Characterization of Zirconia-Based Ceramics After Microgrinding

2019 ◽  
Vol 7 (2) ◽  
Author(s):  
Pablo Fook ◽  
Oltmann Riemer
Keyword(s):  
Surface Roughness ◽  
Flexural Strength ◽  
Residual Stresses ◽  
Machining Parameters ◽  
X Ray Diffraction ◽  
Four Point Bending ◽  
Ductile Mode ◽  
Recent Developments ◽  
Vibration Assistance ◽  
Diamond Grain

Despite the recent developments of ductile mode machining, microgrinding of bioceramics can cause an insufficient surface and subsurface integrity due to the inherent hardness and brittleness of such materials. This work aims to determine the influence of a two-step grinding operation on zirconia-based ceramics. In this regard, zirconia (ZrO2) and zirconia toughened alumina (ZTA) specimens are ground with ultrasonic vibration assistance within a variation of the machining parameters using two grinding steps and different diamond grain sizes of the tools in each of the machining procedure. White light interferometry, scanning electron microscope, X-ray diffraction (XRD), and four-point bending tests are performed to evaluate surface roughness, microstructure, residual stresses, and flexural strength, respectively. The strategy applied suggests that the finished parts are suitable for certain biomedical uses like dental implants due to their optimum surface roughness. Moreover, concerning the mechanical properties, an increase of the flexural strength and compressive residual stresses of ground ZrO2 and ZTA workpieces were observed in comparison to the as-received specimens. These results, as well as the methodology proposed to investigate the surface integrity of the ground workpieces, are helpful to understand the bioceramic materials response under microgrinding conditions and to set further machining investigations.

Prediction of Surface Roughness in Compressed Air Jet Assisted High Speed End Milling of Silicon Using Diamond Coated Tools

2012 ◽  
Vol 576 ◽  
pp. 41-45
Author(s):  
A.K.M. Nurul Amin ◽  
M.A. Mahmud ◽  
M.D. Arif
Keyword(s):  
Mathematical Model ◽  
Surface Roughness ◽  
Surface Finish ◽  
High Speed ◽  
End Milling ◽  
Silicon Wafers ◽  
Compressed Air ◽  
Machining Parameters ◽  
High Quality ◽  
Ductile Mode

The majority of semiconductor devices are made up of silicon wafers. Manufacturing of high-quality silicon wafers includes numerous machining processes, including end milling. In order to end mill silicon to a nano-meteric surface finish, it is crucial to determine the effect of machining parameters, which influence the machining transition from brittle to ductile mode. Thus, this paper presents a novel experimental technique to study the effects of machining parameters in high speed end milling of silicon. The application of compressed air, in order to blow away the chips formed, is also investigated. The machining parameters’ ranges which facilitate the transition from brittle to ductile mode cutting as well as enable the attainment of high quality surface finish and integrity are identified. Mathematical model of the response parameter, the average surface roughness (Ra) is subsequently developed using RSM in terms of the machining parameters. The model was determined, by Analysis of Variance (ANOVA), to have a confidence level of 95%. The experimental results show that the developed mathematical model can effectively describe the performance indicators within the controlled limits of the factors that are being considered.

scholarly journals Strategy of Residual Stress Determination on Selective Laser Melted Al Alloy Using XRD

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 451 ◽  
Author(s):  
Yujiong Chen ◽  
Hua Sun ◽  
Zechen Li ◽  
Yi Wu ◽  
Yakai Xiao ◽  
...  
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Residual Stresses ◽  
High Surface ◽  
Al Alloy ◽  
X Ray Diffraction ◽  
Scanning Strategy ◽  
Surface Distribution ◽  
Finished Surface ◽  
Microstructural Morphology

