Just as sophisticated urethane dispensing machines and CNC machine centers have found their way into polyurethane facilities, additive fabrication and rapid prototyping are gaining popularity in polyurethane processing, especially with these techniques’ ability to cut down on development time and costs.
Here’s a quick overview of some of the most promising rapid prototyping technology.
Stereolithography (SLA) and Selective Laser Sintering (SLS)
Both SLA and SLA start with precise 3D CAD data. The SLA machine builds the part layer by layer with a special laser to cure the liquid photopolymer to create a master. With the SLS, there is no liquid photopolymer. The materials range from wax to certain nylons and metals creating a more durable master. Watch for SLA’s latest nickel plating technology, which produces a strong, mirror finish that’s even waterproof.
Polyjet (Objet) and Fused Deposition Modeling (FDM)
The key to Polyjet technology is a special inkjet with a built-in UV laser spraying to build each layer. Similarly, FDM feeds a plastic, wire-like filament unwrapped from a supply coil to a heated extrusion nozzle with an on-off valve spraying liquid polymer layer by layer. Polyjet is new and more costly than other processes featured here, but it has a niche for building small parts that require fine details. FDM offers more flexibility in polymers, with tradeoffs between strength and service temperature.
Electron Beam Melting (EBM)
EBM uses a high-energy, precisely focused electron beam to melt fine metal powders layer by layer. The resulting product is solid and doesn’t require any additional thermal treatment. This makes EBM not only faster, but allows it to build high-definition masters and products.
Reminder: Polyurethanes are not metals, so plan accordingly. In fact, urethanes have a thermal expansion coefficient 10 times that of most industrial metals! Be sure to take such factors into account and design smart to avoid big problems and delays in production.