Fused Deposition Modeling and Digital Light Synthesis are common, yet very different methods of additive manufacturing. Fused deposition modeling, or FDM, uses a strand of material, building the part layer-by-layer, whereas digital light synthesis (DLS) employs a single or two-part resin that cures parts into shape using light or thermal heat. With both of these methods presenting viable options for 3D printing, we’ll discuss the manufacturing properties of each, which method is best suited for a given task, and when each method presents cost-effectiveness.

In a recent test at Wilson Tool International, our Carbon3D DLS machine was able to produce 32 parts in the same time it took our FDM machine to produce one.

Structural Rigidity
DLS parts are isotropic in nature, meaning the parts deliver omni-directional strength. The FDM process produces a part that’s anisotropic, meaning the part is strong in the X and Y direction while having some vulnerabilities in the Z direction.

DLS vs FDM Close-up

Part Quality
Not only is it faster, the DLS process also produces a higher quality part. Layer/build lines are an inherit nuisance of 3D printing, especially evident in the FDM method. The DLS process produces a cleaner part with more detail, while still showing subtle build lines.

FDM, although slow and visually noisy, is easily one of least expensive ways to additively manufacture a product. The DLS process will cost more than FDM process but is less expensive than a molding process. DLS is very cost-competitive against technologies such as SLS (Selective laser sintering).

When Should One Method Be Used Over the Other?
The DLS method produces clean, tolerance-focused parts in short order – but don’t count FDM out just yet. FDM parts are inexpensive and are good for use in low-run production and prototyping, where tolerances and finishes are fairly open. It’s one of the slowest methods, but it’s materially versatile and it’ll certainly keep your costs to a minimum.

Contact Wilson Tool International for expert advice on everything from prototyping to first good part – call a tooling technician at 833-345-0087 or email


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