Selective laser melting (SLM) is known to generate large and anisotropic residual stresses in the samples. Accurate measurement of residual stresses on SLM-produced samples is essential for understanding the residual stress build-up mechanism during SLM, while a dramatic fluctuation can be observed in the residual stress values reported in the literature. On the basis of studying the influence of surface roughness on residual stress measured using X-ray diffraction (XRD), we propose a procedure coupling XRD technique with pretreatment consisting of mechanical polishing and chemical etching. The results highlight that residual stresses measured using XRD on as-built SLM-produced samples with high surface roughness are significantly lower than those measured on samples with finished surface, which is due to the stress relaxation on the spiked surface of as-built samples. Surface distribution of residual stresses and the effect of scanning strategy were systematically investigated for SLM-produced AlSi10Mg samples. Microstructural morphology was observed at the interface between sample and building platform and was linked to the surface distribution of residual stresses. This procedure can help us accurately measure the residual stresses in SLM-produced samples and thus better understand its build-up mechanism during the SLM process.

scholarly journals Structuring of Bioceramics by Micro-Grinding for Dental Implant Applications

Micromachines ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 312 ◽  
Author(s):  
Pablo Fook ◽  
Daniel Berger ◽  
Oltmann Riemer ◽  
Bernhard Karpuschewski
Keyword(s):  
Dental Implant ◽  
Surface Integrity ◽  
Depth Of Cut ◽  
Feed Speed ◽  
Machining Parameters ◽  
Metal Implants ◽  
Peripheral Speed ◽  
Grinding Processes ◽  
Recent Developments ◽  
Diamond Grain

Metallic implants were the only option for both medical and dental applications for decades. However, it has been reported that patients with metal implants can show allergic reactions. Consequently, technical ceramics have become an accessible material alternative due to their combination of biocompatibility and mechanical properties. Despite the recent developments in ductile mode machining, the micro-grinding of bioceramics can cause insufficient surface and subsurface integrity due to the inherent hardness and brittleness of these materials. This work aims to determine the influence on the surface and subsurface damage (SSD) of zirconia-based ceramics ground with diamond wheels of 10 mm diameter with a diamond grain size (dg) of 75 μm within eight grinding operations using a variation of the machining parameters, i.e., peripheral speed (vc), feed speed (vf), and depth of cut (ae). In this regard, dental thread structures were machined on fully sintered zirconia (ZrO2), alumina toughened zirconia (ATZ), and zirconia toughened alumina (ZTA) bioceramics. The ground workpieces were analysed through a scanning electron microscope (SEM), X-ray diffraction (XRD), and white light interferometry (WLI) to evaluate the microstructure, residual stresses, and surface roughness, respectively. Moreover, the grinding processes were monitored through forces measurement. Based on the machining parameters tested, the results showed that low peripheral speed (vc) and low depth of cut (ae) were the main conditions investigated to achieve the optimum surface integrity and the desired low grinding forces. Finally, the methodology proposed to investigate the surface integrity of the ground workpieces was helpful to understand the zirconia-based ceramics response under micro-grinding processes, as well as to set further machining parameters for dental implant threads.

scholarly journals INVESTIGATION OF SURFACE MACROSCOPIC RESIDUAL STRESSES OF CUTTING CERAMICS AFTER MECHANICAL MACHINING

2018 ◽  
Vol 17 ◽  
pp. 6
Author(s):  
Jakub Němeček ◽  
Jiří Čapek ◽  
Nikolaj Ganev ◽  
Kamil Kolařík
Keyword(s):  
Residual Stresses ◽  
Surface Structure ◽  
Cemented Carbides ◽  
Machining Parameters ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cutting Ceramics ◽  
Mechanical Machining

Currently, the extensive research in the field of cutting ceramics is conducted and there are efforts to replace cemented carbides by these materials. However, the problem is to improve the production of ideal compact samples. Therefore, the influence of mechanical machining technologies on the values of macroscopic residual stresses was investigated by X-ray diffraction. The resulting values were discussed depending on machining parameters and surface structure of the studied samples.

scholarly journals Effect of Speed, Feed and Depth of Cut on Machining Induced Residual Stresses in Aisi 1045 Steel

2019 ◽  
Vol 8 (2) ◽  
pp. 3397-3400 ◽  
Keyword(s):  
Residual Stresses ◽  
Depth Of Cut ◽  
Machining Parameters ◽  
X Ray Diffraction ◽  
Left Behind ◽  
Aisi 1045 Steel ◽  
Aisi 1045 ◽  
Predicted Values ◽  
Future Work ◽  
1045 Steel

