Thermwood tests 3D printed carbon fibre-filled PPS panels without coatings

Thermwood has taken a major step toward its goal of 3D printing autoclave capable tooling from high temperature carbon fibre filled thermoplastic materials.

The manufacturing company 3D printed 50% carbon fibre-filled PPS panels on its LSAM additive manufacturing machine, maintaining the part’s vacuum to an industry-standard level, without coatings. Testing of the part was conducted by the Fleet Readiness Center, located at MCAS Cherry Point, NC, under a previously announced Cooperative Research and Development Agreement (CRADA) partnership. The results met FRC-East acceptance criterion that the bag must not lose than more than 2 in Hg over five minutes.

As an added benefit, Thermwood believes it will soon be capable of producing moulds and tooling that function properly under vacuum in a heated, pressurized autoclave, also without the use of any type of coating to seal the printed tools.

Previously, other unaffiliated companies have tested actual tools printed by Thermwood from 20% Carbon Fibre-filled ABS and have also found that those tools held vacuum to an acceptable level without the use of any sealer or coating; however, the ABS material is not suitable for high temperature applications.

Yet, several parts have been made from those tools under vacuum at room temperature and at slightly elevated temperatures. Thermwood has also already printed a 50% Carbon Fibre-filled three dimensional PPS mould which has not yet been tested. Thermwood’s goal is to produce moulds that will be used in a production autoclave, moulding finished parts suitable for actual end use.

Thermwood’s additive printing process differs fundamentally from conventional Fused Deposition Modelling (FDM) printing. Most FDM processes print parts by melting and extruding a relatively small bead of thermoplastic material onto a heated build plating that is contained within a heated chamber. The heated chamber keeps the extruded material from cooling too much before the next layer is added.

Thermwood machines print a large bead at such a high rate that a heated environment is not needed. It is basically an exercise in controlled cooling. Print speed is adjusted so that each layer cools to the proper temperature just as the next layer starts to print resulting in a continuous printing process that produces high quality parts. Thermwood believes this fundamentally different approach produces superior parts.

One other feature that Thermwood engineers believe helps produce solid, void free parts, is a patent pending compression roller that follows directly behind the print nozzle, flattening the bead while fusing it tightly to the previous layer.

This 3D printed portable mini PC is the perfect DIY project for 3D printer host control

Jun 4, 2017 | By Julia

Adafruit has uploaded a new tutorial for 3D printing a portable mini PC. Featuring a 7-inch display and built-in battery, this handy and highly portable gadget works with any HDMI device, making it the perfect setup for 3D printer host control.

Posted by the Ruiz Brothers, the 7” Mini PC provides a solid alternative to a Raspberry Pi when running 3D printer interfaces such as Octoprint. Particularly when running maintenance checks and updating firmware, a full blown PC is a key tool to have, but can often be too bulky. For that reason, the Adafruit duo designed and constructed this DIY project to easily control some of their 3D printers.

“We like this because it’s actually a lot smaller to bring this over to a printer then it is to bring over a MacBook Air,” explain the Ruiz Brothers. “So much smaller that we can fit the display right inside the printer and configure printers that can only use windows software.”

In progress for some time now, the 3D printed 7” Mini PC is actually an update to Adafruit’s earlier 7-inch design. Added benefits include an easier assembly thanks to snap fit nubs (as opposed to the previously seen screws) that fasten the lid onto the case.

Mounts are an easy addition to the model, making attaching your preferred tiny computer (whether a PC or Rasperry PI) a synch. Alternatively, threads can be made directly onto the lid.

For this DIY project, the Ruiz Brothers decided to go with a PowerBoost 1000c for easy circuit powerage, ensuring a simple recharging process from the USB port on the side. The makers also included tripod compatibility into their model. The case geometry provides the option for adding a tripod-compatible screw so the whole enclosure can be mounted efficiently to a tripod. Don’t want to use a tripod? The tripod screw fits flush against the enclosure, so the mini PC can still stand upright even without the use of a tripod.

