Sustainability (and profit) in FDM 3D Printing

I understand that you run a business and sustainability might be the last thing you’re worried about. Fear not, for this guide is designed to help you improve the sustainability of your 3D printing in ways which will also improve your profits.  

My definition of sustainability is about whether or not we can do something forever, including all of the externalities we create such as waste, pollution or even stress.

Sometimes this involves minimization of waste in all its forms, including material, energy, labour and time. Sometimes improving product quality and longevity will lead to products which are never thrown away and serve their purpose for decades. For the products that don’t make it that far, we can ensure its end of life is well managed.

Many of the principles in this guide also serve to reduce operating costs and improve product quality. By working on these areas, you can increase the profitability of your FDM 3D printing and simultaneously decrease its impact on the environment.

Part 1: Avoiding Mistakes

Measure thrice, print once (design, slicing and printing)

Mistakes in printing inevitably lead to wastage. When a print fails, we waste material, energy and time without any financial benefit at all. In 3D printing, the cost of mistakes includes wasted plastic, wasted machine time/opportunity cost and labour used for tasks like correcting design mistakes and resetting machines. In some cases, these can be errors in measurement and design. At other times, it can be mistakes in machine setup, material choice and operation.

When designing parts, triple checking measurements, angles and shapes can minimise wasted time and money in production. The resources spent ensuring print success will usually be less than what we can save from failed prints.

In the slicing stage, ensure that the scale of the part is correct by checking the dimensions shown in the program. Also ensure that the layer height and line width is small enough to capture the details of your part. If it isn’t, you may need to switch nozzles before printing. Make sure that the part is sitting flat on your build plate, not floating or on an angle. Always make sure to preview the Gcode and look at the machine paths – ensure it makes sense and that supports are I place where necessary.

Finally, SAVE YOUR PROJECT FILE! This file contains the model and the settings used to print it. This is critical for future improvements and for diagnosing print defects.

Before printing, ensure that the loaded material matches your print file (I know it’s obvious, but I’ve seen big issues arise from this). Ensure that the build plate is clear and clean, then apply adhesives if your material requires it. You can check with your printer or filaments manufacturer to see how they suggest that you prepare your print in a given material.

Always observe the start of a print and ensure it matches the Gcode preview you saw earlier.

During printing, ensure that nothing will disrupt the machine including its power supply, cold winds and the bench it’s on.

Material storage also applies here. Ensure your printing material is new or dry to ensure print reliability and quality. We will talk more about material management in a future post.

Sustainable Part Design

In the design phase, there are a few things you can do to make a part more sustainable at no extra cost.

Reduce Material

In a similar way to making a part lightweight, cutting away unnecessary material from the part will often reduce the total plastic needed to print it. Tools like simulations and generative modelling can help you to achieve this.

Add end-of-life markings

Most plastic products you see will have recycling or disposal markings marked on them somewhere. This allows users to dispose of them properly in general waste, recycling or even compost.

You can easily emboss or deboss these markings onto your parts. After identifying the material you will print with, add the appropriate marking to a face on the part. In CAD, you can extrude or cut into the part to add the marking.

Note: I’ve had a lot of trouble finding files for the Australian recycling symbols to be used on plastic products. There is plenty of information available for the packaging sector, but I can’t seem to find symbols for recyclable products.

Durability and Wear

By improving the durability and quality of a part we can extend its useful lifetime, disposal and replacement. During design, consider carefully which sections of a part will wear out first and see if they can be reinforced. By extending the lifetime of the part we can reduce costs, minimize downtime and reduce the number of broken parts disposed.

In high stress applications, also consider whether 3D printing is the right choice. Long-term fatigue is a known weakness of 3D printed parts, so metal could be a better option. Stresses which will affect your printed parts long term can be heat, ultraviolet light, hydrolysis and physical force.

Material Choices

Where possible, consider using recyclable or biodegradable materials. This allows the part to avoid landfill and be useful once again. There is much debate about what is truly recyclable and biodegradable and it varies between plastics. Check with your material suppliers and your local waste authority to see what is appropriate.

These factors obviously need to be balanced with the performance of the part.

Note: PLA is typically regarded as a biodegradable filament, however many people use different definitions of ‘biodegradable’. The most important definition is the one of your local laws and regulations . This also applies to ‘recyclable’ materials.

Multi Extrusion

Multi-extrusion machines are able to combine materials. When using a material which cant be recycled or biodegraded, such as PC-CF, you can print the support structures with a biodegradable materials such as PVA or PLA. Please note that each manufacturers filament is different as well as disposal guidelines locally and their definition of these terms.