Residual stress that are induced during machining of components plays a significant part in the endurance and life of the component. The magnitude and nature of the residual stresses have been of interest to many researchers across the globe. The present work involves methodology to find out the influence of factors on the residual stresses. The machining parameters were varied and the residual stresses were determined using non-destructive method, namely X-ray diffraction. Using statistical methods, the influence of the machining parameters was ascertained. This paper aims at investigating the residual stresses in AISI 1045 steel, induced due to milling. AISI 1045 steel was considered as it is a widely used material and its applications are innumerable. It was observed that speed and feed have significant influence on stresses left behind after the machining is completed. Using statistical techniques a mathematical model was developed which is further used to predict the residual stresses. The error percentage of the predicted values was less than 5%. The results obtained were promising and future work involves the optimization of the machining parameters.

Surface Roughness Effect on Pseudo-GIXRD Stress Analysis

2005 ◽  
Vol 490-491 ◽  
pp. 153-158
Author(s):  
Jun Peng ◽  
Vincent Ji ◽  
Wilfrid Seiler
Keyword(s):  
Surface Roughness ◽  
Carbon Steel ◽  
Residual Stresses ◽  
Stress Analysis ◽  
Steel Specimen ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
Roughness Effect ◽  
Destructive Analysis ◽  
Non Destructive

Residual stresses levels and their distributions in thin films have an important effect on their mechanical properties. The non-destructive analysis by pseudo-grazing incidence X-ray diffraction (GIXRD) allows us to define residual stresses gradients as a function of thin film depth. In case of pseudo-GXRD, we must take into account the effects due to surface roughness on residual stress analysis. We have investigated firstly a set of carbon steel specimens with different surface roughness (RZ varies from 4.2µm to 9.5µm) obtained by grinding. All specimens were tempered to eliminate the residual stresses due to machining. With K radiation of Chromium, Bragg peak positions were determined with various incidence angles  (varies from 1° to 78°) for each specimen. Secondly, a carbon steel specimen containing 4 zones with different surface roughness was loaded elastically in tension, pseudo-GIXRD has used for stress analysis on the loaded specimen with various incidence angles. The peak shifts due to the surface roughness were studied as function of different roughness and different incidence angles. The stress relaxation due to surface roughness was then studied.

Residual stresses in tool steel due to hard-turning

2003 ◽  
Vol 36 (5) ◽  
pp. 1135-1143 ◽  
Author(s):  
Nerea Ordás ◽  
Mari Luz Penalva ◽  
Justino Fernández ◽  
Carmen García-Rosales
Keyword(s):  
Residual Stresses ◽  
Hard Turning ◽  
Stress Gradient ◽  
Cutting Tools ◽  
Machining Parameters ◽  
X Ray Diffraction ◽  
Brittle Layer ◽  
Aisi D2 ◽  
Full Stress Tensor ◽  
Compressive Residual Stresses

Residual stresses induced by hard-turning are the result of a combination of mechanical and thermal effects, leading to a compressive or tensile stress state at the surface, depending on the machining parameters and the tool wear state. In this work, the residual stress depth profiles generated on steel grade F-521 (AISI D2) by hard-turning with tools of different wear states were measured by X-ray diffraction. An integral method was applied to determine the full stress tensor and the stress gradient tensors in the tangential, radial and depth directions. Both macroscopic and microscopic residual stresses were investigated. Compressive residual stresses were measured below the surface in all machined specimens. The magnitude of the compressive stress was much lower and the depth was much shallower when using new cutting tools than when using worn tools. However, the sample that has been hard-turned with a worn tool suffered strong microstructural changes in a layer more than 150 µm thick, especially at the surface, where the presence of a hard and very brittle layer of untempered martensite was evidenced.

