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What is MJF (HP’s Multi Jet Fusion) 3D Printing?
MJF is a big way to make things. It is HP’s way to print 3D parts. MJF is fast and good. It can make parts that are strong. It is not like old ways to make things. HP made this new way to print things in 3D.
Table of Contents
How Does MJF 3D Printing Work?
MJF works in steps:
- Powder Bed: A thin layer of PA 12 nylon powder is put down. It is very thin!
- Agent Drops: Ink jets put down tiny drops on the powder.
- Heat Lamps: Big hot lamps make the powder melt where the drops are.
- New Layer: More powder gets put down on top.
- Clean Up: When done, the part comes out of the powder bed.
The part is made in the powder. The powder that does not melt can be used again! This makes less waste.
MJF vs. Other 3D Printing Ways
| What We Look At | MJF | SLS | FDM |
|---|---|---|---|
| Speed | Very Fast – 4-6x more than others | Just OK | Slow |
| How Good It Is | Very good (±0.3%) | OK (±0.5%) | Not as good (±0.5%+) |
| How It Looks | Smooth with help | Grainy | Can see lines |
| What It Can Use | PA 12, PA 11, TPU | Nylon, some more | PLA, ABS |
| Best For | Parts you will use | Test parts | Low cost tests |
MJF is fast. It is 4 to 6 times faster than old ways. The parts look good with some help. MJF is best for real parts you will use.
Key Uses of MJF 3D Printing
MJF is good for many jobs:
- Cars: Parts that go in cars need to be strong. MJF can make them!
- Air Planes: Parts that need to be light but strong.
- Body Parts: Like new legs for people who need them.
- Jobs in shops: Like CNC Würfel who made gripper parts way faster with MJF.
A shop called CNC Würfel had a big win with MJF. They made a gripper adapter part. The old way took 8-10 weeks. With MJF, it took just 5 days! They saved 40% costs too.
Good Things About MJF
MJF has lots of good things:
- Fast: It can make a full box of parts in less than 24 hours.
- Low Cost: When you make lots of parts, each one costs less.
- Strong: The parts are strong all the way through.
- Less Waste: You can use 80% of the powder again.
HP and BMW made car parts with MJF. They had big wins. The parts cost 60% less than old ways. That is a lot of money saved!
MJF Has Some Hard Parts Too
MJF is not all good. It has some hard parts:
- Not as many materials as other ways
- Big machines cost a lot (HP 5200/5400 kinds)
- Parts need some work to look their best
If you need just one test part, MJF might cost too much. But if you need lots of parts, MJF can save you money.
When Should You Use MJF?
Use MJF when:
- You need parts with hard shapes
- You need 100 to 10,000 parts
- You need parts that work well
Do not use MJF when:
- You need just one test
- Your part gets very, very hot (over 180°C)
HP MJF Machines and What They Use
HP makes a few kinds of MJF machines:
- HP Jet Fusion 5200: For shops just starting
- HP Jet Fusion 5400: For more work
- HP Jet Fusion 5600: For big shops with lots of work
MJF uses these materials:
- PA 12: Most used – good and strong
- PA 11: More bend to it
- TPU: Like a soft rubber
- BASF Ultramid®: For very tough parts
One test found PA 12 parts made with MJF had a strength of 48 MPa. That’s as strong as parts made other ways!
Big Questions People Ask
Q: Is MJF stronger than SLS?
Yes! MJF makes more dense parts.
Q: Can MJF parts replace injection molding?
Yes, if you need less than 10,000 parts.
Q: How big can MJF parts be?
380 x 284 x 380 mm on HP 5200 machines.
MJF 3D Printing vs. Injection Molding
| What We Look At | MJF | SLS | Injection Molding |
|---|---|---|---|
| How Long It Takes | 2-5 days | 1-2 weeks | 6-12 weeks (need tools) |
| Cost (100 parts) | $10 each | $15 each | $2 each (after $10k for tools) |
| How Thin Walls Can Be | 0.5 mm | 1.0 mm | 0.8 mm |
| How It Looks | Needs work | Rough | Smooth |
MJF is fast for when you need parts soon. Injection molding is better when you need lots and lots of parts – like more than 10,000!
Which Way Is Best?
One shop looked at many ways to make parts. They found:
- MJF is 30-50% cheaper than SLS for 100 to 10,000 parts.
- MJF parts are more strong and dense.
- Car and body part makers like MJF the most.
MJF is best when:
- You need complex shapes
- You need parts fast
- You need 100 to 10,000 parts
If you need just one test part, maybe use 3D CNC machining or a more low-cost way. If you need more than 10,000 parts, look at die machining for tools.
MJF Makes Better Parts
When MJF first came out, tests found it was a big step up:
- Parts from MJF had less thin spots
- Parts were more strong all the way through
- Parts fit well with other parts
This is why shops like car makers and medical CNC machining shops use MJF now.
The Big Wins with MJF
Let’s sum up why MJF is so good:
- Fast – Makes parts in hours not days
- Strong – Parts work as well as other ways
- Good Value – Saves money when you need 100+ parts
- Less Waste – Uses most of the powder again
MJF helps make the jump from just test parts to real parts you can use. No need to wait for tools to be made!
