
All the parts, after printing, began at a length of between 128mm and 128.4mm – a mere maximum of 400micron difference across the parts.
At a 5kg weight, the Onyx part elongated 1mm from the starting point – think about the tolerances required for your parts!
At the same weight, the striped fibre part stretched 0.5mm, and the solid fibre part only 0.3mm.
Even now, we can see that the differences between the striped and solid fibre parts are minimal, with only a 0.2mm elongation difference at a 5kg load.
Jumping to 10kg, we can see that the Onyx only part has a 2.8mm elongation from the original dimension.
Compare this with the striped fibre part, where there is a 1.3mm total elongation compared to the original.
Finally, the solid fibre part has a 0.5mm elongation.
While this may indicate that the solid part is better, take a moment to consider your application. Is the lesser elongation at such a load worth three times more in part costs? And eight times more material volume?
What is our conclusion?
Solid fibre, while technically making parts stronger, brings a very marginal gain and does not outweigh the benefits of striping fibre which drastically reduces part cost, material usage and print times.
Small adjustments to the amount of fibre can make all the difference. For example, the solid fibre S hook uses 22% of a full 50cc fibreglass spool, compared to only 3% for the part with fibre striping, whilst only seeing marginal gains to the overall part strength.
The ability to add reinforcing fibres into parts 3D printed on a Markforged composite 3D printer is invaluable.
There are a number of different ways and tools that can be easily applied to help select the correct amount of fibre required in your part, based on the end performance parameters required.
Selecting the right fibre strategy, whether manually through techniques such as fibre striping, or via Markforged Simulation software (see Blog "Validating Parts Prior to 3D Printing) ensures that you are able to deliver functional and strong components and parts, with excellent performance in tough manufacturing environments.
New to Markforged? Speak with one of our Markforged specialists who will be able to run through your applications and test print so you can see how best to apply this technology into your business
Or call us on 0800 689 1011