Multi Jet Fusion (MJF) 3D Printing: Complete Guide
How MJF works, how it compares to other methods, and when to use it for the best results in functional prototypes and low-volume production.
Read the ArticlePP 3D Printing Material
Multi Jet Fusion (MJF) · Engineering Plastics
Lightweight, chemically resistant polypropylene with great fatigue life.
What Is PP?
MJF Polypropylene is a lightweight, chemically resistant material with excellent fatigue resistance and very low moisture absorption. It is well suited to living hinges, watertight enclosures, fluid components, and parts that must endure repeated flexing or chemical contact.
Polypropylene - Multi Jet Fusion, printed with Multi Jet Fusion (MJF). Every order is reviewed by our engineering team - no minimum order quantity.
When to choose PP
Choose MJF PP when your part needs chemical resistance, low moisture absorption, or the fatigue life to survive tens of thousands of hinge cycles. PP is the classic living-hinge material - the same property that makes injection-molded PP bottle caps work translates directly to printed PP. It also absorbs essentially zero moisture, making it ideal for fluid-handling parts, chemical containers, and any application where dimensional stability in wet or humid environments matters.
PP is weaker and less stiff than PA12 (30 MPa tensile vs 48 MPa), so if your part needs structural strength, PA12 is the better nylon. PP is also lighter (0.90 g/cm³ vs 1.01 g/cm³), which matters for weight-sensitive applications.
One critical trade-off: PP has very low surface energy, making it difficult to bond with adhesives, paint, or coat. If your assembly requires gluing, PA12 or PA11 accept adhesives much more readily. For parts that must be chemically inert and light, PP is the right call.
Material Properties
Representative values - process- and orientation-dependent. Full technical datasheet available on request.
Process
Multi Jet Fusion (MJF)
Tensile strength
30 MPa
Elongation at break
20–30%
Flexural modulus
1,300–1,500 MPa
Heat deflection (HDT)
100 °C @ 0.45 MPa
Density
0.90 g/cm³
Max build size
≈ 380 × 285 × 380 mm
Min wall thickness
1.0 mm
Resolution / layer
≈ 100 µm
Relative cost
$$ (1 = lowest, 4 = highest)
Design Guidelines
Plan features to print reliably and assemble cleanly in PP. Need DFM help?
Min wall
1.0 mm - 1.5 mm+ for watertight
Min feature
0.5 mm - fine detail limit
Living hinge
0.4–0.6 mm - thin web at hinge
Drainage
≥ 2 mm holes - for hollow sections
Dimensional tolerances
Typical tolerance is ±0.3 mm or ±0.3%. PP can exhibit slightly more warpage than PA12 on large flat parts due to crystallization during cooling. Uniform wall thickness is important. For living-hinge features, orient the hinge web in the XY plane. Post-machining is available but note that PP's flexibility makes fixturing more challenging - clamp carefully to avoid deformation.
Printing notes
MJF PP parts are produced on HP Multi Jet Fusion systems. The process uses the same MJF method as PA12 but with polypropylene powder. PP has lower density than nylon (0.90 g/cm³), producing the lightest parts in our powder-bed catalog. The powder bed self-supports all geometry. PP has very low moisture absorption (< 0.1%), so drying is less critical than for nylon, but storage in controlled-humidity environments is still standard practice. Parts emerge in a white/gray color. Cooling cycles are managed to control crystallization behavior, which affects dimensional accuracy and mechanical properties.
How PP Compares
PP alongside related materials.
| PP | PA12 (MJF) | PA11 (SLS) | TPU 95A | |
|---|---|---|---|---|
| Tensile strength | 30 MPa | 48 MPa | 47 MPa | 27.3 ± 0.8 MPa |
| Heat deflection (HDT) | 100 °C @ 0.45 MPa | 175 °C @ 0.45 MPa | 157 °C @ 0.45 MPa | - |
| Flexural modulus | 1,300–1,500 MPa | 1,730 MPa | ≈ 1,100 MPa | Low–medium (elastomer) |
| Elongation | 20–30% | 15–20% | 40–50% | 250–350% |
| Density | 0.90 g/cm³ | 1.01 g/cm³ | 1.02 g/cm³ | 1.22 g/cm³ |
| Relative cost | $$ | $$ | $$$ | $$ |
When to Use PP
Where PP fits, where it doesn't, and what to use instead.
