www.3ders.org

Mar 21, 2019

We recently wrote about several projects that aim to increase the strength of 3D printed components. In November 2018, the "Father of RepRap," Dr. Adrian Bowyer, demonstrated how hollow tubes could make 3D prints stronger. Later, Stefan Hermann at CNC Kitchen experimented with Smart Infill for stronger 3D prints.

After 10 years of experimentation, Kai Parthy, inventor and developer of smart filaments (lay-filaments), has now developed a method that could locally strengthen FFF 3D printed components with little material effort. The method results in the adhesion between layers being immensely increased; moreover, the strength of the entire object can be optimized locally.

"Stratasys invented the FDM 3D printer, but the task to increase the strength in Z-axis direction has been challenging since then. So this could be a solution," stated a Stratasys manager.

The solution is the use of reinforcing elements, or "z-anchors," which can avoid layer cracks, save weight, optimize the local static within the object, and reduce the wall thickness.

Likewise, functional fillers can be poured into the object (for example, those that conduct electricity).

The process is shown schematically below:

Layered object (A) is not very stable and can (B) break along the along the layers when forces (F) act. When printed with z-anchors (C), the object is more stable as these hold the object together in the direction of the z-axis.

The same principle is applied for SLS-sintered or binder-jet objects.

How are z-anchors made?

There are two methods:

1. z-anchors made of filament can be filled into the cavity during the normal 3D printing process. For this purpose, the filament is heated more so that it flows smoothly into the space and cools. These cavity shapes may not be as complex as those filled with resin. Conceivably, of course, a printer can be equipped with up to three filaments, with a special filament for the z-anchors that has the required flow properties.

2. z-anchors made from a two-part resin are completely free in design. Any shape is possible—slim, stretched with geometric subtleties—as resin is injected into the cavity using fine-dispensing pumps.

How do the cavities for the z-anchors get into the object?

These can be placed in the object by the designer. This makes sense especially if there are special stiffness requirements.

During slicing, the software calculates the cavity space. The software performs strength calculations to achieve high strength while using less material.

z-Anchors can be also be filled with steel or fiber-reinforced plastic rods prior to resin injection for even greater strength.

The cavities also can be filled with materials that are particularly stable (high tensile strength). It is also conceivable, of course, that they can be filled with an electrically conductive resin.

We asked Kai about the progress of the project. "At the moment, I am looking for industrial partners or research institutes for the realization with my long-time colleague Bernd Hackemann, who has developed a basic special cleaning agent (3Dwash) for alkali-soluble support filaments," Kai told us. "I am thinking of partners from the FDM printer industry, sinter printer manufacturers (SLS), software companies offering slicing apps or manufacturers of special dosing pumps. Also, intellectual property rights for the idea are registered."

Interested parties can contact Kai Parthy via email kp@cc-products.de.

Posted in 3D Printing Technology

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Peter wrote at 4/1/2019 6:41:25 PM:

Kai, No idea. Seems like a great idea. Since it's owned by Makerbot, maybe they or Stratasys are planning on implementing it? More likely, they'll do nothing with it. Patents look good to shareholders, even when you're not making use of them.

Kai wrote at 3/29/2019 11:18:41 PM:

Peter, what do you think, why did the two patents you mentioned not succeed? Why have not they been implemented anywhere?

Peter wrote at 3/28/2019 1:40:21 AM:

See: US Patent 9475233

Peter wrote at 3/28/2019 1:35:35 AM:

See: US Patent 9475233

Colin wrote at 3/26/2019 7:21:44 PM:

See: US Patent Application Publication US20180311891 A1

Michael wrote at 3/23/2019 7:05:11 PM:

I've been doing something like this for polypropylene, hdpe by programming overextruded z hops into the slicer. By leaving a hole 1/4-1/2 the filament width and programming my slicer to skip over holes the printer will create small spires at various places which are smashed down and bonded to the next layer. It's not as strong as steel but works on most fdm consumer printers

Greg Fischvogt wrote at 3/23/2019 1:34:30 PM:

A simple fix that I’ve used when my prints were shearing at a stress concentration was to print the part at a slight angle, say 15 degrees. What happens is you no longer have the bond between a single pair of layers take all the load. Instead you could have the load spread over a few to many layers depending on the angle chosen and the length of the shear joint in question. To do this, align the part in slicer as you would do normally to center on the build plate and the rotate the part about one axis the desired number of degrees. Experiment with the amount. See how the angle compromises other features or changes the amount of support needed. Nice thing is this is something you can try today. No new technology needed.

William Pealer wrote at 3/22/2019 2:12:54 PM:

why is this just a speculative article? this is very doable and try-able. I am am speculative because this is so easy to try and test, yet the article has no actual trials. Everyone knows Z shear is a boundry originating problem. If you were going to add strength or resistance to Z sheer, focusing on walls and inner walls would be priority.

Brian wrote at 3/22/2019 11:22:50 AM:

A distinct type of infill could be designed to create the necessary voids. Would be interested in seeing this. Maybe a sub-perimeter would be useful in creating a sort of roto-molded effect with epoxy between the visible outside perimeter and the inside sub-perimeter.

I.Am.Magic wrote at 3/22/2019 8:38:28 AM:

I remember seeing this at Rapid and TCT 2018 by some researchers, sorry can't find their presentation.

Marcin Chilik wrote at 3/22/2019 6:27:30 AM:

What about using graphene and anchor?

Tim wrote at 3/21/2019 6:52:51 PM:

What a fantastic idea... this could easily be implemented in a slicer, even just using regular filament. Leave a vertical shaft open for some number of layers, then just pause'n'pour.

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