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3D Printing Ceramics


It is becoming more practical for potters and ceramic artists or entrepreneurs to take on projects never before possible because of the increasing accessibility of 3D printing of ceramic materials or of materials that can act as piece molds or block molds. Objects themselves can be printed directly by extruding layers of a ceramic paste from a nozzle and by fusing powder particles layer-by-layer. This is an additive process as opposed to subtractive (where material is cut away from a block to create a 3D object). The latter is more practical for making molds of relief designs for pressing the faces of tiles or for ramp pressing plastic clay.

The practicality of additive processes and quality and shapes that can be made are still big limiting factors to the technology. However it is clear that refractories (like shelves, posts, supports and even entire kilns) can also be printed and the smoothness of finish is not nearly as important. By printing a honeycomb structure within the refractory they can be made very light and well insulating and can be made from much more expensive materials than would otherwise be possible. Even things like stainless steel can be printed, this enables making complex molds for use with plastic and dust pressing processes.

Many technologies must be understood and exploited to make this possible in an application. One of the most difficult to surmount is learning the software design and conversion tools. This can be very confusing since hundreds of products are available. However there are standards and printers expect to receive a specific file format: STL. 3D design software can be very expensive but there are open source solutions. A major enabler has been a policy change by AutoDesk, the maker of industry standard tools for many years. They are building their future of mechanical design around Fusion 360 and, as of 2015, are releasing it for free use by education and business earning less than 100,000 per year. This product has exceptional online resources and training and this development could be the most important single factor the puts 3D into prime-time ceramic production.

Another factor is the RepRap international movement to develop open source hardware and software platforms for 3D printing. Reprap printers use standard buy-at-a-hardware-store parts or ones that the printer itself can make. This means that anyone can buy and assemble a printer to learn many details of their mechanics and operation. Once understood a printer of any size could theoretically be constructed. In ceramics the focus is on the print head and how to deliver a thick paste to it, extrude it an a constant rate and be able to turn the flow on and off in an instant. The latter can be a real challenge and one solution is to pressure-feed the paste to a print head having a barrel and auger like a pugmill and control the auger using a stepper motor to feed the actual extruder nozzle.

There is a problem with scaling to a bigger size. The printhead or platform must be able to move on at least two axes. There must be a minimum of mass resisting movement in order to have precise and quick movement. But clay is heavy and if the printhead is full of it it cannot be responsive (e.g. Delta printer designs). Likewise if the item being printed is heavy the bed on which it sits cannot move too quick (because the clay, or paste, is soft). And, lower layers of very soft clay must be able to support the entire piece, this obviously limits size. And any degree of departure from vertical side walls.

A major challenge is making the clay set fast enough so that the next layer applied over it will have a firm base. When plastics are extruded in typical home 3D printers they simply cool and firm up, but clay pastes are soft and fragile. Additions of polymers can help set them after extrusion. Augmenting the water with alcohol (e.g. ethanol is preferred over isopropyl alcohol because it carries off more water as it evaporates) speeds evaporation. Pure ethanol and clay is flammable and the plasticity and dry strength are poor. But 50:50 water:ethanol is not flammable and workability is excellent. However, even though the clay feels cold evaporation does not proceed that quickly, it needs a fan to stiffen up fast enough. Under greater pressure stiffer pastes of lower water content can be delivered. When large objects are printed, fans and the extra time between layer delivery may be enough to enable structural integrity. In some types of 3D printing, support structures of a different material are printed with the item and these are later removed, this could be practical for ceramics also.

An exciting technology is laser fusing of powder, even metal powder. In this way stainless steel can be printed. This enables printing complex molds for dust pressing of tiles.

Notwithstanding all of this, printers designed for clay are appearing on the market (with lots of excitement) and more are coming. You could easily spend $10k but use caution, the laws of physics and common sense apply. Machines have differing priorities. Those that must push clay through a thin tube to a tiny pugmill in the printhead (e.g. the Lutum and WASP machines) will obviously need soft clay and to be reloaded more often and they may not work well with deflocculated bodies (the auger having trouble getting traction). The PotterBot is moving the entire piece constantly (on the x-y axes), and when that piece gets large it becomes rather like a big cube of jello on a plate being jerked around! Obviously the body will need to be stable or it will just collapse. The only solution is often to simply print really slow. This can make the novelty of 3D printing clay wear off pretty fast! Many are shocked when they realize that even normal printing time for a large piece could be ten hours!