Last but not least, small interchangeable 90 degree up-angled HDMI connectors feature a nifty latching mechanism for linking up flat flexible ribbon cables. These connectors are available in all different types of angle configurations, making it easy to mix and match depending on the specific project.

To prep for this project, the Ruiz Brothers recommend checking out their previous guide for a 7″ HDMI Monitor Backpack. Required tools and accessories include a soldering iron and solder, some silicone wire, PLA filament and a desktop FDM style 3D printer. The full list of parts can be viewed here, which mainly revolves around basics that any tech-inclined makers will likely have in their toolbox. Happy DIYing!

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Researchers regenerate bone using 3D printed clay hydrogel

Researchers in China have released a manuscript detailing a 3D printable material specially designed to support the growth of bone cells. Matter grown with the support of this polymer/clay nanocomposite could be used in the treatment of bone defects caused by trauma, deformities, or the removal of tumors. It has also been tested in vivo with positive results.

Diagram of the process developed by researchers at Tianjin University, Chinese Academy of Sciences and the University of Hong Kong. Image via ACS Biomaterials Science & Engineering, May 2017

Diagram of the process developed by researchers at Tianjin University, Chinese Academy of Sciences and the University of Hong Kong. Image via ACS Biomaterials Science & Engineering, May 2017

Matching the extracellular matrix 

Hydrogels are widely used in tissue regeneration as their molecular structure resembles the naturally occurring extracellular matrix (ECM) found in living organisms. The role of an ECM, and in this case a hydrogel, is to give structure and nutrition to surrounding live cells. The right environment for support and nutrition varies depending upon the kind of tissue, e.g. arteries need a tubular structure, bone cells thrive better in porous material.

Some previous examples reported by 3D Printing Industry include a study on the combination of TPU, PLA, and graphene oxide that could be used to support bone regrowth, and soluble scaffolds 3D printed at the University of Connecticut.

This study in particular focuses on conditions conducive to bone regrowth. It does so by infusing the gel with particles of clay – a material naturally similar to human bone, and used in varying degrees to fix fractures.

Preparing the ink

The basis of the material is a hydrogen bonding, UV reactive, monomer (molecule that attaches to others) previously invented by the research team, and exhibiting highly flexible mechanical properties.

Mechanical properties of the base material. Image via ACS Biomaterials Science & Engineering, May 2017

Mechanical properties of the base material. Image via ACS Biomaterials Science & Engineering, May 2017

To this, the researchers add varying quantities of clay particles to manage the balance between the structure and the flow of the material as an ink.

The ink is extruded through a nozzle 250 μm in diameter (approximately the diameter of 5 human hairs) into a grid-like scaffold shape with linking parts, using a BioScaffolder 2.1 3D printer. The scaffold is then baked in a crosslink oven to connect the particles, and washed in de-ionized water to remove impurities.

The 3D printed hydrogel-nanoclay material as a scaffold (b), and gridded cylinder (c, e, f) Image via ACS Biomaterials Science & Engineering, May 2017

The 3D printed hydrogel-nanoclay material as a scaffold (b), and gridded cylinder (c, e, f) Image via ACS Biomaterials Science & Engineering, May 2017

In vitro and in vivo testing

Results of the tests in vitro, i.e. outside of the body in a controlled container, show positive, living, activity of rat osteoblast cells within the clay hydrogel. As a result, the researchers were able to apply the material to tibia defects in live rats.

Comparison of bone regrowth in blank (placebo) in vivo rate tests (top) and hydrogel-clay tests (bottom) Image via ACS Biomaterials Science & Engineering, May 2017

Comparison of bone regrowth in blank (placebo) in vivo rate tests (top) and hydrogel-clay tests (bottom) Image via ACS Biomaterials Science & Engineering, May 2017

One half of the test group had the hydrogel-clay implanted in the leg, and the other half recieved a blank, placebo, support. After 8 weeks of healing, the clay hydrogels proved to promote better regrowth of bone at the tibia.

