Specifying a flexible part raises the immediate question of hardness, great if you can specify this, a problem if you can’t!
Plunkett Associates have a durometer in their office, so if you have a sample and send it to them. They are quite happy to measure it, supply a quote and return the sample with the prototypes.
They appreciate specifying your requirement is the most difficult phase, especially early in the prototyping stage, and are here to help.
If 3D Printing, it is often significantly cheaper to run multiple hardnesses at the same time, i.e. bracket the target hardness, remembering that most figures quoted are ±5 points on the Shore A scale.
With PU castings this can also be done, as there is negligible impact on the tooling. Unfortunately the cost benefits of doing this with 3D printing do not apply. Still, ordering a couple of extra parts either side of the predicted hardness, can be very effective and a good insurance policy!
PU parts and 3D printed parts can all offer a range of hardnesses. PU is typically available from around 35 – 90 Shore A and 3D printing from 27 Shore A upwards.