{"id":6005,"date":"2026-05-07T14:00:48","date_gmt":"2026-05-07T14:00:48","guid":{"rendered":"http:\/\/localhost:10016\/blog\/sls-vs-3dp-sand-printing\/"},"modified":"2026-09-24T09:23:14","modified_gmt":"2026-09-24T09:23:14","slug":"sls-vs-3dp-sand-printing","status":"publish","type":"post","link":"https:\/\/www.lyafs.com\/fr\/blog\/sls-vs-3dp-sand-printing\/","title":{"rendered":"SLS ou impression 3D sur sable pour les fonderies : quelle technologie l'emportera en 2026 ?"},"content":{"rendered":"\n

Two names dominate the sand 3D printing conversation in foundries: SLS and 3DP. Both turn a CAD file into a sand mold or core without tooling \u2014 but they are completely different machines, with different accuracy, speed, material costs, and sweet spots. Pick wrong, and you either pay precision pricing for parts that did not need it, or you try to hold a tolerance your process cannot reach.<\/p>\n\n\n\n

The good news: after a decade of real production use, the decision rule is now clear. This guide compares selective laser sintering (SLS) and inkjet binder jetting (3DP) for sand casting \u2014 accuracy, speed, strength, cost per mold, and the applications each one actually wins. By the end you will know which process fits your parts, and when the smartest move is to use both.<\/p>\n\n\n\n

This is not a marketing comparison. Both technologies are in daily production at foundries around the world, and both have clear, defensible use cases. We will also cover the hybrid workflow that leading foundries increasingly run \u2014 using 3DP for the mold and SLS for the cores \u2014 because in 2026 the question is rarely “SLS or 3DP” but “which one, for which part.”<\/p>\n\n\n\n

\"Industrial<\/figure>\n\n\n\n

What SLS and 3DP Sand Printing Actually Are<\/h2>\n\n\n\n

The two processes look similar from the outside \u2014 a machine spreads sand, then builds the shape layer by layer \u2014 but the binding mechanism is fundamentally different.<\/p>\n\n\n\n

3DP (binder jetting)<\/strong> uses a printhead that selectively deposits liquid binder onto thin layers of foundry sand, the same way an inkjet printer puts ink on paper. The sand stays loose except where the binder lands, and the mold or core is solid when the build finishes. 3DP systems print with furan or phenolic binders and produce molds at high volume \u2014 3DPTEK’s large-format printers are rated in liters per hour, not cubic centimeters. For the full technical breakdown, see our binder jetting technical guide<\/a>.<\/p>\n\n\n\n

SLS (selective laser sintering)<\/a><\/strong> replaces the printhead with a laser. The machine spreads a pre-coated sand \u2014 sand particles already coated with a resin layer \u2014 and the laser sinters the resin wherever the part should be solid. Because a laser can be positioned more precisely than a binder printhead, SLS sand molds and cores hold tighter tolerances, but the laser also makes the process dramatically slower and limits the build volume. SLS sand printing is the technology behind 3DPTEK’s LaserCore-5300<\/a> and LaserCore-6000<\/a> machines.<\/p>\n\n\n\n

If the sand printing fundamentals are new to you, start with our 7-step guide to how sand 3D printing works<\/a>, then come back to the comparison.<\/p>\n\n\n\n

Accuracy: SLS Wins the Tolerance Race<\/h2>\n\n\n\n

Accuracy is the single clearest differentiator between the two processes.<\/p>\n\n\n\n

SLS sand printing holds device accuracy of \u00b10.1 mm on features up to 100 mm<\/strong> and \u00b10.1% beyond that \u2014 roughly pattern-quality tolerance, straight from the printer. The 3DP inkjet line holds \u00b10.3 mm up to 300 mm<\/strong> (and \u00b10.5 mm above that) on the J1800\/J1800S\/J2500 class, with the large-format J4000 and J4000Pro rated at \u00b10.5 mm up to 500 mm and 0.1% beyond. In other words, SLS is roughly three times more precise on small features.<\/p>\n\n\n\n

But precision has a context. Most sand castings carry drawing tolerances in the \u00b10.5\u20131 mm band, and both processes hold that comfortably. SLS precision only becomes the deciding factor when the feature itself is small \u2014 thin sections, fine surface detail, or cores whose internal geometry must register tightly against the mold. If your parts are standard foundry work with tolerances in the millimeter range, the accuracy gap will not show up in the castings.<\/p>\n\n\n\n

Surface finish follows the same pattern. SLS works with layer thicknesses of 0.08\u20130.35 mm, while production 3DP sand printing runs at 0.2\u20130.5 mm. Finer layers mean smoother walls and crisper detail on thin sections \u2014 a 0.08 mm layer leaves a far finer step pattern on the casting surface than a 0.4 mm layer. For cosmetic or near-net surfaces on precision castings, that is a real advantage; for machined or shot-blasted surfaces, it rarely matters.<\/p>\n\n\n\n

Speed & Build Volume: 3DP Wins at Scale<\/h2>\n\n\n\n

This is where the two technologies diverge most sharply, and it drives almost every cost comparison that follows.<\/p>\n\n\n\n

