Learn · HP Multi Jet Fusion
Vapor smoothing for HP Multi Jet Fusion parts.
MJF vapor smoothing turns the gray, grainy, porous surface of an HP Multi Jet Fusion part into a smoother, sealed skin in one automated cycle. PostPro systems vapor smooth MJF parts in PA12, PA11, TPU and polypropylene, with the finishing agent chosen by material.1
No cost to evaluate · Parts returned · Typical turnaround 2–3 weeks2
Why MJF parts need finishing
Strong parts, with a printed skin.
MJF prints strong, accurate nylon and elastomer parts at volume. They come out of the build gray, slightly grainy and porous, which shows on any part that is touched, worn, washed or sold.
Porous surface
Partly fused grains leave pores that take up water, sweat, dirt and dye unevenly.
Gray and grainy
As-printed parts look printed. Vapor-smoothed MJF parts come out darker and more polished.5
Hygiene
Medical, food and wearable parts need a surface that cleans. Sealed finishes keep out sweat and bacteria.5
Production volume
MJF prints full builds of parts at a time; finishing has to keep up without a person per part.
Published results
What vapor smoothing measured on MJF parts.
Each result names the material it was measured on. Results depend on material, printer and recipe.
Surface
13.42 → 1.18 µm32022
Surface roughness, as printed to vapor smoothed BASF Ultrasint TPU01 · HP MJF
Surface
Reduced surface porosity on UL94 V-0 flame-retardant parts6
Protolabs case study HP 3D HR PA 12 FR · HP MJF
Skin contact
No cytotoxic effects and no loss of strength4
Cytotoxicity test HP 3D HR PA 12 · HP MJF · PostPro Pure
MJF with PostPro Pure whitepaper HP PA12 finishing whitepaper
Workflow
From build unit to finished part.
Vapor smoothing slots in after cleaning and before dyeing or inspection. The vapor needs to reach the part’s real surface, so loose powder comes off first.
Print and cool
The build cools in its unit before parts come out.
Clean off powder
Loose, unfused powder is removed so the part’s surface is exposed.
Vapor smooth
Parts hang on a rack in the PostPro chamber for one automated cycle: 1.5–2 h7 on the SF50 and SF100.
Dye, inspect, ship
Color if needed, check, and the part is ready for use.
| Material | PostPro Pure | FA326 | FA9202 |
|---|---|---|---|
| PA 121 | Listed | Listed | Not listed |
| PA 12 Filled1 | Listed | Listed | Not listed |
| PA 111 | Listed | Listed | Not listed |
| Forward AM TPU1 | Listed | Listed | Not listed |
| Lubrizol TPU1 | Listed | Not listed | Not listed |
| Polypropylene1 | Not listed | Not listed | Listed |
Listed by AMT— Not listedPostPro Pure runs in every PostPro system; FA326 on the SF50 and SF100; FA9202 for polypropylene.
In production
MJF parts in service.
Published case studies on vapor-smoothed MJF parts, each linked to the full story.
GMUltrasint TPU01
Spoiler closeout seals
60,000 parts, needed quickly to avoid delaying 30,000 vehicles82023
ProtolabsPA12 FR
Flame-retardant parts
Flame-retardant parts with improved surface quality and UL94 V-0 compliance6
Point DesignsPostPro SFX
Partial hand prostheses
Smooth, sealed surfaces that improve comfort and hygiene9
Which PostPro
Which PostPro for your MJF fleet.
Desktop systems for R&D and small batches, production systems for full builds. Every PostPro system lists PA12, PA11 and TPU.7
Questions
MJF vapor smoothing: questions.
Short answers from AMT’s published tests and material lists. Anything else, ask an engineer.
Can you vapor smooth MJF parts?
Yes. PostPro systems vapor smooth HP Multi Jet Fusion parts in PA12, PA11, TPU and polypropylene, with the finishing agent chosen by material.1
Does vapor smoothing work on HP 3D HR PA 12?
Yes. In AMT’s test of HP 3D HR PA 12 printed by MJF and finished with PostPro Pure, the result was No cytotoxic effects and no loss of strength4.
Do MJF parts need cleaning before vapor smoothing?
Yes. Loose powder is removed first, so the vapor reaches the part’s real surface and finishes it evenly.
Can vapor-smoothed MJF parts be dyed?
Yes. Dyeing and vapor smoothing are often combined, and vapor smoothing alone already darkens an MJF part. Ask AMT which order suits your material.
Which PostPro suits an MJF fleet?
All four systems list PA12, PA11 and TPU. The SFX and SF2X suit R&D and small batches; the SF50 and SF100 take production volumes. The configurator helps you size it.
Next step
See the price. Run the numbers. Hold the part.
List prices are public and the cost-per-part math is yours to check, with no email needed for either. The free benchmark puts your own parts, vapor smoothed, in your hands.
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01Quote
Build your quote
Pick a system and its options and get an itemized total on screen, from AMT’s published list prices.
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02ROI
Calculate your ROI
Compare your cost per part with manual finishing, using your own labor rate and volumes. Every assumption is editable.
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03Benchmark
Test your parts, free
Ship us your parts with a prepaid label. We vapor smooth them and send them back with before-and-after photos and a benchmark report.
No cost to evaluate · Parts returned · Typical turnaround 2–3 weeks2
Prices: AMT list prices, excluding tax and shipping; confirmed in your formal quote.
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