PA11 vs PA12 for MJF Snap-Fits

Here's a snap-fit that has to open up and close again without cracking. PA11 vs PA12 is the material call that decides most of it.

Is Nylon 11 or Nylon 12 Better for an MJF Snap-Fit?

Nylon 11 is usually the safer bet when the snap has to deflect a lot. Nylon 12 stretches less before it breaks, but it can work if the deflection is modest, and it's often cheaper.

An r/AdditiveManufacturing user had a threaded cap with a 0.4 mm slit that needed to flex open and snap into place. One reply called nylon 12 a poor choice, too brittle to flex that way, and said nylon 11 would probably work depending on how far it had to flex. A PA11 print service agreed PA11 was the better material, but thought PA12 could work with some tweaking and is considerably cheaper. The first reply also suggested ordering a couple of versions with different clearances.

PA11 vs PA12 in HP's data sheets

HP publishes data sheets for both. Elongation at break is the snap-fit number, tested to ASTM D638. The HP 3D HR PA 11 data sheet lists 50% in XY and 35% in Z, and names snap fits and living hinges among its uses. The HP 3D HR PA 12 data sheet lists 20% and 15%. HP pulled the two at different test speeds, so read it as a rough comparison, not a precise ratio.

Stiffness is close: tensile modulus is 1800 MPa for PA11 and 1700 to 1800 MPa for PA12. Heat is where they split, and it depends on the load. Heat deflection, per ASTM D648, is close at 0.45 MPa: 185 °C for PA11, 175 °C for PA12. At 1.82 MPa, PA12 holds out to 95 °C in XY and 106 °C in Z, while PA11 drops to 54 °C. HP's PA12 sheet says its figures are typical values, not for specification. Still, a snap that sits loaded in a warm box favors PA12.

So which one?

Big deflection at room temperature: PA11. A clip that barely moves, or one that lives somewhere hot under load: PA12, with a longer, tapered arm to spread the strain. Prototype either way, because the arm geometry matters as much as the powder.

For arm design, read MJF snap-fits vs machined Delrin and why snap-fit tabs lose retention. Hinges flex even harder, and our living hinge post covers that material call.

What we stock

MJF Nylon 11 and MJF Nylon are both on our Materials page, and the 3D printing capability page lists "±0.3 mm or ±0.3%, whichever is greater". Not sure which one suits your snap? Ask us when you quote.