A viewer under Protolabs’ MJF explainer wanted a nylon battery carrier. Their question: how will the part handle 60 °C? Will it deform? It’s quite thin. That last detail matters more than the temperature, and it’s why MJF PA12 heat resistance is harder to read off a datasheet than it looks.
What does MJF PA12 heat resistance look like at 60 °C?
On the numbers, yes, with room to spare. HP’s datasheet for HP 3D High Reusability PA 12 lists a heat deflection temperature of 95 °C at 1.82 MPa and 175 °C at 0.45 MPa, the same in XY and Z. The powder’s melting point is 187 °C. A 60 °C battery bay is well below all of those.
So why worry about a thin part?
Because HDT is one test on one bar shape. It tells you the temperature at which a standard test bar bends a set amount under a fixed load. A thin wall carrying a battery’s weight for hours is a different situation. A part that’s stiff at room temperature can still creep under a steady load below its HDT. HP’s datasheet doesn’t list creep data, and I haven’t found an HP source that gives a long-term service temperature for PA12, so don’t let anyone quote you one as fact.
Thin parts also start out with less margin. HP’s design handbook warns that thin, long parts are prone to warpage from shrinkage in the first place. If a wall comes out of the build with a slight bow, heat and load will find it.
What should you change in the design?
Give the walls something to lean on. HP’s handbook suggests thickening long walls to cut their aspect ratio. Add ribs where the battery’s weight sits, and avoid thin cantilevers that carry the load. Clips that hold the battery under constant spring force deserve the most attention, since that’s exactly the load case that creeps.
How do you prove it before shipping?
Put a printed part in an oven at 60 °C with a real battery or an equal weight in it. Leave it overnight, then measure the clip gap and flatness against a part that stayed at room temperature. If the clip’s opened up, add material there and test again.
Related on the Solvi blog: PA11 vs PA12 on MJF: When Is PA11 Worth Running?; MJF Warping: Why Large Flat Parts Warp; MJF Watertight Parts: Can PA12 Hold Water Under Pressure?.
Sources: YouTube: What is Multi Jet Fusion and how does it work? (Protolabs), viewer question; HP 3D High Reusability PA 12 datasheet (PDF).