Don’t be stuck with a fancy machine and no clay that works with it. And, you can be sure, the manufacturers are going to follow the revenue model of ink jet printers so brace yourself when you find out the price of cartridges. It might be best to make your own bodies, that is what the pros are doing. You need a propeller mixer to blend the powder and water (more powerful mixers will do this much better). Run the mixer until all air bubbles have surfaced (to de-air it) and all particle surfaces are wetted (this could take 15 minutes). Then pour it on a plaster bat to dewater to the needed consistency. A hand extruder can be used to create the diameter needed to feed the machine (the clay needs to be soft). The character and suitability of the body will be a big part of any success you have, and understanding the recipe and being able to control it will give you a big edge (especially if you want to incorporate alcohol). Click the links below for information on a mixer and plaster table.

Clay suppliers are also producing clays for this. But be skeptical. One of the bodies claims to have 40% 80 mesh grog, however our testing found no grog! Besides, grog is undesirable since it would wear out the print head quickly. Another porcelain has 25% water yet claims to have drying shrinkage of 6.5% (this is highly improbable and even if true would make it too non-plastic and fast drying). Some have shipped in, at considerable cost, non-plastic 3D printing clays and found that the plastic bodies they have used for years work better! When printing taller objects it holds up better. When printing take a long time the bottom and top of a piece are soft and the center gets stiffer, a plastic clay that dries slower is better. In addition, printing overhangs is a big issue so plastic clays that hold up better are needed.

Because of the difficulty of preparing the clay (because it needs to be so soft, bubble-free and homogeneous) suppliers are going to introduce cartridge solutions. The advantage will be more stable & repeatable performance and a ready-to-use product with good strand adhesion and plastic strength.

To make your own body follow the same pattern. Start with and existing recipe for a plastic pottery clay (your body manufacturer may give you the generic recipe of the body you already use). Many are finding that plastic bodies are best, they stick together well, hold up and do not dry too fast. To increase plasticity of a body add bentonite (or vice versa), change kaolins to ball clays or use a more plastic kaolin. Adequate silica is needed so glazes are easy to fit (usually 20% or more). And it will need enough feldspar to make the body vitreous. For example, the popular 50:25:25 recipe for cone 10 is 50 clay, 25 feldspar and 25 silica. For cone 6 it would be closer to 45:35:20. Since it is practical to make your own paste, consider trying the Zero3 porcelain for cone 03 (it contains frit to make it vitrify).

3D Printing Polar Ice Porcelain

3D Printing Polar Ice Porcelain

By Bryan Cera.

The controller board on a common RepRap 3D printer

The controller board on a common RepRap 3D printer

This board is an "Arduino computer", a standard device around which a worldwide community of gadget-building enthusiasts has grown. It has also become standard on RepRap printers. This version has many connectors, they connect to stepper-motors (that control the X, Y, Z axis and the feeding of the filament through the printhead), to switches and sensors for the heating element and fans on the printhead and to sensors and switches for the heated bed. This board runs open source software that can read a gcode file (which defines the movements of the print head for each layer). It uses the Z-motor to move up for each new layer, the X and Y motors to control head movement for the layer and the filament-feed motor to control the extrusion.

The movable printing bed on a common 3D RepRap printer

The movable printing bed on a common 3D RepRap printer

These build-it-yourself kits are good to learn how the printers work (but don't get one until you have seen the instruction manual). The printhead slides (on bushings) along two horizontal stainless rods - the gear-belt, driven by a stepper motor on the far left, controls its left-right position along the X-Axis. Two motors on the lower left and right turn vertical worm-gears that move the printing mechanism up and down (along the Z-axis). Like the print-head, the printing bed (or platform) is pulled forward and backward by a rubber gear-belt driven by the Y-Axis stepper motor (at the lower back). The bed is heated, maintaining a temperature of about 50C, this keeps the printed piece from warping and loosening during printing. On cheaper printers like this it is common to put masking tape on the bed, pieces stick to it better. Calibrating the height of the bed is tedious on these.

The printhead of a make-it-yourself RepRap 3D printer

The printhead of a make-it-yourself RepRap 3D printer

The assembly has a powerful electric stepper-motor with attached to a gear assembly that pulls the filament in through a hole in the top. It forces the filament down through a heated nozzle. PLA is a common filament type, it requires the nozzle be at 215C to extrude well. The brass nozzle puts out a 0.45mm wide extrusion (it is mounted to the bottom of a small aluminum block at the bottom). The nozzle has a heat sensor and its own cooling fan (enabling the controller to precisely maintain nozzle temperature). An additional fan and heatsink (on the left side) keep the motor and filament feed area cool. The entire head assembly is pulled left and right along stainless steel rods by a gear-belt controlled by the X-axis motor. Inserting filament can be tricky in machines like this. The best strategy is pre-heating the nozzle, pressing release level (to enable free filament movement) and then pushing the filament to feed it manually through the nozzle, then pulling it out suddenly. To reload, cut it to a point (using scissors), configure the printer to preheat the nozzle to 215C, then feed it down through until it extrudes.

