MJF TPA is a flexible, rubber-like material for HP Multi Jet Fusion. Incremental-AM prints it in HP 3D High Reusability TPA, enabled by Evonik, on our HP Jet Fusion 4200. It is a thermoplastic elastomer with a hardness of around 91 Shore A, high rebound and good performance at low temperatures, so it suits parts that need to bend, cushion, seal or absorb impact.
Why choose TPA?
- Flexible and tough: elongation at break of around 250% (XY), so parts stretch and recover rather than crack.
- High rebound: 72% rebound resilience. HP rates its energy return above the other MJF TPU materials, which makes it very good for impacts.
- Works in the cold: better mechanical resistance at low temperature than the other MJF TPUs.
- Light: a density of about 1.0 g/cm³, lighter than the other MJF elastomers.
- Tunable with lattices: change the lattice and you change how soft, stiff or springy the part feels, all in one material and one print.
- Good looking parts: good detail, even colour, and a pleasant look and feel on visible surfaces.
Typical applications
- Cushioning, padding and protective inserts
- Shock and vibration absorbers, bump stops and buffers
- Seals, gaskets, bellows and boots
- Grips, handles and soft-touch covers
- Flexible clips, hinges and cable management
- Lattice parts for sports and protective equipment
Material properties
Typical values from HP for HP 3D HR TPA enabled by Evonik on the HP Jet Fusion 4200 (Balanced print profile, natural cooling, bead blasted).
| Property | XY | Z | Test method |
|---|---|---|---|
| Hardness | 91 Shore A | 91 Shore A | ASTM D2240 |
| Tensile strength | 10 MPa | 8 MPa | DIN 53504 / ISO 37 |
| Tensile modulus | 75 MPa | 80 MPa | DIN 53504 / ISO 37 |
| Elongation at break | 250% | 120% | DIN 53504 / ISO 37 |
| Tear strength | 50 kN/m | 40 kN/m | ASTM D624 |
| Rebound resilience | 72% | 72% | ASTM D7121 |
| Compression set | 40% | 40% | DIN ISO 815 |
| Density | 1.0 g/cm³ | ASTM D792 | |
Typical values only, not guaranteed minimums. Results vary with geometry and orientation. HP quotes typical tensile strength of 8–11 MPa and tensile modulus of 55–100 MPa.
Design guidelines for MJF TPA
| Feature | Recommendation |
|---|---|
| Maximum part size | 380 × 284 × 380 mm |
| Wall thickness | 1.0 mm minimum, 2.0 mm recommended, 7.0 mm maximum (walls under 0.8 mm may not print) |
| Minimum clearance | 0.5 mm (at 1 mm thickness) |
| Minimum slot between walls | 0.75 mm |
| Minimum hole diameter | 1.0 mm (at 1 mm thickness) |
| Minimum shaft diameter | 1.0 mm (at 10 mm length) |
| Text and logos | 12 pt minimum (4.2 mm high), 1 mm emboss or deboss |
| Hollow parts | At least two 10 mm drain holes on opposite faces |
| Lattices | 5 mm minimum clearance between cells. A good starting point is an 8 mm cell with 1.2 mm struts (no thinner than 1.0 mm) |
| Lattice skins | 1.0 mm minimum shell thickness, with struts joined firmly to the shell |
| Layer thickness | 100 microns. Keep important curved or sloping surfaces above 30° to the horizontal to reduce stair-stepping |
Not sure your design is right for TPA? Send us the file and we'll tell you honestly. Our design advice is free.
TPA or PA12?
Choose MJF PA12 for rigid, strong parts such as brackets, housings, jigs and fixtures. Choose TPA when the part needs to flex, cushion, grip or seal. The two are often used together, for example a PA12 housing with a TPA seal or bumper.
Finishing
Straight from the printer, TPA parts are bead blasted and a mid grey with a slightly grainy surface. We recommend black dyeing and vapour polishing for TPA. Together they give a deep, even black and a smoother, sealed surface that looks and feels much more like a moulded rubber part. See our finishing options.
Compliance and limitations
- Non-hazardous under GHS / EU CLP, and not classed as dangerous goods for transport.
- Printed parts have been tested by HP for RoHS restricted substances, and none were detected.
- Not suitable for food contact.
- Not suitable for medical devices or prolonged skin contact. The material did not pass ISO 10993 cytotoxicity testing.
Frequently asked questions
How flexible is MJF TPA?
At around 91 Shore A it feels like a firm rubber, similar to a shoe sole or a skateboard wheel. Thin walls and lattices make parts much softer, so you can tune the feel through the design.
Is TPA the same as TPU?
Both are thermoplastic elastomers. HP 3D HR TPA (a polyether block amide based material from Evonik) has higher rebound, better low-temperature performance and a lower density than the TPU materials available for MJF.
What colour are TPA parts?
Mid grey as printed, with a slightly grainy surface. Most customers choose our recommended black dye and vapour polish for an even black, smooth finish.
How do I get a quote?
Upload a STEP or STL file to our instant quote, choose TPA and your finish, and order online. For batch production or design help, contact us or call 01256 533838.
Downloads
- HP design guidelines for HP 3D HR TPA enabled by Evonik (PDF)
- HP Jet Fusion 4200 materials: mechanical properties white paper (PDF)
- HP 3D HR TPA regulatory compliance and environmental summary (PDF)
Documents published by HP Inc. and supplied by Incremental-AM. HP data is typical and may change without notice.