3D-printed objects are only getting better as technology advances, and sometimes, the prints can be so good it’s hard to tell that they are 3D printed. However, if you look closely, you can usually find some clues to tell you that something is a product of 3D printing.
The easiest way to tell if something is 3D printed is by examining the object for signs of visible layers. You can also distinguish 3D printed parts based on the materials used, the geometry of the objects, the texture, and the weight.
Let’s dive into the intricate details of 3D printed objects and look at the easiest ways to tell if it is 3D printed. I’ll guide you through all the clues and hone in on each sign so you can always recognize a 3D-printed object when you see one.
1. 3D-Printed Objects Have Visible Layers
3D printing technology uses a layer-by-layer approach to create objects from thin filament strings or short photosensitive resin layers. This process is why 3D technology is defined as an additive process – adding one layer to another.
Because of this layer-by-layer approach, it is possible to distinguish a 3D-printed part from a non-3D-printed part.
While 3D printing enthusiasts and pros may attempt to hide and sand away the ribbed “steps” of these layers, they will always be easy to spot on the object.
They appear as seams between small layers of plastic or resin. Unsanded, these layers reveal that 3D printers use square-shaped layers to create a stair-step effect to print curved objects.
On a straight box, you may see the ridges between each layer, where the previous filament layer fused to the next.
In addition, these layers are most apparent when well-lit, as each ribbed divot can catch and reflect light.
Once these layers reflect light, the individual layer lines become visible. Although manufacturers continue to find ways to hide these lines, most 3D-printed parts will have this identifying characteristic.
These layer lines are simply a part of the process, especially in large-scale manufacturing. They describe these lines as resembling the grain in timber and clarify that these layers can look more pronounced and messy at times.
Therefore, an excellent first step to determine if something is 3D-printed is to look for visible layer lines.
2. Materials Used
It is also possible to distinguish a 3D-printed object from an object made from traditional material based on the material used. The most common material in 3D printing is polylactic acid (PLA), but ABS is another common one.
The preference for PLA primarily lies in its being the easiest filament to print. PLA is a form of plastic made using vegetable starches and other chemicals, and since it uses byproducts of food production, it’s also pretty cheap.
ABS plastic is the second most commonly used in 3D printing, but it’s also popular for injection molding and other manufacturing processes. You’ll find it in Legos, toys, food preparation utensils, and hard hats.
Some of the significant strengths of this material include tolerance to high temperatures and a high degree of impact resistance. However, when 3D printed, this shiny material reflects light very well, making layer lines the critical characteristic to look out for when identifying 3D printed ABS.
Other commonly used materials include TPU plastic, lauded for its flexibility, PETG plastic, and PVA. While it is possible to use metal alloys when designing functional mechanical parts using selective laser melting, the most commonly used materials used for 3D printing are plastic.
All these thermoplastic polymers have one thing in common – they are generally cheaper and more readily available than metal alloys and other materials.
Accordingly, it is possible to distinguish 3D-printed objects from non-3D-printed objects based on the materials used.
3. The Object’s Weight
One of the significant strengths of 3D-printed parts and objects is that they are lighter than non-3D-printed things. Much research and development in 3D printing have focused on making parts lighter yet stronger.
There are several reasons why 3D-printed parts and objects will be relatively light. The first is due to the materials used.
As stated above, most 3D-Printed parts consist of a thermoplastic polymer. Plastic is much lighter than other materials, such as metal and metallic alloys.
Secondly, 3D-printed objects contain infill to reduce the material used without undermining strength. These hollow geometric patterns make it easy to print an object without filling the inside. As the gurus at Xometry explain, the goal of using infill is to optimize weight while reducing printing time.
Objects that utilize infill in the printing process tend to be typically hollow and thus lighter.
Third, 3D-printed objects are not very dense. When you compare a 3D object to an injection-molded object, you can see that the 3D-printed one’s walls include more air, are thinner, and may even be hollow.
On the other hand, the injection-molded object will be solid and significantly denser – AKA heavier – than the 3D-printed one.
Additionally, because these objects are predominantly plastic, they tend to be relatively brittle and lighter when compared to non-3D-printed parts or things.
For instance, a 3D-printed gun, while being functional, will be much lighter and more brittle when compared to a traditional firearm.
4. Shape and Geometry
A 3D printer moves across the X-Y axis, depositing one layer over another until the printing process is complete. Therefore, this motion path significantly impacts the shape and geometry of objects made using a 3D Printer.
As explained on the R&D website, because 3D printers use a layer-by-layer building process, the end product has a stair effect along the edges. Likewise, 3D printers do not create genuine circles. They use a pinpointing feature to connect many short, thin lines to create any shape.
Therefore, while a 3D Printer can create an object from a digital file with near-perfect precision, it is limited in the geometry of these objects.
Most traditional 3D printers cannot create specific shapes, particularly arches. Such forms require additional specialized tools and support to execute accurately.
However, it is crucial to appreciate that, as this technology grows, modern 3D printers can support shapes such as arches. This fact notwithstanding, it is possible to tell whether something is 3D printed by examining the edges.
5. Uneven Surface Texture
The texture and surface quality of 3D objects depends on the technology used, the printer’s orientation, and the technology. However, most objects created using a 3D printer do not have a homogeneous surface, even for liquid-based systems that rely on stereolithography.
Accordingly, these objects require additional finishing work to eliminate these surface scars. These surface scars are more prevalent in things made using powder-based systems. Consequently, most end products tend to have a rough surface.
Other factors, such as over-extrusion and under-extrusion, also affect the texture of 3D-printed parts and objects.
It is, therefore, possible to determine whether an object is 3D-printed by examining its texture and surface roughness, assuming that no post-processing work has been done on the model to smoothen the surface.