3-D Printing with Metal

[MrRiedemanJACC]

I teach Project Lead the Way at the Jackson Area Career Center and we are now in the Engineering Design and Development class. For those of you not aware of this class it is the capstone project for my students. I have one team that is working on developing an affordable metal 3-D printer. They are at the point in the project where they are looking for customer data to help drive the design. If you could, please take a few moments to take the attached survey and leave comments also. Thank you soo much for your time.

https://docs.google.com/forms/d/1_j-...?usp=send_form


John Riedeman
IED, POE, DE, and EDD PLTW Instructor at the Jackson Area Career Center
Team 2611 Jacktown Vectors Mentor

[techhelpbb]

There are some typos in the survey: write not wright.
Also is this a laser sintering printer design?

[MrBasse]

How do they plan to extrude metal? Especially iron or ferrous metals? Even aluminum would take an impressive heating element and then would result in a puddle of metal rather than a controlled plastic flow of material.

Or is the plan just to deposit controlled amounts of material in a small area and build up layer thickness based on the thickness of metal flake? Essentially making a thin layer metal laminate? I'm curious as to their solution for this, and am interested in how you are testing results.

[Sperkowsky]

Originally Posted by MrBasse

How do they plan to extrude metal? Especially iron or ferrous metals? Even aluminum would take an impressive heating element and then would result in a puddle of metal rather than a controlled plastic flow of material.

Or is the plan just to deposit controlled amounts of material in a small area and build up layer thickness based on the thickness of metal flake? Essentially making a thin layer metal laminate? I'm curious as to their solution for this, and am interested in how you are testing results.

I believe all metal 3d printers use a mix of plastic and metal in them. I also know some do metal coated items. Ill see a bit more of the trend in a little over a month at the 3d printing expo.

[BeardyMentor]

Originally Posted by Sperkowsky

I believe all metal 3d printers use a mix of plastic and metal in them. I also know some do metal coated items. Ill see a bit more of the trend in a little over a month at the 3d printing expo.

Incorrect, There are a few types commonly used. The most common is Direct Metal Laser Sintering. This uses a laser to melt metal powder, then spreads a new layer of powder and so on. Next there is Electron Beam Melting. This preheats a metal powder bed to near the melting point then uses an electron beam to melt the powder. Next is the ExOne process that uses a binder to glue metal powder together, then the parts are infused with bronze in a furnace. There are also selective deposition printers using lasers or electric arcs to melt metal as it is deposited in a similar way to the desktop printers you are likely familiar with. There are also printers that extrude a metal clay. There are some others but this covers 99% of what is out there right now.

When you go to the 3D printing Expo, check out EOS, they usually have an M280 on display. Also Arcam and Renishaw are usually there with some of their printed products.

[Chris_Ely]

John,
This might be of interest to your students as they continue their design:
Scientists Build a Low-Cost, Open-Source 3D Metal Printer

I submitted the survey. I am very interested in what your students come up with.

[techhelpbb]

3D printing (really material addition) with a MIG/GMAW welder is not actually a new idea.
The issue with those welders is the spatter and properly slicing the model to insure the welds laid down are consistent over the travels.

You can't really do like a 3D plastic extruder does. A 3D plastic extruder is basically pushing into a state of partial stall on the extruder stepper. That's part of the reason the extruder steppers tend to get hot. Once we get an arc going the spool in a MIG does not take much effort to push too much and takes some skill not to push too little.

So while I can see putting a MIG torch suitable for CNC operation on a Prusa I3 frame in the same way I can so doing it with a CNC plasma cutter. What I don't see is how you control the quality of the weld consistently over different objects. With a plasma cutter the goal is really to cut and sever so as long as you are in the ball park it's good enough considering what it's doing.

To put this in perspective we've had robotic arms do MIG/GMAW for decades now.
There's a process to dial them in to achieve the right results on a consistent flow of similar parts that start at room temperature.
In trying that with 3D printing you are laying down metal that will cool and the size and shape of the target will change as you reheat the welds changing various aspects as the thermal mass changes.

http://hackaday.com/2014/11/07/print...-a-mig-welder/

So in the video they make a simple 'wall'.

Didn't really need a Prusa printer frame for this purpose.
A cheap school robotic arm could manage the same with basic motion control it just wouldn't be Cartesian.
So maybe you start the travel and you exit after the straight line to let it cool or force air to cool it.

However if you look the layers are more inconsistent than 3D plastic printing.
So the 'slicing' or making of layers would become much more difficult for complex layer travels.

I wouldn't aspire to making plates of metal as a 3D printing goal.
At that point I'd rather have a robotic arm welder to weld properly prepared plates for more consistent results.
Maybe more robotic arms to grasp the assembly in progress of assembly.
The inverse kinematics of the robot arm welder and work holders are equally an interesting motion control problem.
That's a problem where the feedback of actually maneuvering the arms manually could be really helpful in training the robot.

[asid61]

Best of luck! I would like to see something that's not a welder, as my school banned us from having one on the grounds that it was "unsafe".
Meanwhile, the milling machine, bandsaw, and various power tools are A-OK.

[JesseK]

Originally Posted by asid61

Best of luck! I would like to see something that's not a welder, as my school banned us from having one on the grounds that it was "unsafe".
Meanwhile, the milling machine, bandsaw, and various power tools are A-OK.

Welding requires proper ventilation as the aluminum additives heat and off-gas. I don't know your shop, but welding is considered unsafe without the ventilation.

In other news, metal 3D printing is so last year:
http://arstechnica.com/science/2015/...tead-of-hours/