Metric<\/th> SLS (LaserCore-5300)<\/th> SLS (LaserCore-6000)<\/th> 3DP (J2500)<\/th> 3DP (J4000)<\/th> <\/tr> <\/thead>
Build volume<\/td> 700 \u00d7 700 \u00d7 500 mm<\/td> 1,050 \u00d7 1,050 \u00d7 650 mm<\/td> 2,500 \u00d7 1,500 \u00d7 1,000 mm<\/td> 4,000 \u00d7 2,000 \u00d7 1,000 mm<\/td> <\/tr>
Forming speed<\/td> 150\u2013400 cm\u00b3\/h<\/td> 80\u2013300 cm\u00b3\/h<\/td> 14\u201320 s\/layer<\/td> 130\u2013360 L\/h<\/td> <\/tr>
Layer thickness<\/td> 0.08\u20130.35 mm<\/td> 0.08\u20130.35 mm<\/td> 0.2\u20130.5 mm<\/td> 0.2\u20130.5 mm<\/td> <\/tr>
Accuracy<\/td> \u00b10.1 mm (\u2264100 mm)<\/td> \u00b10.1 mm (\u2264100 mm)<\/td> \u00b10.3 mm (\u2264300 mm)<\/td> \u00b10.5 mm (\u2264500 mm)<\/td> <\/tr> <\/tbody> <\/table><\/figure>\n\n\n\n

Read the units carefully. SLS is measured in cubic centimeters per hour<\/strong>; production 3DP sand printers are measured in liters per hour<\/strong>. One liter is 1,000 cubic centimeters. A J4000 printing at its rated speed produces roughly as much bonded sand in a few hours as a LaserCore-6000 produces in a full week of running. The J4000Pro is another step up at 1,090\u20131,744 L\/h.<\/p>\n\n\n\n

SLS is also capped on part size: the largest SLS sand machine in the 3DPTEK range, the LaserCore-6000, has a 1,050 \u00d7 1,050 \u00d7 650 mm build box. Production 3DP machines reach 2,500 \u00d7 1,500 \u00d7 1,000 mm (J2500) and 4,000 \u00d7 2,000 \u00d7 1,000 mm (J4000), with the J4000Pro extending to 4,000 \u00d7 2,500 \u00d7 1,500 mm and flexible 4 m+ forming. If you print engine blocks, pump housings, or anything that does not fit inside a one-meter cube, SLS is not the answer \u2014 3DP is.<\/p>\n\n\n\n

Operationally, the speed gap changes how you schedule the floor. A J1800-class 3DP machine can batch several small molds in one build box and run on a production schedule, which makes it a daily tool rather than a specialty cell. An SLS machine is typically running one carefully scheduled precision job at a time, producing a fraction of the volume per cycle. If throughput is your constraint, the answer is 3DP; if tolerance is your constraint, SLS.<\/p>\n\n\n\n

\"3DP<\/figure>\n\n\n\n

Strength & Material Systems: SLS for Demanding Cores<\/h2>\n\n\n\n

Sand strength depends on the binder system, and here the two processes use different chemistry.<\/p>\n\n\n\n

SLS sand parts are built from pre-coated sand (coated sand)<\/strong> with a resin layer that the laser fuses. The result is high green strength \u2014 3DPTEK documents roughly 4\u20136 MPa<\/strong> flexural strength for SLS sand bodies, with sand cores from phenolic systems reaching \u22652 MPa bending strength<\/strong>, gas evolution \u226410 ml\/g<\/strong>, and a refractoriness of 1,500\u20131,700 \u00b0C<\/strong>. That combination \u2014 strong, low-gas, high-temperature \u2014 is why SLS sand cores are preferred for long, thin, heavily loaded core passages where a core must survive turbulent pouring without distorting.<\/p>\n\n\n\n

3DP sand molds and cores use furan or phenolic binders<\/strong> deposited at roughly 1.8\u20132.5% resin content, delivering 1.5\u20132.5 MPa tensile strength<\/strong> and gas evolution of 8\u201311 ml\/g<\/strong>. Furan systems serve aluminum, iron, and copper castings; phenolic adds hot strength for steel and high-temperature alloys. For most molds, 3DP strength is entirely sufficient \u2014 the mold carries the pour, not the other way around. The exceptions are slim, high-aspect-ratio cores where SLS’s higher strength and lower gas make the difference between a first-shot pour and a scrap core.<\/p>\n\n\n\n

\"SLS<\/figure>\n\n\n\n

This is why the two processes are rarely in direct competition on a well-run foundry floor. SLS handles the cores that carry the load; 3DP handles the mold that carries the pour. In the composite pipeline 3DPTEK runs in production, the external mold is printed on a 3DP machine while the internal pipeline cores are printed on a LaserCore SLS machine \u2014 each process doing the job it is best at.<\/p>\n\n\n\n

Cost Per Mold: Where Each Process Wins<\/h2>\n\n\n\n

Cost follows directly from speed and material. SLS is more expensive per kilogram of printed sand for three reasons: the coated sand feedstock costs more than loose foundry sand plus liquid binder; the machine is slower, so labor and floor-time per mold are higher; and the build box is smaller, so you cannot batch as many parts per cycle. As a rule of thumb, SLS precision sand costs several times more per mold than 3DP inkjet sand at production scale<\/strong>.<\/p>\n\n\n\n

That premium buys you something real \u2014 accuracy and strength you cannot get from 3DP at the same feature size. The economics resolve to a simple rule:<\/p>\n\n\n\n