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VPP Practical
| Question | Answer |
|---|---|
| What are the components of a VPP resin? | Photoinitiators: absorb UV light and produce reactive species (initiate process). Liquid monomers: smallest building blocks of the final polymer network. Oligomers: larger, pre-formed polymer structure that can still be crosslinked further - determine man |
| What is the purpose of ______ this component? | Build plate, Z-Axis or “Elavator”, Removable support, resin level float, build tank, curable resin, recoater, flexible and laser transparent membrane, scanning galvanometers, uv laser.??? |
| The upgraded Form 3 uses a Light Processing Unit (LPU), with a single galvanometer compared to dual galvanometers in the Form 2. How does the LPU operate to allow for scanning in two dimensions with a single galvanometer? What issue has the LPU solved? | LPU uses a parabolic mirror making the laser perpendicular to the surface. This solves the changing resolution in xy plane. |
| Describe two material properties that can be achieved with resins but not with FFF filament. | Higher resolution, increased heat resistance |
| Describe Stefan Adhesion and its effect on minimum feature size for VPP. | The printed/cured layer will adhere to the membrane that separates the resin tank from the laser optics. Parts must be strong enough to not separate at their layers during the peeling process |
| Describe at least two properties a resin printing film must possess. | Transparency to allow UV light to pass through. Smooth Surface Finish so that there's a a uniform and level base for each layer of resin. flexible film for the peeling action. |
| Name one specialty resin that FormLabs offers (not black or drafting resin) and an application. | Permanent Crown Resin for 3D printing permanent single crowns, inlays, onlays, and veneers |
| What is perhaps the most compelling reason to use resin printing over FFF? | Higher resolution |
| Are resin prints watertight? Are they food safe? | They are watertight. Depending on the resin, they can also be food safe. |
| Why is bottom-up orientation most popular for VPP? | Shallow vat less material required. Part height is not limited to the vat depth. Layer thickness controlled by the elevator and not by the resin fluid properties |
| When is top-down orientation used for VPP? And what are the drawbacks? | Laser shines from above? Large starting volume of resin. Downward movement of the platform disrupts the equilibrium of the resin level (takes time to recover). Difficult to control the layer thickness since only gravity is involved in leveling surface |
| Why do VPP prints have to be post cured? | After printing, uncured resin remains within the model. Uncured monomer decreases mechanical properties and causes a tacky finish |
| What is one benefit and drawback to long post cures? | The post curing improves the mechanical properties of the print. Significant warping can occurs during post-curing. |
| Describe the difference between mask project (or DLP) and point wise VPP? What limits the resolution of each technique? | Mask project emits pixels that are either on or off which creates the model one layer at a time. The resolution is limited by the pixel size. Point-wise means that a laser is traced along the outline of the model. Limited by spot size and xy morphing |
| Why do VPP prints warp? What is a method to combat this? | When resins photopolymerize, the polymeric chains are closer together than the monomer, causing the printed part to shrink and warp. Scan Patterns: Star-WEAVE greatly minimized RS |
| Describe the dead zone in CLIP and how it results in a 10x-100x faster print speed than most VPP processes. | The dead zone's a thin layer of uncured liquid between the oxygen-permeable window and the curing part surface. CLIP eliminates the time-consuming steps of resin exposure, renewal, and part movement |
| (Picture) Name this print failure and state the cause. | ___ |
| When a print failure occurs parts/section of the print are often missing. Were they printed, if so, where are they? How do you clean up a print failure? | They may be stuck to the film. We print a mesh. |
| How much more does a black resin printed part cost compared filament printed part of similar? | About 7-8 times as much. 1kg of PLA is $20 and 1 L of resin is $150 |
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