Smart Molding International 1-2026

49 www.smart-molding.com addi ve manufacturing • Reduced dimensional stability • Reduced chemical resistance • Decreased resistance to hydrolysis • Increased permeability Design & Material Limita ons Colder build chambers will also limit what geometries and materials can be printed. Everything from print settings to part design, size, orientation, and placement in build volume will affect regional thermals. As a result, lots of manual tuning and testing will likely be required on a per part basis. Warping/Cracking and Dimensionally Accuracy Issues As a polymer is heated in the hotend, expansion occurs. Once extruded, if the chamber temperature is not held within the polymer’s processing window, the printed bead quickly cools and contracts. If a bead’s full contraction is inhibited by the previous layer, printed-in stress occurs, and if it becomes too great delamination and warping occur. Annealing Assuming you’re able to print a part without warping or cracking, annealing is a commonly recommended post-processing step to improve part properties, but there are a few caveats to consider: • Annealing benefits are mostly limited to semi-crystalline polymers (PA, PAEK, PEEK, PEKK, PP, PPS). For amorphous polymers, like ULTEM™, annealing offers little to no improvement in mechanical properties. • As a part is heated, areas with higher residual stress are likely to shrink more than areas with lower stress, causing the part to deform and warp. • As printed beads relax, shrinkage is likely to occur in the XY direction, causing dimensional accuracy issues. Conclusion PEEK, ULTEM, and other high performance polymers offer metal-like strength/stiffness, continuous use temperatures up to 250°C, and extreme chemical resistance — unlocking a wide range for tooling and end-use additive applications — with many companies recouping their hardware investment in months, not years. While many printers claim they can print these materials, a large portion lack the chamber thermals and convection profiles to print them reliably. AON3D www.aon3d.com Vortex (Recommended) Two air currents are fed into the build volume from adjacent corners, in a vortex fashion, with the outlets opposite to each respective inlet. Converging Two converging air currents meet at the center of the build area, while chamber air is pulled out near the bottom of the build chamber. Blade A blade of air is passed across the build volume, at the height of the extruder, exiting the build volume on the opposite side. In a 2019 study at the University of Texas, researchers evaluated the impact of build chamber temperature on interlayer weld strength with unreinforced and carbon-fiber reinforced PEEK. They found that increasing the chamber temperature from 150 °C to 250 °C resulted in up to a 287% increase in Z-direction strength. In the diagram below, you can see how maintaining a high build chamber temperature during the printing process (right), and letting all layers cool together, will result in uniform contraction, resulting in more dimensionally accurate parts.