Binder Jetting
Binder jetting prints liquid binder into a powder bed to hold each layer, producing green parts that are later sintered or infiltrated.
- Part
- Forming
- Revised
- 2026-08-11
At a glance
- Family
- Additive Manufacturing
- Typical tolerances
- Roughly ±0.5% of dimension on sintered metal (about ±0.008 in on a 1.5 in feature), with ±0.3% achievable on well-characterized geometry. Binder-jetted foundry sand molds hold approximately ±0.012 in (±0.3 mm).
- Surface finish
- Ra 200–500 µin (5–13 µm) on sintered metal as built, dependent on powder size and orientation; machining or tumbling improves it. Sand molds are far rougher and impart their own texture to the casting.
- Typical volumes
- 50–50,000 parts for sintered metal; 1 and upward for foundry sand molds and cores
- Lead time
- 7–15 business days for sintered metal, most of it furnace scheduling and post-machining. Binder-jetted sand molds are frequently produced in 2–5 business days.
- Materials
- Metal, Ceramic, Composite
What it is
Binder jetting prints a liquid binder from inkjet heads into a powder bed, gluing each layer into a fragile "green" part that is later cured, depowdered, and then sintered or infiltrated to full strength. Nothing is melted during printing, which is the key to the process: there is no melt pool, no residual stress, no supports, and no requirement that the material be weldable.
Because whole layers are printed rather than scanned, binder jetting is among the fastest additive processes, with layers of 0.002–0.004 in (50–100 µm) for metals and 0.008–0.016 in (200–400 µm) for foundry sand. Metal parts shrink 15–20% linearly during sintering, and managing that shrinkage — rather than printing — is where the engineering effort goes.
The three commercial branches are metal (316L, 17-4 PH, low-alloy steels, copper, tungsten carbide), foundry sand molds and cores for sand casting, and full-color gypsum models. Volumes range from one sand mold to tens of thousands of small sintered metal parts.
How it works
- Recoat. A roller or blade spreads a layer of powder — 0.002–0.004 in (50–100 µm) for metal, 0.008–0.016 in (200–400 µm) for silica sand.
- Print binder. A piezo inkjet carriage traverses the bed, jetting binder only where the cross-section is solid. Print speed depends on carriage passes, not on cross-sectional complexity, so a bed full of parts prints little slower than one part.
- Cure in place. For metal systems the bed is warmed (commonly around 180–200 °C / 355–390 °F) to polymerize the binder and give the green part enough strength to be handled. Sand systems cure at or near room temperature with a furan or phenolic binder and an activator.
- Depowder. The green part is dug out and cleaned with brushes and low-pressure air. Green strength is comparable to chalk; this is the most fragile point in the whole workflow and drives minimum wall thickness.
- Debind and sinter (metal only). The part is set on ceramic setters and run through a furnace cycle that first burns out the binder and then sinters the metal — around 1,350–1,400 °C (2,460–2,550 °F) for 316L. The part shrinks 15–20% in every direction and typically reaches 96–99.5% density.
- Compensate and verify. The printed geometry is scaled up by the expected shrinkage before printing, and thin or overhanging sections need setters or sacrificial supports to stop them sagging under gravity at sintering temperature. First-article iteration on the scaling factors is normal.
- Finish. Sintered parts can be machined, plated, or polished conventionally. Sand molds go straight to the foundry; color models are infiltrated with cyanoacrylate or resin for strength.
Design guidelines
Design for sintering, not for printing
The printer will make almost anything. The furnace will not. Long unsupported spans, heavy sections cantilevered off thin ones, and large flat plates all sag or distort at sintering temperature. Keep sections uniform, support long horizontal features on setters, and expect the first article to reveal distortion the CAD model did not.
Uniform wall thickness
Non-uniform sections shrink at different rates and pull the part out of shape. Aim for constant wall thickness the way you would for metal injection molding — the sintering physics is essentially the same.
Wall thickness
Green strength sets the floor: 0.040 in (1 mm) minimum for metal, and 0.080 in (2 mm) if the part is large or will be handled much before sintering. Sand molds work at far heavier sections.
Shrinkage and tolerance
Plan for 15–20% linear shrinkage in metal, applied as a scaling factor. Achievable tolerance is proportional — roughly ±0.5% of dimension after sintering, sometimes ±0.3% on well-characterized geometry. Any feature needing better than that must be machined afterward, so add stock.
