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how to get the best orientation of a part for 3D Printing

Oct. 10, 2022

With every 3D print, there are several ways you can position a model on your print bed, it may seem like a no-brainer to opt for the orientation that offers the minimum z-height, which will minimize the presence of overhangs so fewer support materials are needed, this results in faster printing times, less material used & stronger parts. But there are a few other technical factors that need to be taken into account when thinking about the orientation of a part for 3D printing, in this article, we'll show the factors and let you know how to choose the best orientation when doing 3D printing.

First of all, let us show why orienting solely for z-height may not always make the most sense in terms of your part requirements, take commonly used SLA(stereolithography´╝ëfor example, think of a rhombic cup, when doing 3D print, what will you do? horizontally or vertically print it layer-by-layer?  Doing it horizontally will take less time but requires more support structures when comparing doing it vertically, right? Because when printing vertically, it's standing tall and requires more drawn layers stacked sequentially one on top of another, which will take more time, on the other hand, printing it horizontally will require more support structures and those would require additional time to remove to achieve a finished part. So, your orientation selection could come down to strength requirements, print time, amount of material used or surface finish requirements for your cup, maybe you plan to do a more complex part, so let us check which factors will affect your choice of the orientation.

1, Orientation Strength of part

one of the main factors that we focused on 3D printing is the strength of the printed part, if 3D printed parts were weak and can't bear heavy loads, it can't as popular as it was today. Your 3D print orientation strength changes depending on how you set things up.

As we know, 3D prints are built up layer by layer, but we have to account for which way the layers are being built. When you have a mostly vertical object- the rhombic cup, you don't want your directional infill to also be going vertical because it means the part won't have much horizontal force and will be easy to break. Let's give a quick look at the illustration that explains the general implications of 3D printing layer buildup and the strength of the parts. When tension forces are perpendicular to the layers, the part is weak, but when tension forces are parallel with the layers, the part is strong. So when you have a mostly vertical object, you don't want your directional infill to also be going vertical because it means the part won't have much horizontal resistance and will be easy to break.  On the other hand, when bending forces are normal to the layer, the part is generally able to accommodate more compression than if bending forces are in line with the layers. It's similar to having a long, thin stick and trying to break it. You wouldn't try to break it vertically by pushing it down on itself because that's where the strength lies. You would rather break it by bending the stick horizontally in the middle.

In summary, two takeaways apply,

1) print in an orientation so that layers align with the axis where tension forces are highest

2) print in an orientation so that layers intersect the axis where compression forces are highest.

2, Orientation to get desired surface quality

Most clients asked for a cosmetic finish for use in a show or display,  in this condition, we'll tend to build the part flat and not at an angle, by positioning the path in a certain way, the less layer lines you have, the less wrinkle you have on your model. This means we can use orientation to make specific surfaces smoother, you may not have noted that certain surfaces are better quality than others when printing, the smoothest surface is usually the one that is directly on the print bed, especially the glass bed,  the top surface also usually has a pretty smooth print surface due to the tip of the extrusion being smoothed over. so when surface quality is a priority,  you can place the side you want to be smooth face down only if it's possible and makes sense, and you need to avoid supports structures because they need to be removed and blasted would eliminate any glossy effect.

3, Orientation to avoid differential shrink

We know differential shrink happens in plastic injection moulding and some measures should be taken to minimise this phenomenon,  it also happens in 3D printing, in general, the more unequal distribution of material there is in a part, the more prone it is to fall victim as differential shrink, such as the letter "H", when the crossbar section appears layer-by-layer in the middle from 3D printing, it tends to pull the supporting lets inward, causing the part to bow near the bottom.

There are a couple of ways to prevent differential shrink, often, we build 3D printing parts on an angle to reduce the surface area and then the overall stress encountered on each layer, in addition, we can build parts lying down so that each layer formed is the same surface area and there are no large cross-sectional swings, but building parts on an angle may result in parts with non-pretty surface finish.

4, Other factors that help part of Orientation

Minimizing layer lines for Orientation, the reason to look at layer lines when discussing part orientation is able to create a smooth-looking part.

Also, when it comes to large 3D-printed parts, splitting them is a necessary step, rather than just blindly splitting parts up, we can plan out and recognize the best way to split them by taking part orientation into account.

Now that we have identified what to consider, let's look through and put this information together to give us a summary, many a time, there will be one or more orientations which are appropriate, however, there will be cases where the most accurate orientation may not fit with your 3D printer's defined build volume or catch your needs.

As a rule of thumb, our team may help to choose the right orientation to provide you with the best quality part, we may compromise certain aspects of the print, or perhaps we redesign or edit the file to better suit the print process, By understanding each constraint and using these tips and tricks, we can prioritize, through taking advantage of orientation, the most critical aspect of our print.  

so if you have any questions on the orientation of 3D print parts, kindly contact us for details.