How to Choose the Right 3D Printing Process: An Analysis of Pros and Cons

The initial contact might feel a bit confusing, but you must know that adding bricks layer by layer to build a building is quite similar to the principle behind 3D printing.

The origin of 3D printing can be traced back to the 1980s. In 1983, American engineer Charles Hull invented “stereolithography” (SLA), which is considered the first 3D printing technology. He used ultraviolet light to cure liquid photopolymer resin, solidifying it layer by layer to create a three-dimensional object. This is why he’s often referred to as the “father of 3D printing.”

3D printing, also known as additive manufacturing, is the opposite of subtractive manufacturing techniques like CNC machining. Its working principle involves breaking down a complex three-dimensional structure into countless two-dimensional planes, building it up layer by layer to turn a virtual model into a physical object. This overcomes the limitations of traditional subtractive methods (such as cutting) in terms of geometric shapes.

Stereolithography technology was initially used for rapid prototyping, and its key advantage lies in its ability to efficiently create physical prototypes of new parts and products.

SLA is a 3D printing technology based on photopolymer resin curing. The principle involves using a UV laser to scan and cure the resin point by point in a liquid resin vat, forming a thin layer. After each layer is cured, the build platform lowers by one layer thickness, allowing fresh resin to cover the cured layer. The process repeats, curing the resin layer by layer to ultimately form a three-dimensional part. After the formation is complete, excess resin must be cleaned off, and secondary UV curing is performed to enhance the mechanical properties and stability of the part.

High precision, with errors controllable within ±0.1mm. Smooth and delicate surface finish, with high detail reproduction. A wide variety of photopolymer resins available to meet different needs,Relatively fast printing speed (especially for small-sized parts) and low cost.

Long-term stability is insufficient; parts exposed to sunlight or UV light for extended periods may experience aging, yellowing, and performance degradation. Low strength, limiting its suitability for functional testing.

Infrared lasers or CO2 lasers are used to scan and sinter the powder bed layer by layer: First, the metal powder is uniformly heated to a temperature slightly below its melting point using a preheating system. Then, the laser beam scans according to the cross-sectional data of the 3D CAD model, causing the powder particles to fuse and form under the thermal influence. Un-sintered powder particles naturally form a support structure, preventing collapse in areas with overhangs. After sintering one layer, the build platform moves down 0.1-0.3mm along the Z-axis, and the powder spreading device evenly lays down a new layer of powder. This process is repeated until the entire part is formed.

Excellent mechanical properties.

Products are sturdy and durable.

Excellent corrosion resistance.

Printed parts may have a noticeable grainy texture on the surface.

Dimensional accuracy is lower than SLA.

Large parts may experience deformation issues.

The filament material (wire) is fed into the nozzle through a feeding mechanism. An integrated heating device inside the nozzle melts the filament into a semi-liquid state. The nozzle moves along the sliced path on the print bed, extruding the molten material and depositing it in the specified locations. The material quickly cools and solidifies to form one layer of structure. After each layer is completed, the platform lowers (or the nozzle rises) by the thickness of one layer, and the extrusion and curing process is repeated until the part is fully formed.

Low equipment and material costs.
A wide variety of materials available, with high safety.
Offers a certain level of strength.

Lower precision, with noticeable layer lines and rough surface finish.
Limited suitability for functional testing.
Low strength in the Z-axis direction.

Rapid prototyping to verify structure and assembly relationships.Suitable for functional parts that require chemical resistance or high-temperature resistance.

High part density, approaching or even equivalent to forged material performance. Capable of producing parts with complex geometries.

Low efficiency, not suitable for mass production.

High cost.

Rough surface finish, usually requiring post-processing or surface treatment.

Suitable for parts with complex structural shapes.

Suitable for high-strength, high-hardness, wear-resistant, and high-temperature functional metal parts.

One-piece formation reduces the need for metal components in assemblies.

The principle of MJF (Multi Jet Fusion) technology involves first laying a layer of polymer powder on the build platform. Then, a selective application of fusing agent and detailing agent is sprayed. Infrared light is used to rapidly melt and solidify the areas sprayed with the fusing agent, while the detailing agent controls the precision of the surrounding areas. After each layer is completed, the platform lowers by one layer thickness, and the process is repeated layer by layer until the complete 3D part is formed.

Suitable for manufacturing strong, durable, and heat-resistant functional parts.

Uniform mechanical properties across parts.

Cost-effective.

Very large parts are difficult to print directly.

Potential risk of deformation.

Parts requiring high strength and toughness.

The process with the finest detail is not always the one that delivers the fit, and the cheapest process is rarely the one that holds an assembly. Published design bands put SLA around ±0.05–0.1 mm, SLS, MJF and metal processes around ±0.2–0.3 mm, and FDM at ±0.2–0.5 mm, which means the process choice decides whether a bore needs reaming before anything else is discussed.

The bands are the ones the shop publishes in 3D printing tolerances by process. Treat them as design starting points rather than guarantees: shrinkage and warpage are the silent variables, they differ between machines and even between positions in the same build, and a part that must fit another part is usually safer printed slightly undersize and finished.

Assume a 6.00 mm bore that has to take a 6.00 mm steel dowel with a sliding fit, and that the print tolerance behaves like the published band. An FDM part at ±0.5 mm can land anywhere between 5.50 mm and 6.50 mm, so the worst case is an interference fit on one part and a 0.5 mm rattle on the next. An SLA part at ±0.1 mm lands between 5.90 mm and 6.10 mm, which is closer but still not a controlled fit.

The practical route is to stop treating the printed bore as the finished feature. Print the bore undersize — 5.80 mm is a reasonable starting point for a process with a ±0.2–0.3 mm band — then ream or bore it to the drawing after printing. That converts an uncontrolled printed dimension into a machined one, at the cost of one extra operation and a note on the drawing. The same logic applies to any mating feature: if it needs a class of fit, machine it; if it only needs to be close, print it.

For choosing between the three common plastics processes, the shop’s own selection table puts visual and detail work on SLA, functional thermoplastic parts on FDM or SLS, complex geometry with internal cavities on SLS, and the cheapest quick iteration on FDM, which matches the tolerance picture above: FDM vs SLA vs SLS.

Three consequences are worth planning for before the file is released. A printed thread is a thread in name only, because the layer staircase changes the effective pitch diameter; print a pilot hole and tap it, or use a heat-set insert. A part that must be watertight needs a material and a wall thickness that closes the layer boundaries, which is not the same as a part that merely looks solid. And a print that will be handled daily needs the anisotropy understood: properties along the layers and across them are not the same, so the load path belongs on the drawing, not in the printer operator’s judgement.

When 3D printing parts, DFM (Design for Manufacturability) guidelines should be followed to avoid the following issues: Following DFM principles is key to avoiding problems with 3D printed parts. The following points should be considered during the design process:

Deformation of 3D printed parts can be caused by various factors, such as material properties, printing environment, and part design. Effective methods to prevent warping include optimizing the print orientation, reducing overhangs, adding support structures, increasing wall thickness, and incorporating reinforcement ribs in large surface areas to prevent sagging.

In 3D printing, large overhang structures can cause issues because they require support structures underneath. This not only increases print time and material consumption but can also lead to a decrease in surface quality at the bottom of the overhang.

Whether you’re creating prototypes or producing end-use parts, additive manufacturing (3D printing) offers significant advantages. We provide a wide range of materials and processes, enabling ultimate geometric flexibility and rapid iteration, so you can receive high-quality parts in just a few days. For any questions about quotes or design, our applications engineers are ready to provide expert guidance and support to ensure your project runs smoothly. We look forward to collaborating with you on your next project!