Holes and threads
Sintering closes small features. Keep holes at 0.060 in (1.5 mm) or larger, and machine or tap all threads after sintering — see the tap drill chart for pilot sizes, remembering the pilot must be scaled up for shrinkage before printing.
Powder removal
Enclosed cavities hold un-bonded powder that must be removed while the part is still green and fragile. Provide generous access ports of 0.20 in (5 mm) or more.
| Feature | Recommended | Limit | Why |
|---|---|---|---|
| Wall thickness (metal) | 0.080 in (2 mm) | 0.040 in (1 mm) | Green strength during depowdering |
| Hole diameter | 0.12 in (3 mm) | 0.060 in (1.5 mm) | Sintering closes small features |
| Section uniformity | Within 2:1 | 3:1 | Uneven shrinkage distorts the part |
| Unsupported span | 0.8 in (20 mm) | Support on setters | Gravity sag at sintering temperature |
| Powder escape port | 0.30 in (8 mm) | 0.20 in (5 mm) | Green part cannot be shaken hard |
| Machining stock | 0.020 in (0.5 mm) | — | Sintered tolerance is proportional |
Cost drivers
Binder jetting has the best throughput economics of any metal additive process at quantity, because printing is fast, nothing is scanned point-by-point, and the bed can be packed in all three dimensions with no supports. Per-part cost falls steeply with nesting density and then flattens.
Against that, the furnace is a fixed cost and a fixed risk. Sintering runs take many hours, setters and sacrificial supports are consumable, and yield loss from distortion is a real line item on new geometry until the shrinkage compensation is dialed in. Development cost for a first article is therefore higher than for laser powder bed fusion, and unit cost at volume is lower.
For foundry sand, the economics are different again: binder jetting replaces pattern and core box tooling entirely, so a one-off casting that would have needed a wooden pattern becomes economic, and complex cores that no pattern shop could draft become routine.
Volume breakpoints: metal binder jetting is generally uncompetitive below about 50 parts (development and furnace overhead) and increasingly attractive from a few hundred to tens of thousands, where it competes directly with metal injection molding — without MIM's tooling cost.
- Design uniform sections; distortion, not printing, drives scrap.
- Nest densely — you pay for bed volume and furnace space.
- Batch parts of the same alloy so they share a sintering run.
- Accept ±0.5% tolerance everywhere you can, and machine only the features that need better.
- For casting work, use binder-jetted sand to delete pattern tooling entirely rather than to copy an existing pattern.
Questions
7 questionsHow much do binder jetted metal parts shrink?
15–20% linearly during sintering, in all three axes. The printed geometry is scaled up by that factor beforehand, but shrinkage is only uniform if wall sections are uniform — which is why design for sintering matters more than design for printing in this process.
What tolerance can metal binder jetting hold?
About ±0.5% of the dimension after sintering, and ±0.3% on geometry whose shrinkage behavior has been characterized through first articles. That is proportional rather than absolute, so large parts have large tolerance bands. Critical features are machined afterward.
Does binder jetting need support structures?
Not during printing — the surrounding loose powder holds everything, and there is no melt pool or residual stress. Sintering is a different matter: long unsupported spans sag under their own weight at furnace temperature and need ceramic setters or sacrificial supports.
How dense are binder jetted metal parts?
Typically 96–99.5% after sintering, depending on alloy and cycle. That is below laser powder bed fusion, so fatigue properties are lower, but it is comparable to metal injection molding and adequate for a wide range of structural and consumer applications.
Why is binder jetting used for foundry sand?
It prints molds and cores directly from CAD with no pattern or core box, which removes pattern tooling from the casting cost entirely and allows core geometry that could not be drawn from a box. Layers of 0.008–0.016 in (200–400 µm) make it fast enough for full-size molds.
How does binder jetting compare with metal injection molding?
The debinding and sintering steps are nearly identical, and so are the design rules and achievable densities. The difference is up front: MIM needs an injection tool and pays back over tens of thousands of parts, while binder jetting needs none and is competitive from a few hundred parts upward.
Why are binder jetted green parts so fragile?
Only polymer binder holds the powder together before sintering — green strength is on the order of chalk. That is why minimum walls are 0.040–0.080 in (1–2 mm), why depowdering is done gently by hand, and why the cure step before depowdering is not optional.