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How Orientation Affects a 3D Print
The Importance of Part Orientation
1. Part Strength
When the team at Forge Labs receives a CAD file for 3D Printing, they must decide on how the part will be oriented during printing in order to optimize for strength, surface finish and the lowest cost per part. Often, prioritizing one aspect can easily compromise another. With this in mind, our technicians work closely with customers to optimize part orientation according to their needs.
Forge Labs uses a variety of 3D print technologies to produce parts, but they all share a few things in common. All of our print technologies print in discrete layers, and they all require some form of support to hold the part in position during printing. They also all require a post-print process to remove the support material and deal with artifacts from printing. Any additional finishes or modifications happen last. The end result is a strong, clean and finished part.
Each print technology has its own set of constraints which directly impacts the strength, finish and price of a part. In this overview we will focus on these three variables, which are common to all of our print technologies.
Forge Labs specializes in manufacturing end-use functional parts and prototypes. Therefore our first priority with any part we manufacture is to optimize its strength. 3D Print orientation can have a significant effect on how a finished part performs under stress. This is most critical for FDM because of its non-isotropic nature. It requires less force to delaminate layers than it does to tear a single layer, much like how wood splits more easily along its grain. By contrast, Powder Bed Fusion technologies like SLS and Resin technologies such as PolyJet & SLA have significantly more uniform density, but orientation should still be considered in regards to the forces being applied to the part. A good example is a snap fit part that is designed to bend during use. If the force of bending is shared by all of the layers that make up that component, it will resist. If it is isolated to the bond between a few layers, it will fail with much less force.
Orientation & Part Strength by Technology
Powder Bed Fusion | Fused Deposition | Stereolithography | PolyJet |
Not Critical* | Very Critical | Not Critical* | Not Critical* |
*Orientation becomes more important on parts with thin features
2. Material Usage
The orientation of a part has no effect on its own volume, but it does affect the amount of support material used, most prominently with SLA & FDM technologies. Orientation is also important for Powder Bed Fusion & SLA technologies since it directly effects how densely we can build parts. The higher the density, the greater the scale of economy we can achieve as less material is wasted. Material usage is directly related to part cost, and therefore by reducing material use, it minimizes the per-part-cost as well as reduces 3D printing turnaround time.
This is our second biggest priority when manufacturing your part.
As a general rule, we will always minimize the amount of support material required to keep the total volume down. This often goes hand in hand with the z-height of the part, but not always. There are also cases when this priority is overshadowed by another. Often maximizing the Z height helps to improve surface finish, but often leads to a higher print cost and may reduce strength due to layer splitting. In these cases we will prioritize part strength over cost.
Orientation & Material Usage by Technology
Powder Bed Fusion | Fused Deposition | Stereolithography | PolyJet |
Somewhat Critical | Critical | Not Critical | Very Critical |
3. Surface Finish
As with any manufacturing method, parts will inevitably be marked in some way with artifacts from the process. A common example is seam lines in injection molded plastic parts. 3D printing has its own set of artifacts - most notably, the stepping effect that results from rounding between layers. Stepping is most pronounced when the geometry is at a low angle relative to the build platform, which means that the line drawn by the laser or extruder is caught between two slice heights for a longer distance, and gets separated into visible terraced sections. Exaggerated stepping usually requires sanding or filling, which increases post processing time.
This varies depending on technology, but is a general concern for most methods. If there is a preferred surface of the part (an A surface), then it can be oriented to minimize support on that face. This can become complicated by competing constraints, such as holes or areas of complex geometry that are difficult to access being filled with support material.
Optimizing for surface finish is often our last priority when manufacturing parts, since our industrial machines can achieve very tight tolerances, resulting in a high quality surface finish regardless of orientation. Surface finish can also be improved in the post processing stage, so even exaggerated stepping can be removed using our in-house finishing techniques which include sanding, bead-blasting, dying & painting.
Orientation & Surface Finish by Technology
Powder Bed Fusion | Fused Deposition | Stereolithography | PolyJet |
Somewhat Critical | Very Critical | Not Critical | Not Critical |
The Bottom line
As you can see, there is a direct relationship between orientation and the factors that affect both price & strength throughout the manufacturing process. Our experienced technicians and engineers manage this balance artfully on a daily basis.
We highly recommend you take advantage of our design guidelines to better understand how to design parts that make the most of our print technologies while keeping part costs down.
