We previously tested the V4 resins for parts with small screw bosses, but they would break very easily when a screw was inserted. Is the V5 resin any better in this regard?
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It should be better, but plastic thread-forming screws are still going to be challenging. Looking at the material properties, Grey V5 has significantly improved mechanical strength compared to Grey V4, which should help with screw boss performance.
| Property | Grey V5 (Post-Cured) | Grey V4 (Post-Cured) | Difference |
|---|---|---|---|
| Ultimate Tensile Strength | 62 MPa | 65 MPa | Similar |
| Tensile Modulus | 2675 MPa | 2800 MPa | Slightly lower in V5 (more impact resistant) |
| Elongation at Break | 13% | 6% | V5 is over 2x as ductile, meaning less brittle failure |
While these improvements should help, the best approach is still to use self-tapping screws for plastic, rather than standard thread-forming screws, as those will likely still cause stress concentrations that could lead to cracks or failure.
I’ve attached screenshots of the full material properties for both Grey V5 and Grey V4 for reference.
Grey Resin V5:
Grey Resin V4:
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That’s great thank you!
We make an input device that utilizes 15 thread forming screws. We had a lot of problems with V4 but resolved that by adding 0.2mm (200 microns) to the diameter and have had zero issues in either V4 or V5 since. We also added ribs to the bosses and widened them as much as possible. This may not work for you if you are trying to prototype injection molded parts.
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