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.

Manufacture of Microcantilever Sensors

2005 ◽  
Author(s):  
Andrew W. McFarland ◽  
Jonathan S. Colton ◽  
Daniel Cox ◽  
Steven Y. Liang
Keyword(s):  
Machine Tool ◽  
Mechanical Response ◽  
Surface Force ◽  
Depth Of Cut ◽  
Feed Speed ◽  
Machining Parameters ◽  
Form Accuracy ◽  
Microcantilever Sensors ◽  
Micro Scale ◽  
Sensing Applications

Mechanical micro machining is an emerging technology with many potential benefits and equally great challenges. The push to develop processes and tools capable of micro scale fabrication is a result of the widespread drive to reduce part and feature size. One important factor that contributes to the ability to machine at the microscale level is the overall size of the machine tool due to the effects of thermal, static, and dynamic stabilities. This paper explores the technical feasibility of miniaturized machine tools capable of fabricating features and parts on the micro scale in terms of depth of cut and part form accuracy. It develops a machine tool and examines its capabilities through benchmarking tests and the making of precision dies for the injection molding of microcantilever parts. The design and configuration of a miniaturized vertical machining center of overall dimension less than 300 mm on a side is presented and the component specifications discussed. The six axis machine has linear positioning resolution of 4 nm by 10 nm by 10 nm, with accuracy on the order of 0.3 μm, in the height, feed, and cross feed directions. The work volume as defined by the ranges of axes travel are 4 mm by 25 mm by 25 mm in the height, feed, and cross feed and 20 degrees in the rotational space. To quantify the performance capability of the miniaturized machine tool as a system, a series of evaluation tests were implemented based on linear and arch trajectories over a range of feed speed and depth of cut conditions. Test results suggest that micro level form accuracy and sub-micron level finish are generally achievable for parts with moderate curvature and gradient in the geometry under selected machining parameters and conditions. An injection mold was made of steel with this machine and plastic microcantilevers fabricated. Plastic microcantilevers are appropriate for sensing applications such as surface probe microscopy. The microcantilevers, made from polystyrene, were 464 to 755 μm long, 130 μm wide and only 6–9 μm thick. They showed very good uniformity, reproducibility, and appropriate mechanical response for use as sensors in surface force microscopy.

Research on Prediction Model of Surface Roughness in Ultrasonic Polishing Nano-ZrO2 Ceramics

2009 ◽  
Vol 69-70 ◽  
pp. 128-132
Author(s):  
Ming Li Zhao ◽  
Bo Zhao ◽  
Yu Qing Wang ◽  
Guo Fu Gao
Keyword(s):  
Surface Roughness ◽  
Orthogonal Test ◽  
Depth Of Cut ◽  
Feed Speed ◽  
Machining Parameters ◽  
Test Results ◽  
Work Situation ◽  
Table Speed ◽  
Abrasive Size ◽  
Regressive Analysis

The orthogonal test of surface roughness in ultrasonic polishing nano-ZrO2 ceramics was carried out in the present paper. Through the test, the influence of machining parameters on the surface roughness was investigated. The test results showed that the influence of abrasive size on surface roughness is the most remarkable, and the other important factors are the depth of cut, on/off work situation of ultrasonic generator, axial feed speed, and working table speed in turns. Furthermore, through the regressive analysis of test data, an empirical formula of surface roughness was established to select reasonable polishing parameters.

Investigations on surface roughness and microhardness of turned AM alloy

2020 ◽  
pp. 095440622097616
Author(s):  
Sunil Dutta ◽  
NSK Reddy
Keyword(s):  
Surface Roughness ◽  
Surface Integrity ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
Feed Speed ◽  
Average Roughness ◽  
Study Results ◽  
Superior Surface ◽  
Input Variables ◽  
Response Variables

Manufacturers in different sectors look for materials exhibiting good mechanical properties, high machinability, and superior surface integrity. The machinability of Mg alloys is one of the vital aspects which requires an exhaustive survey during their selection for different applications. The study examines the surface integrity of a fabricated AM alloy (Mg alloy with 7 wt%Al-0.9 wt%Mn) through dry turning. During the experiments, the input variables of turning viz. cutting speed( v), depth of cut (DOC), and feed( f) is altered and applied to the workpiece. The data obtained for the two response variables viz. surface roughness and microhardness accentuate the maximum influence of feed, followed by DOC and speed. For validation a two-stage methodology was adopted; In the first stage, the validation was done with the help of Analysis of variance (ANOVA); the results show the % contribution of feed, speed, and DOC on average roughness is 66.94%, 5.91%, and 27.23% and on microhardness is 47%, 8.3%, and 44.57%, respectively. Subsequently, in the second stage, the surface plots are drawn for both the response variables to ascertain the ANOVA outcomes; the shape of the plots corroborates the experimental and ANOVA results. The study results provide vital insights for parameter selection to get improved results on surface roughness and microhardness during machining of AM alloy.

