Conceptually, support-free printing has many benefits, which is why it continues to be an aspiration within the industry. Not only would it mean less material is used and wasted after the fact, but it has other productivity and financial advantages as well. The big question is whether it is physically possible to 3D print entirely support-free?
In additive manufacturing (AM), supports are commonly used in the process of a build to reinforce and maintain the structure of the part being created. This is necessary for various reasons, depending on the size and shape of the part being constructed. Support-free building, on the other hand, refers to developing ways to produce 3D-printed parts entirely independent of any support structures.
When used, the supports are placed strategically to prevent deformation from thermal stresses, encourage heat transfer away from the melted material and protect the forming part from the recoater blade, which may cause disruption to the part’s shape if impacts occur. They can also provide additional rigidity to the part during the build process by, for instance, attaching it to the build plate to keep it steady.
Support-free printing would do away with supports, allowing a part to be constructed entirely free-standing and ready to go as soon as the print is completed.
Supports essentially function as small, raised build platforms under the part being made. These provide additional structure to the build. In some circumstances, without the right support, a part will fail to form fully. This is most common with overhanging sections of a part or when a part needs a hole that goes all the way through; either of these scenarios will only progress so far before they’re unable to anchor themselves during the build process. Using supports allows for parts with a narrow base or gaps to be produced.
As a general rule, supports tend to be required for any aspect of a build that extends under 45° from the build platform—this means any part that elevates at an acute angle may need supports factored into the build.
While the construction of supports during the AM process is beneficial to the creation of more complex and elaborate parts, it also has several drawbacks. These are mainly in relation to print times, materials, and post processing.
Print Times—Each of the supports need to be progressively printed with each layer of the build—in the same way that the part itself is created layer by layer. This results in longer print times that reduce efficiency and use more energy, impacting the cost of builds in more ways than one.
Material Consumption—As supports are constructed in the same way as the rest of the part, superfluous materials must be used to create them. The supports are removed from the final product in post-processing and disposed of as waste material, which affects time and costs.
Post Processing—Most 3D-printed parts go through a post-processing, which can consist of several stages depending on what’s required to finish the part and make it suitable for use. This can include machining and surface treatment to enhance the part’s accuracy and reduce surface roughness, and heat treatment for improved mechanical properties as well as the removal of thermal stresses incurred during the build process. A final cleaning stage is often required to remove any extraneous powder.
Building with bigger and more supports requires a longer and more intensive finishing process. This time-consuming process is not only manually demanding, but it also comes at an additional cost. Specialist labor time and the requisite tools add to the bottom line for product manufacturing.
There are also instances where some supports are inaccessible and therefore cannot be removed. While these may not prevent the part from functioning, they will add weight and potentially impact the overall performance of the part. In the case of precision engineering, the ability to print without those supports could have resounding benefits for the future use of the part.
By shifting to support-free 3D printing, the AM process can be improved economically, environmentally, and by speed. Not needing to construct supports during the build means less of the material in the powder bed will be melted, which has multiple benefits for AM.
There are three key “speed-hack” benefits, including:
Less Production Time—If the lasers in the printer don’t need to continually add layers to the supports as the build progresses, it will cut down on the print time. While for each single layer of the build this will have a small time-saving impact, over the course of a complete build, it adds up to a significant reduction in the time it takes to complete the production of a part. Applied to large-scale manufacturing, this empowers companies to cut production times even more.
Post-Processing Resources—Not having supports in the first place would mean their removal is completely eliminated from the post processing phase, significantly impacting lead times. A large amount of the time spent in post processing is focused on support removal. Because they are attached to the final product, they need to be machined or ground away and the surface treated until it’s matched perfectly with the rest of the part’s surface.
This requires special skills and tools that cost companies time and money. In extreme cases, a one-minute processing step during the build can increase lead time by a full day. A support-free build would do away with the need for such intensive post-process adjustments, making it far quicker and cheaper to complete a part. Without needing to remove the attached supports, the printed part will also have a better, more consistent surface finish immediately.
Consume Less Material—With sustainability and responsible manufacturing in mind, it’s clear that not using supports (or even reducing them in size and number) will mean less material is used. This results in less material waste and reduced energy expenditure, cutting down on both the financial and environmental cost of 3D printing. It also reduces the overall time of both the initial printing process and the post-process procedure to finish the part, allowing for greater efficiency and simplicity.
The reality is that 100% support-free AM currently isn’t possible for every application or geometry. That isn’t to say that it may not be in the future, though. At EOS Additive Minds, we’ve recently made some incredible leaps in getting closer to the end goal of support-free printing.
Probably the most sustained limitation of metal AM is that you cannot print below a certain overhang angle without supports. Without supports, the overhang is at risk of warping due to the residual stresses caused by exposure to the focused energy of the lasers during the print. This often restricts users of metal-AM systems in their choice of applications.
Thanks to the innovative thinking of industry leaders, the critical 45° angle is now being questioned and challenged. Many software and parameter packages have now become available that enable users to print overhangs and bridges at much lower angles without compromising the effectiveness of the 3D-printing process and quality of the metal parts produced.
Consider a recent case involving shrouded impellers, where a support-free build was achieved despite pushing the limits of overhang angles to an impressive 10°. This project also saw the complete elimination of internal supports, which makes post processing much less complicated—awkwardly placed supports inside a part can be some of the most challenging to remove, even if they’re not the largest. Through these reductions in the size and number of supports, the overall cost of production for the impellers was reduced by 35%.
The process development team has taken the findings from bespoke, specialist projects like this and applied them to the standard processes that are available for “plug and play” 3D-printing software. This means that now, even without an expert consultant, you can reduce angle limits to 20° as standard.
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