Genera Uses 3D Printing to Overturn Eyeglass Frame Manufacturing

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  How Genera Uses 3D Printing to Build a Frame
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  What Sets the Dimensional Result in DLP and SLA
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  Where 3D Printed Frames Hold Up and Where They Do Not
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  Pairing Printed Frames With CNC Machining
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  Which Resin or Metal Fits the Frame
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  3D Printing vs CNC vs Injection Molding for Frames

Genera uses 3D printing in a vat photopolymerization format. A projector or laser cures liquid resin layer by layer on a build platform that rises or drops by a fixed step. For eyewear, that step usually sits between 25 μm and 100 μm. The finished green part is washed in solvent, then post-cured under UV so the polymer reaches its final stiffness and color.

The commercial shift is not the printer itself. It is the file. A frame model moves from CAD to print in hours, so a temple length, a bridge width or a lens groove can change without touching a mold. That is what breaks the traditional model: no steel mold, no minimum run of thousands, no tooling lead time to amortize.

The process runs on two main resin families. Standard acrylate resins give a matte, slightly flexible frame at low cost. Engineering resins add ceramic or rubber domains and hold up better against sweat, sunscreen and repeated hinge flex. Neither behaves like acetate, so the design has to account for that from the start.

Layer height controls vertical resolution; pixel or spot size controls horizontal resolution. On a DLP machine, the projected pixel might be 50–75 μm, so a thin rim edge or a lens groove gets stair-stepped at that scale. On an SLA machine, the laser spot is often smaller, which helps fine geometry but slows the build.

Shrinkage is the quiet variable. Resin cures and contracts, and thin walls pull differently than thick ones. A frame front with a 2 mm rim and a 6 mm bridge will distort unevenly unless the model is compensated. Good shops print a test coupon first, measure it, and offset the CAD before the real run.

Orientation matters as much as the resin. Frames printed flat on the platform hold the front face well but sag at the temples. Frames tilted 20–30° trade surface quality on the front for straighter temples. Support marks land wherever the supports touch, so the touch points go on the inside of the rim, never on the lens seat.

Printed frames win when the geometry is organic, the run is short, or the design is still moving. A rim with an undercut, a lattice temple, or a hinge pocket that would need a slide in a mold is almost free to print. A run of 50 to 500 units with three colorways is a natural fit.

They lose when the requirement is a hard, thin, optically critical part. A lens seat that must hold ±0.05 mm across a 50 mm front is hard to guarantee in resin, because cure shrinkage and post-cure warp stack up. Metal frames, or a printed frame with a machined lens ring, handle that better.

They also lose on the hinge. A printed living hinge or a printed pin boss takes repeated load poorly. Most durable designs use a printed front and temples plus a bought-in metal hinge, screwed or riveted in. The print carries the shape; the metal carries the fatigue.

Printing and machining are not rivals here. A common route is to print the frame body, then machine the lens ring, the hinge seat or the nose pad insert to a tighter tolerance. The printed part gives the shape and the low tooling cost; the machined insert gives the fit that a wearer feels every day.

For a metal-acetate look, the printed front can be finished by bead blasting, tumbling or polishing, then anodized or dyed. Surface finish on a printed part typically lands around Ra 3.2–6.3 μm off the platform. Light bead blasting brings that down and hides layer lines at the same time.

At GreatLight we run 127 high-precision CNC machines, including 16 simultaneous 5-axis centers, so a printed frame can move straight into a machined hinge boss, a threaded insert or a lens ring without a second supplier. Tolerance on those machined features holds at ±0.005 mm.

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  Print for shapeOrganic rims, lattice temples and short runs with no tooling.
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  Machine for fitLens ring, hinge seat and nose pad insert held at ±0.005 mm.
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  Finish for feelBead blasting, tumbling or polishing to cut layer lines.

For a concept frame, a standard acrylate resin is enough. It prints fast, takes dye well and costs little. Use it when the goal is to check proportion, bridge width and how the temple sits behind the ear. Do not use it for a wear test in summer.

For a functional prototype, pick an engineering resin with higher elongation and better UV stability. These hold shape after weeks of handling and survive a hinge cycle test. They still creep under constant load, so a printed temple that is pre-loaded against the head will slowly relax.

For a metal frame, the printed route is different. SLM prints in titanium or stainless, but the surface comes out rough and needs support removal, then machining on the hinge and lens ring. That path costs more than resin printing but gives a frame that behaves like metal because it is metal.