By Philip Wood, Marketing | AdvancedTek
FDM, SLA, and SLS are the three most widely used polymer 3D printing technologies in industrial and manufacturing environments. Each works differently, produces different results, and is better suited to different applications. This guide breaks down how each technology works, what it is best used for, and where its limitations are so you can make a confident decision about which fits your application.
What Is FDM 3D Printing?
Fused Deposition Modeling (FDM) is the most widely adopted 3D printing technology in manufacturing. FDM systems extrude thermoplastic filament through a heated nozzle, depositing material layer by layer to build a part from the bottom up. Industrial FDM systems use a dual-extrusion setup: one nozzle for the build material and one for a breakaway or soluble support material that is removed after printing.
Best Uses for FDM
- Manufacturing jigs, fixtures, and assembly aids
- Functional prototypes in engineering thermoplastics
- End-of-arm tooling and robotic end effectors
- Low-volume production parts in ABS, Nylon, Polycarbonate, or ULTEM
- Large-format parts requiring build volumes up to 1,000 x 610 x 610 mm (Stratasys F770)
FDM Limitations
- Layer lines are visible and affect surface finish without post-processing
- Anisotropic strength -- parts are stronger in X/Y than in Z
- Not ideal for small, highly detailed parts or thin walls
- Soluble support removal adds time for complex geometries
What Is SLA 3D Printing?
Stereolithography (SLA) uses a UV laser or light source to cure liquid photopolymer resin into solid geometry, layer by layer. SLA produces parts with high surface accuracy and fine feature resolution, making it well suited for visual prototypes, master patterns, and applications where dimensional accuracy and smooth surface finish matter.
Best Uses for SLA
- High-accuracy visual and functional prototypes
- Dental and medical models requiring fine detail
- Casting patterns and master patterns for molding
- Clear and translucent parts
- Engineering resins for temperature-resistant or impact-resistant applications
SLA Limitations
- Resins are generally more expensive per kilogram than FDM thermoplastics
- Photopolymer resins are typically more brittle than engineering thermoplastics used in FDM or nylon used in SLS
- Supports must be removed and surfaces post-cured after every print
- Material options are narrower than FDM
What Is SLS 3D Printing?
Selective Laser Sintering (SLS) uses a high-powered laser to fuse nylon or other polymer powder into solid parts. SLS does not require support structures because the unsintered powder surrounding the part provides support during the build. This allows SLS to produce complex geometries, interlocking assemblies, and organic shapes that are difficult or impossible with FDM or SLA.
Best Uses for SLS
- Complex, organic, or lattice geometries with no support constraints
- Functional nylon parts with isotropic mechanical properties
- Low-volume production runs of end-use parts
- Snap-fit assemblies and living hinges
- Jigs and fixtures requiring complex conformal geometry
SLS Limitations
- Surface finish is grainy and requires post-processing for smooth or colored finishes
- Higher equipment cost than entry-level FDM or SLA
- Material options are primarily nylon-based (PA 12, PA 12 GF, Nylon 11)
- Powder handling requires process controls and safety measures
FDM vs. SLA vs. SLS: Side-by-Side Comparison
| Category | FDM | SLA | SLS |
|---|---|---|---|
| How it works | Extrudes thermoplastic filament | Cures liquid resin with UV light | Sinters polymer powder with a laser |
| Surface finish | Visible layer lines | Smooth, high accuracy | Grainy, matte |
| Mechanical properties | Anisotropic (weaker in Z) | Isotropic but often brittle | Isotropic, strong in all directions |
| Support structures | Required (breakaway or soluble) | Required (resin) | Not required |
| Common materials | ABS, ASA, Nylon, PC, ULTEM, PEKK | Standard, tough, engineering, dental resins | PA 12, PA 12 GF, Nylon 11 |
| Best for | Tooling, functional prototypes, production | Accurate models, casting patterns, medical | Complex geometry, production nylon parts |
| Example systems | Stratasys F123 Series, Fortus 450mc, F770, F900, F3300 | Formlabs Form 4, Form 4L, Stratasys Neo | Formlabs Fuse 1+ 30W, Formlabs Fuse X1 |
Which Technology Is Right for Your Application?
There is no single best 3D printing technology -- the right choice depends on what you need to produce, the mechanical properties required, and your production environment. Here is a general decision framework:
- Choose FDM if you need functional tooling, engineering-grade thermoplastics, large build volumes, or low cost per part for production use.
- Choose SLA if you need tight tolerances, smooth surface finish, clear or translucent parts, or detailed visual and functional prototypes.
- Choose SLS if you need complex geometry without support constraints, isotropic nylon parts, or are looking to bring service bureau SLS work in-house.
Many facilities benefit from more than one technology. FDM and SLS complement each other well in manufacturing environments where tooling and functional end-use parts are both in scope.
Frequently Asked Questions
What is the difference between FDM, SLA, and SLS 3D printing?
FDM (Fused Deposition Modeling) builds parts by extruding thermoplastic filament layer by layer. SLA (Stereolithography) uses a UV laser or light source to cure liquid resin into solid geometry. SLS (Selective Laser Sintering) uses a laser to fuse nylon or other polymer powder into solid parts without requiring support structures. Each technology produces different surface finishes, mechanical properties, and material options, making the right choice highly dependent on the application.
Which 3D printing technology is best for manufacturing tooling and fixtures?
FDM is the most commonly used technology for manufacturing tooling, including jigs, fixtures, assembly aids, and end-of-arm tooling. Industrial FDM systems like the Stratasys F123 Series print in engineering-grade thermoplastics such as ABS, ASA, PC, and Nylon, which provide the rigidity and temperature resistance most tooling applications require. SLS-printed nylon parts are also a strong option for tooling that requires complex geometry or snap-fit features. SLA is less common for tooling due to resin brittleness, but engineering and rigid resins can work for low-stress fixtures and inspection aids.
Can SLS 3D printed parts replace machined metal fixtures?
In many assembly and inspection fixture applications, yes. SLS-printed nylon fixtures offer sufficient mechanical strength for assembly aids, welding fixtures, and inspection fixtures. Where SLS has an advantage over machining is in complex geometry -- SLS can produce conformal fixtures and ergonomic shapes that would be expensive or time-consuming to machine. For high-stress fixtures that require metal-level strength, machined tooling or metal AM via EOS DMLS remains the appropriate choice.
Talk to AdvancedTek About Your Application
AdvancedTek's sales representatives have worked with manufacturers, medical device companies, and engineering teams across the Midwest for more than 30 years. Whether you are evaluating your first industrial 3D printer or expanding an existing additive manufacturing operation, we can help you run the numbers, print test parts in your target materials, and make a decision that fits your application and your budget.
Request a consultation or TekCenter demo | Call us: 800-482-9005
AdvancedTek is a Midwest additive manufacturing partner serving organizations across manufacturing, medical, education, and engineering in Minnesota, Wisconsin, Iowa, Illinois, Kansas, Missouri, Nebraska, North Dakota, and South Dakota. As an authorized reseller for Stratasys, Formlabs, and EOS, AdvancedTek provides the equipment, materials, software, and application expertise companies need to adopt, scale, and optimize additive manufacturing in-house.