Conclusions state that,

3D printing of the hydrogen bonding monomer with a variety of bioactive inorganic nanoparticles will open up a new avenue to construct load-bearing tissue engineering scaffolds for precision and individualized repair of bone defect and degeneration.

3D-printed high strength bioactive supramolecular polymer/clay nanocomposite hydrogel scaffold for bone regeneration was published online in ACS Biomaterials Science & Engineering journal as a Just Accepted Manuscript May 17, 2017. It is co-authored by Xinyun Zhai, Yufei Ma, Chunyong Hou, Fei Gao, Yinyu Zhang, Changshun Ruan, Haobo Pan, W. Lu, and Wenguang Liu, attributable to Tianjin University, Chinese Academy of Sciences and the University of Hong Kong.

For more of the latest 3D printing related research in medicine and other uses, sign up to the 3D Printing Industry newsletterlike us on Facebook and follow us on Twitter.

Featured image: Cracks in natural clay. Photo by Olli Jalonen, [email protected] on Flickr

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University of Michigan medical residents use 3D printed surgical models to practice reconstructive …

Apr 12, 2017 | By Tess

Residents from the University of Michigan Medical School in Ann Arbor have been using 3D printed surgical models and training tools to practice and hone their surgical skills in a hands-on way. The practice has reduced the need for human cadavers.

Cher Zhao, who is currently a resident at UM, took part in the innovative surgical simulations and was given the chance to practice reconstructive cartilage grafting using a 3D printed model made from a realistically textured material. The procedure, which involves cutting cartilage from the patient’s ribs to be used as grafts elsewhere in the body, relies on meticulous and exact carving. Having adequate training is therefore crucial.

Traditionally, surgical training required real bodies, whether in the form of actual patients, anaesthetized animals, or most commonly, human cadavers. As one can imagine, these are not only difficult and complicated to come by, but—in the case of cadavers—are also expensive to store and preserve. Lifelike 3D printed models, based on actual human anatomies, have provided a more than suitable alternative.

“3D printing is bringing a whole new meaning to hands-on experience for surgeons in training,” explained David Zopf, M.D., pediatric head and neck surgeon at C.S. Mott Children’s Hospital. “Hands-on experience is critical for acquiring and improving surgical skills, especially of new and complex procedures. This is an exciting tool that not only offers trainees exposure to opportunities they otherwise wouldn’t have but that also allows them to demonstrate proficiency of skills before being performed on children.”

A recent article published in Otolaryngology-Head and Neck Surgery, for which Zopf was a senior author, outlines the ways in which 3D printed surgical training models are beneficial, offering practical experience to trainees in a cost-efficient way. At the Mott Children’s Hospital, 3D printing has been used as a tool for nearly six years now, and its applications within the hospital are continuing to grow.

For instance, the technology is being used to make 3D printed splints, which have helped to save the lives of infants suffering from tracheobronchomalacia, a condition that causes the child’s windpipe to collapse, resulting in breathing difficulty. 3D printing has also been used to create models of fetuses, which have helped doctors prepare for tricky birthing situations, and even to make a replica of a patient’s skull to carefully plan a tumor removal operation.

Reconstructive cartilage grafting is the latest procedure that is benefitting from the use of 3D printed models. As Zopf commented: “Currently, a surgeon in training has scarce opportunity to carve cartilage graft for this type of procedure. We want to see if 3D printing can accelerate and enhance surgical training.”

Zhao was one of eighteen surgical trainees who participated in a UM otolaryngology head and neck surgery dissection course last year, which involved a 3D printed model of a human cartilage graft. The 3D printed model was based off a CT scan of a young patient’s rib, and was used as a mold to make cornstarch and silicone based models (which have a more realistic texture).

According to the trainees, the course offered them valuable insight and helped to advance their surgical skills. As Zhao said: “You only get one chance to carve a harvested graft from a patient’s rib, so you have to do it perfectly the first time. It takes years of practice to learn the technical skills to do it. This was a very realistic experience and what’s great is you can keep printing dozens of these models at a time so you can practice over and over again.”

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