The rear of a partially assembled RepRap 3D printer

The rear of a partially assembled RepRap 3D printer

In this printer (which is being assembled) the printhead moves along two stainless steel rods (for the x-axis). Its position is controlled by the front top stepper motor (which has a gear through which runs a rubber belt attached to the printhead. The two lower stepper motors with worm gears attached to their shafts control the vertical z-axis position of the printhead assembly. Since the computer controls these motors it can move the head to any position on the x or z axis. Vertical z-movement is slower and more precise since it determines the thickness of each slice to be printed.

Hand-tooled jigger model vs. 3D-printed and cast

Hand-tooled jigger model vs. 3D-printed and cast

I am creating molds for a casting jiggering process to make mugs. I have a profile drawing I want to match (upper left). The solid model on the left is my first attempt at manual tooling. The metal template was time-consuming to make by hand, it worked poorly (the surface is rough). And the contour matches the drawing poorly. I lost the enthusiasm to even get it smooth. For the one on the right I 3D-printed a shell, poured the plaster in and then smoothed it off a bit on the wheel after the set. It matches the template and it is perfectly round (because I have a good 3D printer, a Prusa MK3S). This is revolutionary! That drawing: I hired someone on Upwork.com to draw it for me using Fusion 360. He draws things in such a way that I can fine-tune them. Then I print them using my own 3D slicer.

3D Printed mug prototype

3D Printed mug prototype

Although made on an inexpensive Reprap printer it is fine for visualizing the size and shape. An important first step in designing a mug for production to a commercial client.

Here is what happens when an overnight 3D print goes wrong

Here is what happens when an overnight 3D print goes wrong

From Brooks Talley. At some point during the night the base could not support the layers being added and it collapsed. The printer happily just kept printing in mid air for the rest of the night!

3D Printing the Medalta 66 prototype mug

Show on Post Page

This took 12 hours! Notice the supports it prints for the handle. These break away after it is done. Of course the surface is not smooth enough to use as a model, but the purpose was to hold it to judge size, wall thickness, handle feel and shape. I will make the molds and jigger templates using the printer also.

Printing a prototype propeller for my Lightnin lab mixer

Printing a prototype propeller for my Lightnin lab mixer

An example of how handy the ability to print in 3D can be. The worn-out stainless propeller costs $300 to replace. But the size and pitch of the blades is not right anyway. So I draw them using Fusion 360 and print them in PLA plastic, enabling experimenting with different sizes and pitches. While I could have one printed in stainless at shapeways.com I do not need to because these plastic ones are surprisingly durable. How about getting a tight fit on the shaft? No problem. I measured this shaft with a callipers and printed that size. It was a little tight so I printed slightly larger and it fits very tightly. One issue: If you mix slurries with hot water, it will travel up the shaft and the blades will bend.

Making ceramic tile shapes by 3D printing your own cookie cutters

Making ceramic tile shapes by 3D printing your own cookie cutters

This was done on an affordable RepRap printer. The red plastic templates were drawn in Illustrator, extruded in Fusion 360 and sliced and printed using Simplify3D (which took about 30 minutes each). The round wooden block was used to press these cookie-cutters into the clay. The plastic wrap made sticking a non issue (and rounds the corners nicely). The clay is a low fire, buff burning talc body (Plainsman L212). Commercial bottled glazes were applied by brushing (in three coats) after bisque. The tiles were fired at cone 03. This is an old classic design that I discovered when researching Damascus tile. The toughest obstacle was learning how to use Fusion 360. It turns out that cookie cutters are a starter project for many 3D software packages, there are lots of videos on making them.

Out Bound Links

In Bound Links

  • (Glossary) 3D Slicer

    Slicing software converts a 3D model (drawn by Fusion 360 or other 3D designer) into G-Code that a printer can understand. The G-Code contains head movement and temperature instructions. Many free and paid products are available. They can exist because of standards developed over the years in the 3D...

  • (Articles) A One-speed Lab or Studio Slurry Mixer

By Tony Hansen




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