The University of Pittsburgh has developed a depowdering solution for metal 3D printers that could significantly reduce the cost of 3D printed metal parts. Lead by Professor Albert To, a team of undergraduates has made a gyroscope-based depowdering machine. Professor To is the leader of the AMRL, or ANSYS Additive Manufacturing Research Laboratory, at Pitt and also runs the MOST AM lab, which is a cutting edge lab that develops 3D printing simulation tools. To’s ANSYS AMRL teams decided to attempt a much more hands-on project, however, with this depowdering machine, the Pitt Depowdering Machine.
Why is depowdering important?
Post-processing accounts from anywhere from 30 to 60% of the cost of a metal 3D printed part. Far from a machine driven push-button process metal printing technologies such as Powder Bed Fusion require a high degree of manual labor. Files have to be prepared by hand, support strategies have to be thought up builds have to be nested and material has to be loaded. Once the build is done the parts have to be depowdered. This usually involves a brush and vacuum cleaner. Then parts will also have to be destressed, sawed off, tumbled and may require EDM, CNC, precipitation hardening, shot peening etc. All the while a human operator will be carrying the parts around a factory. The actual 3D printing metal process is still rather artisan even though we’re promising the world that we will make millions of car parts cost-effectively. To bridge this gulf automation will be necessary. Additive Industries is including post-processing steps in the machine others are making lines of machines aimed to reduce the cost. The cool thing about adding automated conveying, destressing, EDM wire, and other systems to an existing line is that these add ons can be used to reduce costs in existing lines and be used with machines from several vendors. All of metal 3D printing’s promises and promise will have to be fulfilled through the nuts and bolts of improving and creating industrial processes. Automated post-processing is a key element of that so Pitt’s machine is very timely to say the least.
Pitt Depowdering Machine
To tells 3DPrint.com,
“The depowdering machine employs a gyroscope design that can rotate the AM build 360 degrees in two orthogonal directions. There is a vibrator that is attached to the build and vibrates the build at a high frequency so that the powders are loosened up and come out from the build as the gyroscope is rotating through different angles. There is a funnel below the gyroscope that is used to collect all the powders coming out from the build. The machine is equipped with two sieves at the bottom of the funnel to sieve the powders to the right size for re-use.”
Such a device has the power to reduce a lot of carrying around and operator time. The speed at which one could depowder a build varies enormously but as per the team’s data they should have a huge productivity increase in terms of time over existing users.
“Typically, we put an AM build on the machine for 15-30 minutes depending on the size of the parts,” To said.
That’s not all, however: the machine may also be more efficient than existing processes.
“In one test, the machine shook out 5 more grams of powders after the technician did his best to depowder manually with the aid of a vibrator.”
A vibrator in a metal 3D printing context is a rotary or tub vibrator or a vibratory finisher which is a machine where parts are mixed in with media and then vibrated to de-clog and remove powder.
If the Pitt machine performs like this in continuous operation the savings could be significant.
To says, “We are still evaluating whether to commercialize the machine and talking to other people about it at the moment.”
We would strongly encourage them to commercialize this machine. Any in line device that could really reduce the costs of 3D printed parts would make many more metal 3D printing applications possible.
Recently, Adrian V. Lee of University of Pittsburgh prepared a study for the U.S. Army Medical Research and Materiel Command regarding 3D printed medical models and breast cancer research. His findings are outlined in ‘A 3D Bioprinted Model for the Study of Premalignant Disease,’ published by the Defense Technical Information Center.
In hypothesizing that in vitro 3D bioprinted models of premalignant breast cells could help identify markers for low-risk premalignant disease, the research team was comprised of the following specialists as ultimately, they endeavored to 3D print mammary glands:
- Surgical oncologist
- Mammary gland biologist
- Biomedical engineer
- Cancer biologist
Goals were designated for each year of the study, and completed as follows:
- Year 1 – Quantify mammary gland development and find strain dependent differences.
- Year 2 – Keep characterizing development of the mammary glands.
- Year 3 – Study growth patterns of breast cells in vitro.
Mice were used extensively in the study too, with their ages corresponding to the onset of human puberty, and mammary glands not yet affected by estrus. With breeding pairs, the researchers were able to use mammary tissue for 3D imaging that could then be sent to University of Pittsburgh for 3D printing.
“This work represented the first 3D comparison of ductal architecture and patterning in inbred mouse strains of different genetic backgrounds,” states Lee. “The hypothesis for the study was that ductal patterning, and the implementation of stereotypical branching behaviors during early post-natal development differs with genetic background.”
The research team noted differences in:
- Total duct length
- Average duct length
- Total branch count
- Branch density
- Ductal segment diameter
As work progressed, the researchers began bioprinting directly with collagen Type 1 and additional ECM protein hydrogels:
“The mammary duct model we developed represents a world-first level of complexity generated using a bioprinter with multiple ECM and hydrogel components.”
In the next phase, the researchers used progenitor cells to 3D print the mammary ductal structure. Beyond that, they completed further imaging and assessing of the 3D progenitor cell (still ongoing).
Challenges occurred as they noticed a loss of structure in the models as cells began to affect the collagen detrimentally. All the bioprinted structures experienced delamination, no matter what types of cellular foundation they possessed. Growth was interrupted and characterization overall ‘inhibited.’ They redesigned the structure for better growth and quality in their research overall.
This new system, printed entirely in collagen type I, was fabricated with an inner diameter of 1.4 mm, matching the average breast. The team has now 3D printed over 25 of the bioprinted models successfully.
“In year 1 we encountered minor difficulties such as reduced fecundity in some mouse strains, but we continued these studies in year 2 and complete the mammary ductal development studies as noted above. During year 2, we had to change the design of the 3D ductal microenvironment, as the method we developed at the end of year 1 showed uneven plating of cells and delamination of collagen,” concluded the researchers. “We re-engineered the 3D ductal environment to allow perfusion and easier plating of cells. Preliminary results show that this model has better cell plating and cell survive when toxins are removed by perfusion. In year 3 (NCE) we will now study growth of cells in this microenvironment.”
3D printed medical models have made significant impacts in the past few years especially as more scientific facilities and hospitals have begun building labs onsite. From using them as guides to rebuild areas as complex as an eye socket to training medical students and even bioprinting brain tumors to learn more, models, surgical guides, implants, and devices, and changing the face of medicine today—and the lives of patients around the globe. Find out more about how 3D printed models may help in the study of breast cancer here. What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.
[Source / Images: A 3D Bioprinted Model for the Study of Premalignant Disease]