Living-hinge assemblies
PP's fatigue resistance lets 0.4–0.6 mm hinge webs survive 10,000+ flex cycles - the same property that makes injection-molded PP bottle caps work, now available in printed parts.
Consumer ProductsWatertight enclosures and fluid tanks
Moisture absorption under 0.1% keeps dimensions stable in wet and submerged environments where nylon absorbs 0.5–1.5% and swells out of tolerance.
EngineeringChemical-handling manifolds and fittings
Resists most acids, bases, alcohols, and aqueous solutions - viable for laboratory fluid routing, agricultural chemical dispensing, and industrial rinse systems.
EnergyLightweight sensor and IoT housings
Lightest powder-bed material at 0.90 g/cm³ (11% lighter than PA12) - matters in drone payloads, wearable enclosures, and battery-weight-constrained designs.
RoboticsMedical and laboratory fluid components
Low moisture absorption and broad chemical inertness make PP suitable for single-use and short-term fluid-path prototypes in regulated environments.
Medical DevicesStrengths
- Best fatigue life in the catalog for living hinges - thin webs survive 10,000+ cycles where PA12 and PA11 begin fatiguing at 1,000–2,000
- Near-zero moisture absorption (<0.1%) vs nylon's 0.5–1.5% - dimensions stay locked in humid, wet, or submerged environments
- Lightest material in the powder-bed catalog at 0.90 g/cm³ - 11% lighter than PA12 for weight-sensitive applications
Keep in mind
- 30 MPa tensile and 1,300–1,500 MPa flex modulus - weaker and less stiff than PA12 (48 MPa, 1,730 MPa); do not substitute for nylon in structural-load applications
- Very low surface energy makes adhesive bonding unreliable - design for snap-fit, mechanical fasteners, or ultrasonic welding instead of gluing
- PP crystallization during cooling can cause warpage on large flat parts - keep wall thickness uniform and discuss geometry with us at DFM review
Finishes & Colors
Finishing options and in-stock colors for PP.
Standard
De-powdered, matte gray finish.
Best for: Functional & fluid parts
In-Stock Colors
Gray / White
Custom colors and dyeing available on request. Contact us for options.
PP FAQ
Polypropylene's low moisture absorption and chemical resistance make it a strong choice for watertight and fluid-handling parts. Design adequate wall thickness - we'll review your geometry at quote.
PP has excellent fatigue resistance, so thin hinge webs can flex many thousands of cycles without failing - a classic use for the material.
PA12 is stronger (48 MPa vs 30 MPa) and stiffer (1,730 MPa vs 1,300 MPa). PP is lighter (0.90 vs 1.01 g/cm³), more chemically resistant, absorbs less moisture, and has better fatigue life for hinges. Choose PA12 for structural parts; PP for chemical resistance, hinges, and fluid handling.
PP is notoriously difficult to bond due to its low surface energy. Standard adhesives do not adhere well. Specialized PP adhesives, mechanical fasteners, or snap-fit designs are recommended for assembly. If bonding is critical, PA12 accepts adhesives much more readily.
Polypropylene is widely used in food-contact applications in injection molding. Printed PP may have different surface characteristics. Discuss food-contact requirements at quote and we will confirm suitability for your specific application.
PP resists most acids, bases, alcohols, and aqueous solutions. It is not resistant to chlorinated solvents, aromatic hydrocarbons, or strong oxidizing agents. For specific chemical compatibility, contact us with your chemical environment details.
We hold ±0.3 mm or ±0.3%. PP can warp slightly more than PA12 on large flat parts due to crystallization behavior. Design uniform wall thickness and discuss geometry with us at quote for best results.
MJF PP is at the $$ cost tier - comparable to MJF PA12. It is cost-effective for runs of 20–2,000 parts. For applications requiring PP's specific properties (chemical resistance, fatigue, low moisture), there is no cheaper alternative in our 3D printing catalog.
Technical Documents
Related Articles
How to Choose the Right MJF Materials for Functional Prototypes and Production Parts
Many failures come from excessive deflection, creep, or cracking rather than lack of strength. Understanding PA12, PA11, glass-bead PA12, TPU, and FR grades.
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