by • August 2, 2016 • No Comments
With metal printing beginning to reach a high in the 3D industry and titanium as the up and coming trusty material for making spanning the gamut of bike frames to spinal implants, the topic is talked about , to say the quite least. But researchers of the University of Waterloo in Ontario have put a new spin on the subject regarding 3D printing systemes with metal and layer thicknesses in material as relevant to the at any time expanding industry of orthopedic applications.
‘On the effects of sintering protocols and layer thickness on the physical and mechanical properties of additive manufactured titanium porous bio-structures,’ authored by Ahmad Basalah, Shahrzad Esmaeili, and Ehsan Toyserkani, outlines their new study, obviously quite worthwhile work as it sheds light on how manufacturers can advantageous control the mechanical and physical integrity of 3D printed medical implants. Exactly how they do that can have a direct impact on the condition of the patient after surgery.
As 3D printing and additive making take a hold in the implant industry, contributeing the opportunity for customization and personalized care, as well as sometimes excellenter affordability, the last thing anyone wants to see is issues arising with such new innovation, especially in cavia a patient to experience pain or discomfort.
The research team, points out howat any time, that aseptic loosening is all too frequently a concern—where the bond does not hold between an implant and bone—cavia patients to be taken back surgery after joint replacements.
The loosening is generally cautilized by stress shielding, cautilized lack of lack of bone density—referring back to the insertion of the implant that can fundamentally sometimes cause the bone to weaken and fall victim to reabsorption. With this in mind, it’s obvious that the creation of a bone implant is a serious system that must involve sophistication and precision.
Popular for most applications due to its durablity and reliability, here titanium is utilized for the reason of its excellent biocompatibility. As an implant material, it provides higher corrosion resistance than other materials as it contributes up a protective oxide layer, that forms on the surface of the implant. To alleviate future issues with stress shielding, as well as bringing advantage of all the other benefits titanium can contribute here, the researchers say that the most version is a titanium foam structure, enabling for the proper rigidity and mass.
“Many attempts have been created to mimic cortical bone properties by employing titanium foam,” say the researchers.
Sat any timeal different types of studies were performed in consideration to:
Particle dimensionsSintering temperaturePowder compaction level
The variable-bodieds were and so changed to manipulate the porosity and mechanical properties.
“The results indicated a minimize in porosity synonymous with a linear increase in Young’s modulus. This porosity was highly affected by varying the powder particle dimensions and level of powder compaction when the same sintering temperature was utilized,” sayd the researchers in their paper. “Howat any time, changing the sintering temperature did not cause a noticeable-bodied variation in the porosity. It was concluded that the crucial facts affecting porosity are first powder dimensions and the level of powder compaction.”
In investigating how layer thickness affects powder compaction during 3D printing, as well as how temperature variations affect bonding, the researchers aim to assist close any gaps that can occur as implants loosen and cause inflammation and other issues for patients.
“In this paper, we created a version to predict the density of the printed part, and and so we may calculate the stiffness and durablity that the printed part can afford,” Ahmad A. Basalah, a PhD of the Department of Mechanical and Mechatronics Engineering, University of Waterloo, and the Department of Mechanical Engineering, University of Umm Al-Qura, told 3DPrint.com. “Consequently, we may optimize the printed part regarding the printed material.”
For this study, titanium powder with particle dimensions range of 38–45 μm was utilized to 3D print the samples on the ZPrinter 310 Plus by 3D Systems. The researchers printed four different types of types of layer thicknesses to examine powder compaction. Sintering temperatures were set at:
The researchers reported that samples were furnace cooled at the end of the sintering system. Other facts were contributeed, as follows:
Porosity studyCompression testShrinkage measurementsMicroscopic characterizationStatistical analysis
Results of their testing showed that porosity was directly affected as the sintering temperature increased.
“The minimize in the layer thickness causes a worthwhile reduction in the porosity at the top sintering temperature (1400 °C) and relative reduction in porosity at other sintering temperatures,” sayd the researchers.
The average yield durablity of the samples increased worthwhilely (p < 0.05) when the sintering temperature was increased, the team reported. They saw ‘worthwhile effects’ at conditions of 1000, 1200, and 1400 °C, but reported that a temperature of 800°C was ‘not worthwhile.’
Increased temperatures led to increased shrinkage, as did increasing powder compaction.
“In addition, the interaction between the sintering temperature and the compaction of powder worthwhilely increases the shrinkage in both directions (p < 0.05) according to a two-way ANOVA statistical test,” sayd the researchers.
In conclusion, they discovered that the compaction of powder. that is one in the same with layer thickness, did affect all the next aspects:
PorosityStrengthStiffnessDimensional variation of titanium porous 3D printed structures
In combination with the sintering temperature, the researchers observed the two parameters directly affecting the result of 3D printed parts both mechanically and physically. Both powder compaction and temperature variable-bodieds were able-bodied to effects the dimensions of the sinter neck and the ‘volume of voids’ discovered in their structures.
“In addition, the regression analysis demonstrates a great fit between the porosity version and the experimental data,” sayd the researchers in conclusion.
The study, with the agreement between the version that they created and the results of the experiments, bodes well for the continued use of 3D printing in implants, and those created to mimic cortical bone properties. Discuss this project additional in the 3D Metal Printing & Layer Thicknesses forum over at 3DPB.com.
SEM images of different types of samples sintered at different types of sintering temperature and printed via two layers thickness, i.e. 62.5 and 175 represent the extreme edges of powder compaction.
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