Comparison of Surface Roughness Attainable in High Speed End Milling of Silicon with Air Blowing on Conventional and CNC Milling Machines

2012 ◽  
Vol 576 ◽  
pp. 19-22
Author(s):  
A.K.M. Nurul Amin ◽  
Siti Nurshahida Mohd Nasir ◽  
Noor Syairah Khalid ◽  
Muammer Din Arif
Keyword(s):  
Surface Roughness ◽  
High Speed ◽  
End Milling ◽  
Compressed Air ◽  
Depth Of Cut ◽  
Machining Parameters ◽  
Ductile Mode ◽  
Milling Machines ◽  
Air Blowing ◽  
Machined Surfaces

Review of past research indicated that ductile mode machining of silicon can produce surface roughness values as low as 0.22 µm, which is about half of 0.40 µm, the usual standard roughness value to avoid fine grinding and rough polishing operations. The current research investigated and compared the surface roughness and integrity attained in high speed end milling of silicon (using diamond coated tools) under ductile mode machining conditions. Two different types of end milling machines were utilized, CNC and conventional milling machines. Additionally, the effect of compressed air on the resultant surface roughness was investigated. The air blowing fixture, designed for mounting the compressed air hose, consisted of fixed and movable jaws, air blower clamp, fasteners, and the air gun. Air blowing was used to prevent silicon chips from settling on the machined surface, since it was observed to be an acute problem in high speed ductile mode machining of silicon. The three machining parameters: spindle speed, depth of cut, and feed rate were varied within the ranges 60,000 to 80,000 rpm, 10 to 20 µm, and 5 to 15 mm/min respectively. The resultant machined surfaces were analysed using Wyko NT 1100 and SurfTest SV-500 profilometers in order to measure the attaine surface roughnesses and surface profile. The machined surfaces had almost no deposition and was of excellent finish.

Strengthening of Si3N4 Ceramics by Laser Peening

2006 ◽  
Vol 524-525 ◽  
pp. 141-146 ◽  
Author(s):  
Koichi Akita ◽  
Yuji Sano ◽  
Kazuma Takahashi ◽  
Hirotomo Tanaka ◽  
Shin Ichi Ohya
Keyword(s):  
Surface Roughness ◽  
Bending Strength ◽  
Laser Pulses ◽  
Bending Test ◽  
Laser Peening ◽  
Test Results ◽  
X Ray Diffraction ◽  
Four Point Bending ◽  
Four Point Bending Test ◽  
Si3n4 Ceramics

Laser peening has been applied to silicon nitride (Si3N4) ceramics without any pre-coating. X-ray diffraction study revealed that plastic strain was introduced into the surface layer of the ceramics. Compressive residual stress was also imparted, which became larger with increasing peak power density of irradiated laser pulses. Surface roughness significantly increased due to ablative interaction of the surface with laser pulses. A Weibull plot of four-point bending test results clearly showed the increase of the bending strength and Weibull modulus by laser peening in spite of the increase of the surface roughness.

Effect of Machining Parameters on Surface Integrity in Dry Turning of Inconel 718

2013 ◽  
Vol 634-638 ◽  
pp. 2831-2834
Author(s):  
Xiao Li Zhu ◽  
Jin Fa Zhang ◽  
Wu Jun Chen ◽  
Ji Wen Deng
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Surface Integrity ◽  
Feed Rate ◽  
Inconel 718 ◽  
Cutting Speed ◽  
Diffraction Method ◽  
Cutting Parameters ◽  
Depth Of Cut ◽  
Machining Parameters

Surface quality including residual stresses and surface roughness due to turning operations in Inconel 718 were studied as a function of cutting speed, feed rate and depth of cut. By means of X-ray radiation diffraction method, the influence of cutting parameters on residual stress was investigated. The results show that dry cutting of Inconel 718 resulted in predominantly tensile residual stresses at the machined surface and the surface roughness increased with the increase of cutting parameters.The effects of the cutting parameters on surface integrity are investigated while employing the range analysis. From these results it was possible to select a combination of cutting speed, feed rate and depth of cut that generate favorable surface characteristics.

Sign in / Sign up

Export Citation Format

Share Document