The Best 3D Printed Elastomers for Machining
It's possible to machine 3D-printed elastomers efficiently — but it takes the right materials
Elastomers are, by nature, flexible. While this property is desirable in their many applications, it creates a number of manufacturing challenges when it comes to parts that must be machined.
Because elastomeric parts are commonly used in applications that are expected to wear out eventually, like seals, they are frequently needed in low volumes for use as spare parts. Therefore, 3D printing makes financial sense.
There are some mechanical advantages to a manufacturing process that combines 3D printing and machining. Lathing offers more precision than what is achievable via additive manufacturing. Milling after printing also reduces waste without interrupting part quality or customer expectations. However, machining 3D printed materials poses some obstacles.
Why Is It Hard to Machine Elastomers?
Fragility
Additive manufactured elastomers have historically been weak. Porous material has inherent faults, and it can be deformed beyond its ability to rebound (not to mention causing problems down the road, once the part is in use).
During machining, delamination is another risk for 3D-printed elastomers. In parts printed via deposition, the layers can shear apart under force.
Tooling Inaccuracy
Even if an elastomer stands up to tooling without being permanently deformed, flexible material makes for a challenging work surface. Elastomers not only move away from tooling pressure but also rebound. Too much wobble, warp or stretch creates dimensional inaccuracies and imperfections. It's therefore difficult to achieve fine features or tight tolerances when machining most elastomers.
Time Consuming
Overcoming the aforementioned challenge makes for a slow manufacturing process. For a shop that charges $200 per hour, machining a finicky elastomeric part adds up to substantial time and money lost compared to a sturdier elastomer that could be machined in one third of the time, for example.
Image: Dust Cover for Leveling Valve with Machined Holes
Wear & Tear
A longer machining process also means more wear and tear on tools. Additive manufacturing shortens this process because the amount of material that must be removed to produce a final part is reduced.
How to Machine Elastomers Efficiently
Use More Durable, Stable Elastomers
Instead of sending ruined material to the scrap pile, start with fully dense elastomers. Chromatic's RX-AM™ printing process involves in-situ polymerization of reactive liquid materials during the printing process, which creates crosslinked urethanes. Available in a range of hardnesses, including Shore 70 and harder, these isotropic parts are more stable, offering more durability and ease of machining. They are immune to delamination and allow for greater dimensional accuracy.
Start With Near-Net-Shape Parts
RX-AM excels at near-net-shape manufacturing, where the initial shape of the part is close to the final desired geometry and requires minimal finishing. Minimizing subtractive manufacturing processes saves not only material but also time. Furthermore, less machining translates to less wear and tear on tools.
Applications
With RX-AM technology, manufacturers can start with isotropic printed components, then machine holes and other features to create custom parts. The process enables small-volume production of robust industrial parts with geometries and details that can be difficult to achieve through conventional machining of elastomers.
Parts produced using the RX-AM process exhibit superior mechanical properties compared to 3D-printed thermoplastics, including improved durability and resistance to wear, making them ideal for demanding applications. Chromatic's innovative approach to producing elastomers that are suitable for machining therefore has broad applications across various industries, including automotive, aerospace, medical and consumer goods.