Your Guide to Formlabs Flexible Resin

Flexible Resin

Formlabs’ library of materials for the Form 2 3D printer is extensive. Users can choose Standard resin for astonishing detail and low cost parts, or a Functional resin for something a little different.

All Formlabs resins, which at the time of writing include Standard, Flexible, Dental SG, Castable and Tough, serve a purpose – whether that’s for creating snap-fit joints or dental surgery guides. Today, we are going to take a closer look at Formlabs Flexible Resin, which is one of our favourites. Flexible Resin is used mainly for ergonomic and functional prototypes but it can also be used for end-use parts. So without further ado, let’s take a closer look at Flexible Resin:

Editor’s note: There are two versions of Flexible Resin. The new version or version 2 (FLGRO2) is opaque black while the old version or version 1 (FLGRO1) is a transluscent grey. For the sake of clarity, in this article we will be discussing the new version, version 2 (FLGRO2).

Flexible Resin Characteristics

Formlabs Flexible Resin

Flexible Resin is a rubber-like material with elastomeric properties but low elongation. This means that parts are bendable and compressible but not stretchable.

Parts that are printed thin are pliable while parts that are printed thick are resilient. So the higher your need for impact resistance, the thicker parts should be. Denser parts are less bendable. The new version of Flexible Resin is more tear resistant and wear resistant than the old version. Its tensile strength post-cured is 7.7-8.5 MPa, with a tear strength of 75.7 lbf/in.

When printed, Flexible Resin feels very much like a silicone or rubber. Parts can be compressed and ‘bounce’ back to their original form. Obviously, Flexible Resin cannot shatter like standard filaments however it will tear if it is subjected to extreme stress. This means Flexible Resin is ideally suited to functional and ergonomic prototyping (information about applications can be found below).

Flexible Resin Applications

The excellent compression characteristics of Flexible Resin make it the ideal print material for high impact applications. This is a versatile and tactile material ideally suited to ergonomic prototyping and functional prototypes, and even end-use parts, that require elastomeric properties.

Flexible Resin can be used to 3D print custom grips and holds, gaskets, overmoulds, stamps, cushioning and dampening and wearable prototypes, such as shoe insoles. It can also be used to simulate soft-touch materials, such as the silicone grips found on some sports drinks bottles.

What Flexible Resin isn’t suitable for is obvious; due to its low elongation, it is not suitable for simulating stretchy materials and it is not suitable for very fine details or features because it can only be printed down to 50 micron, and it doesn’t show the same level of detail as Standard Resin. However, we have found that Flexible Resin can produce detailed prints. The picture at the top of this article of a drinking bottle is testament to this.

Flexible Resin Best Practices

Using Flexible Resin

The base thickness for parts printed with Flexible Resin should be at least 1.25mm however for larger pieces we and Formlabs recommend a base thickness of 2.20mm.

You will find that tall and thin parts are more difficult to print consistently with Flexible Resin because they flex during the peel process. To remedy this, you should orient your part closer to the build platform up to 20 degrees or add manual supports to the part. You can also test out the different advanced support settings available to you and adjust these during the print process to stop your larger model from flexing during the peel process.

Perhaps the most critical stage of printing with Formlabs Flexible Resin is the finishing stage. You should peel your part off the print bed slowly. You should then wash your model in IPA solution. For users of FLGRO2, you will find that the washing process is faster due to this version’s lower viscosity. There is also no need to post-cure your parts for a professional finish. This was required for the first version of Flexible Resin but not the latest version. It also washes faster and better in IPA than the first version.

Any questions? Get in touch!

We hope we have answered all the questions you have about Formlabs Flexible Resin with this guide. If we haven’t, simply contact us and ask us your question and we will get back to you as soon as possible.

Request A Free Sample