Avoid mixing materials

For sustainability purposes, having a part made from a single plastic greatly improves its end-of-life. If plastics are mixed or combined with metals for example, they can no longer be recycled or composted. There may be exceptions to this, such as where two materials are both biodegradable/recyclable in the same process.

Where possible, replace additional components with features in your CAD design. For example, magnets can be replaced with snap-fits when two parts need to join together. Metal threaded inserts can be replaced with 3D-printed threads if they still meet your strength requirements. By doing this, you can cut costs on parts, assembly and improve the end-of-life for your products. If an entire part is made from a singular material, it is far easier to biodegrade or recycle it.

Material Minimisation in Slicing

As long as it meets your strength requirements, parts can be printed with very minimal material. If your part does not require strength, you can reduce the wall thickness, top & bottom layers, infill and support density. Lightning infill can be used to minimise internal material and tree/organic supports can be used to minimize support material.

The most important printing parameters in part strength are line width, perimeter width and top/bottom layers. Line width can be increased without changing your nozzle, although it shouldn’t exceed 50%. Infill has diminishing returns on strength, which makes is the perfect place to minimize material usage.

Most printers will have some form of priming or purging of the nozzle during the print, which produces small pieces of wasted plastic. These settings can be adjusted to reduce the amount of purging or priming performed by the machine. I like to turn of brims and skirts where possible, because they often are simply wasted plastic. A “prime blob” setting usually uses the least material for the priming process which is preferable to a skirt.

Multi-material printing often involves lots of purging of the nozzle. Single nozzle machines with multi material capabilities, like the Bambu’s, are notorious for their waste during multi material prints. This is because a single nozzle machine needs to be cleaned out or “purged” to minimize material contamination. Machines with independent nozzles generally waste less plastic, because they are primed rather than purged – the machine just needs to equalize the pressure in the nozzle.

To see how much your material your print would use, slice it and see how many grams are shown by the program. Make sure that you have enough of the required plastic on your spool. If not, you can reduce infill, then top/bottom layers and then perimeters

Note: My gutfeel is that reducing top & bottom layers is preferable to perimeters, because they have plenty of surface area to bond while perimeter have little. This is not something I’ve tested, so take it with a grain of salt.  

Tip: To help simplify your designs, you can increase your line width to an easier number like 0.5mm for a 0.4 nozzle or 1mm for a 0.8 mm nozzle. In the design phase, this means you don’t have to use a multiple of your line width for small features.

Supply and Machine Considerations

Spool Maximization

The leftover material on a spool of filament is based on a few factors. A Bowden style printer will have a larger piece of waste material than direct drive. This can be considered as a percentage of your total spool size.

To reduce the line loss in FDM printing, there are 3 things you can do. Firstly, using a direct drive machine will result in less waste material when a spool is finished. Secondly, using a larger spool, such as 3Kg, will reduce the percentage of your material which will go to waste. Finally, planning your prints by weight can allow you to consume a whole spool. If you are printing a 501 gram part with a 1Kg roll of filament, try to reduce the part weight so that you can get 2 per spool rather than 1.

Maintenance

Proper maintenance of your machine will lead to better prints and reliability. Sustainability in printing is also influenced by your machine: it’s lifetime and the need for spare parts.

Regularly maintaining your machine can reduce the need for replacing parts and extend the lifetime of your machine before its end of life. For example, lubricating linear rails and rods will reduce he strain on your motors, minimizing the need for their replacement, reducing noise and improving print performance.

To find out how to maintain your machine, visit your manufacturer’s website. In the future I will write about maintenance in general, but the steps will be different for each machine.

Power Consumption

The power consumption of 3D printers comes mostly from heated beds and chambers. Where possible, these temperatures can be reduced so long as your parts still meet requirements. If indoors, this can have the secondary effect of reducing cooling costs in the building as the heat escaping from the machine will need to be counteracted by air-conditioning.

Suppliers

The location of your suppliers can influence how costly it is to purchase from them. Having an efficient supply chain will be cheaper and better for the environment.

Where possible, source products locally to avoid costly overseas freight. Unfortunately in Australia, local options are very limited for printers and filament. Forecasting your filament and spare part requirements can help make shipping more efficient by making larger purchases less often.

Waste Management

If you intend to recycle or send waste for industrial composting, it is imperative that the waste is sorted. It is best to have separate bins for each type of waste so that they can be recycled or composted efficiently. When mixed, recycling becomes impossible as one material will not be processed properly. Fortunately, thanks to 3D printing, you can easily make a waste management solution yourself. Here is what we use to manage our waste.

Conclusion

Sustainability is a wide ranging topic and there are many ways to achieve it. I hope that this post can help you to improve the sustainability of your printing and perhaps cut some costs too.

Thanks for reading,

Simon