FFF, resin, powder and metal: 3D printing processes compared

The same polymer can behave very differently depending on how it is printed. A nylon part from a powder-bed machine is not the same as a nylon part from a filament printer. This guide explains the main processes, what each is good at, and which materials in the hub belong to each.

The short version

1. FFF 2250.9–2,000
2. Pellet extrusion 310.7–642
3. SLA 471–230
4. LCD/MSLA 1011–391
5. PolyJet 1510–220
6. SLS 174–310
7. MJF 104.7–440

Bar = lowest to highest, dot = median. 446 materials, live from our database. Log scale.

FFF filament

Fused filament fabrication (FFF, also called FDM) pushes a plastic filament through a hot nozzle and lays it down line by line, layer by layer. It is the most common and affordable way to print.

Strengths: the widest material choice, from PLA to PEEK and fibre-filled grades. Low cost per part. Easy to scale up part size. You can tune infill and wall count to trade weight for strength.

Limits: layers bond less well than the plastic itself, so parts are weaker in the build direction (Z). Overhangs need supports. Fine features and smooth curved surfaces are hard. Read more in print orientation.

Cost drivers: machine time (set by part volume, layer height and speed), material price and post-processing such as support removal.

FFF materials in the hub: 262.

See all FFF materials 262 materials

Pellet extrusion

Pellet printers work like FFF but feed plastic granules, the same kind used in injection moulding, through a screw extruder. They usually run large nozzles on large gantries or robot arms.

Strengths: very large parts, fast deposition and lower material cost per kilogram.

Limits: coarse surface and lower detail. Parts are often machined afterwards. Moisture control and thermal management matter even more than with filament.

Pellet materials in the hub: 33.

See all pellet materials 33 materials

Resin: SLA, DLP and LCD/MSLA

Vat photopolymerisation printers cure liquid resin with UV light, one thin layer at a time. The three main types differ only in how they deliver the light.

SLA

Stereolithography traces each layer with a laser spot. It gives very fine, consistent detail across the whole build area.

DLP

Digital light processing projects a whole layer at once from a projector. It is fast, and resolution is set by the projector’s pixel size.

LCD/MSLA

Masked SLA shines a UV light source through an LCD screen that acts as a stencil. It cures whole layers at once and is the most affordable resin technology.

Strengths: smooth surfaces, sharp detail and good dimensional accuracy. Parts are nearly as strong between layers as within them.

Limits: parts need washing and post-curing, and the final properties depend heavily on that step. Most resins are more brittle and more heat-sensitive than thermoplastics, and some degrade under sunlight. Build volumes are usually modest. Uncured resin is an irritant, so wear gloves.

Cost drivers: resin price, part height (which sets print time), supports and post-processing labour.

Resins listed for laser SLA: 53. For LCD/MSLA: 113. Many resins are sold for more than one of these technologies, so check compatibility with your printer.

Tensile strength across all resins: 1.1–91 MPa (median 44 MPa, 203 materials).

See all resins 223 materials

PolyJet

PolyJet works like an inkjet printer. Print heads jet tiny droplets of photopolymer that are cured instantly by UV lamps. Several materials and colours can be jetted in the same part, and a gel-like support is washed away afterwards.

Strengths: excellent surface finish, full colour, and rigid and soft materials combined in one part. Ideal for realistic prototypes and over-moulding studies.

Limits: parts are generally weaker and less heat-resistant than other processes, and properties can change with light exposure and age. Material and machine costs are high.

PolyJet materials in the hub: 15.

See PolyJet materials 15 materials

Powder bed: SLS and MJF

Both processes spread a thin layer of polymer powder and fuse a cross-section into it, then repeat. The loose powder supports the part, so no support structures are needed.

SLS

Selective laser sintering uses a laser to melt the powder where the part should be.

MJF

Multi Jet Fusion jets a fusing agent onto the powder and passes an infrared heat source over the bed. Only the treated areas fuse. Parts come out grey and are often dyed.

Strengths: complex shapes, internal channels and moving assemblies printed in one go. Properties are fairly even in all directions. Many parts can be nested in one build, which makes batches economical.

Limits: a slightly grainy surface, and small holes can trap powder. Builds need long cooling times. Material choice is narrower, mostly nylons, TPU and PP.

Cost drivers: how densely the build is packed, part volume, powder refresh rate and finishing such as bead blasting or dyeing.

SLS materials in the hub: 17. MJF materials: 10. Elongation at break across all powders: 4–440 % (median 26 %, 27 materials).

See all powder materials 27 materials

Bound-metal FFF

Bound-metal filaments contain a high load of metal powder in a polymer binder. You print on an FFF-style machine, then remove most of the binder chemically or thermally, then sinter the part in a furnace. The metal particles fuse and the part shrinks to its final size.

Strengths: real metal parts without a laser powder-bed system. Safer handling than loose metal powder. Good for tooling, brackets and low-volume parts.

Limits: shrinkage must be scaled for in software, and thick sections take longer to debind. Parts keep some porosity, so properties are usually a little below wrought metal. Size is limited by the furnace.

Cost drivers: material, furnace cycles and the debinding step.

Metal FFF materials in the hub: 8. Tensile strength after sintering: 193–1,540 MPa (median 877.5 MPa, 6 materials).

See metal FFF materials 8 materials

How to pick a process

• Need a smooth, detailed look? Start with resin or PolyJet.
• Need tough functional parts in batches? Look at SLS or MJF.
• Need low cost, large parts or a specific polymer? FFF has the widest range.
• Need very large parts? Consider pellet extrusion.
• Need metal? Bound-metal FFF is the accessible route.

Browse all filaments 270 materials