Axtra3D Presents Its Expertise in 3D Printed Silicone Molds at Formnext

The Formnext booth centered on hybrid photosynthetic polymerization, or HPS. This process separates the light source from the resin vat, so the projector and the motion system no longer trade off against each other. In practice that means a larger build area than a standard top-down SLA machine of the same footprint, with throughput measured in parts per hour rather than layers per hour.

The printed object here is not the production part. It is the silicone mold that a cast urethane or epoxy part comes out of. Print the master, cast silicone around it, cure, cut the mold open, then pour the resin. That sequence is what the presentation was really about, and it is the part that matters to anyone doing low-volume tooling.

Resolution and surface quality come from the light engine. A printed master at Ra 0.8–1.6 μm transfers most of that texture into the silicone, and the silicone transfers it again into the cast part. Two transfers mean two chances to lose detail, so the print has to start clean.

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  HPS print engineSeparate light source and vat, larger build area
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  Printed outputA master pattern, not a finished mold
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  Final partCast urethane or epoxy from silicone tooling

Silicone molds suit parts with undercuts, thin walls, and organic geometry that would need slider work in steel. A printed master can include a boss, a snap hook, or an internal rib that a two-part machined mold cannot release. The silicone flexes enough to strip the part, and that flexibility is the whole point.

The economic window is roughly 20 to 200 castings. Below 20 parts, a printed or CNC-machined master plus a hand-poured silicone mold is usually the fastest route to a physical sample. Above a few hundred parts the silicone starts to tear, flash grows, and dimensional drift shows up in the castings. At that point a machined aluminum tool or a steel tool wins on cost per part.

Silicone tooling also fits when the design is still moving. Change a wall thickness or a radius, reprint the master, and a new mold is ready in days. A steel tool would need welding, re-machining, and re-spotting, which is a different order of cost.

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  Good fitUndercuts, thin walls, 20–200 castings, moving design
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  Poor fitTight tolerances, high temperature, 1,000+ parts
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  Not a fit at allHard tooling for a part that must hold ±0.05 mm

A printed master carries layer texture and stair-stepping on shallow angles. If the visible surface of the cast part is a Class A face, the master usually needs sanding and polishing before silicone is poured. That hand work eats the time the print saved. A machined master comes off the machine closer to final, especially on flat and cylindrical faces.

For masters larger than a few hundred millimeters, machining is often the only practical route. Our 5-axis centers cut up to 4,000 mm, with a Ø400 mm rotary table for contoured work, and hold ±0.005 mm. A printed master at that size would need to be split and bonded, and the bond lines show up in the casting.

Tight features push the same way. A master with a 0.5 mm rib or a sharp internal corner is easier to cut in aluminum 6061 than to print and clean. The machining side also gives us a master that can be reused for a second silicone mold after the first one wears out.

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  Choose machiningClass A surfaces, large masters, sharp internal corners
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  Choose printingOrganic shapes, small runs, fast design iteration
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  Often bothPrinted prototype, machined master for the tool

Silicone shrinks during cure, and urethane shrinks as it sets. Together they can pull a nominal dimension by 0.3% to 1.0%. That is a mold-level correction, not a print-level one. If the drawing says ±0.1 mm, the tool has to be built oversize to compensate, and the compensation has to be measured, not guessed.

Wall thickness drives warpage more than any other variable. A cast urethane part with a 4 mm wall and a 1 mm wall in the same shot will bow at the thin section. Keep walls within about 2:1 of each other, or accept that the part will need fixturing after demold.

Vents and a pour gate belong in the master design, not added later. Trapped air in a closed silicone mold shows up as short shots at the last-filled corner. We model the gate at the thickest section and vent the perimeter, then print or machine the master with those features in place.

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  Shrinkage0.3%–1.0% combined, correct it in the tool
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  Wall ratioKeep within 2:1 to limit warp
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  Gate and ventsDesigned into the master from the start

A conference demo shows the ceiling of a process. Your part lives at the floor, where draft angles, gate placement, and shrinkage decide whether the casting fits. That is why we ask for the 3D file and the drawing before quoting, and why we send a DFM note back with the quote.

GreatLight runs both sides of this decision. We print masters on our additive line, cut masters and aluminum tools on 127 CNC machines, and pour silicone and urethane in-house. One supplier means the master and the tool are held to the same tolerance stack.

Quotes and free DFM analysis come back within 12 hours, and production can start within 24 hours of approval. Parts ship in 3–5 days for most machined work. Uploads stay confidential, and we sign an NDA on request.

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  Send3D file, 2D drawing, target quantity, resin type
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  Get backQuote, DFM note, tooling recommendation
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  CertificationsISO 9001:2015, IATF 16949:2016, ISO 13485:2016, ISO 27001:2022