An Investigation about the Effect of Depth of Cut on Surface Integrity in Creep Feed Grinding of INC 792-5A

2011 ◽  
Vol 320 ◽  
pp. 163-169
Author(s):  
R. Ashofteh ◽  
A. Rastkerdar ◽  
S. Kolahdouz ◽  
A. Daneshi
Keyword(s):  
Surface Roughness ◽  
Surface Integrity ◽  
Structural Changes ◽  
Depth Of Cut ◽  
Machining Parameters ◽  
Cutting Depth ◽  
Creep Feed Grinding ◽  
Creep Feed ◽  
Micro Cracks ◽  
Average Grain Size

Creep-Feed Grinding(CFG) is one of the none-traditional machining in which form grinding to full depth is performed in limited number of passes. One of the most significant criteria which is taken into account to display valid machining parameters, is surface integrity. Surface integrity in CFG process is influenced by four main factors including surface roughness, superficial micro-crack, burning and changes in micro-hardness. According to prior investigations in CFG process, depth of cut plays an important role in surface integrity. In this study, the influence of cutting depth on workpiece surface integrity of cast nickel-based superalloy with alummina wheels, was investigated. During this study, a sample part was machined with variable depth of cut while the other parameters were Constant. After machining, surface roughness of each specimen was measured and in order to investigate existence and dimensional situation of surface micro-cracks, Chemical Etch + FPI and Thermal shock + FPI were performed. For determining micro-structural changes in ground specimens as a clarifier criteria in measuring the level of residual stress, a set of recrystallization processes were carried out on them and average grain size were measured. The results show, however, changing in depth of cut hasn't influenced on micro-cracks, quality of surface roughness has descended in terms of increasing the cutting depth.

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.

The Process Strategies of Mould High-Speed Machining and their Applications in the Environment of PowerMILL

2011 ◽  
Vol 188 ◽  
pp. 542-548 ◽  
Author(s):  
Jie Liu
Keyword(s):  
High Speed ◽  
Tool Path ◽  
Cutting Parameters ◽  
Depth Of Cut ◽  
Feed Speed ◽  
Machining Parameters ◽  
High Speed Machining ◽  
Whole Process ◽  
Machining Strategies ◽  
Selection Of

High-speed machining requires the support of high intelligent CAM software as well as customized machining strategies and properly selected machining parameters. Only by combining the two can the advantage of high-speed machining be made full use of. Compared to ordinary NC cutting, high-speed machining has special requirements for process strategies, CAM system and tool path. A complete tool path includes approaching/retracting tool, moving tool and tool path. Based on the above principles, a mould part is successfully processed using the PowerMILL software at the high-speed machining centre of DMG-DMU40T. The maximum hardness of the mould part is HRC50. There’s a 30 degree corner in the cavity with a transition radius of 3mm. The whole process can be divided into three stages: rough, semi-finish and finish machining and each stage involves the selection of tool path, the selection of tool, the selection of cutting parameters (including spindle speed, feed speed and depth of cut), and the application of PowerMILL specific machining methods (such as Race-line machining, rest roughing, automatic trochoidal machining, 3D offset finishing and etc).

The Effect of Machining Parameters on Surface Integrity when Milling Hardened Steel

2014 ◽  
Vol 660 ◽  
pp. 70-73 ◽  
Author(s):  
N.H. Rafai ◽  
Mohd Amri Lajis ◽  
N.A.J. Hosni
Keyword(s):  
Surface Integrity ◽  
Subsurface Layer ◽  
Cutting Temperature ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
Machining Parameters ◽  
Radial Depth ◽  
Aisi D2 ◽  
Experimental Trials ◽  
Hardness Values

This study discussed about the influence of the cutting speed and radial depth of cut on surface integrity (microhardness and work-hardening) when performing hard milling of AISI D2 workpiece. By using PVD-TiAlN, nine experimental trials were performed at various cutting speeds of 80, 100 and 120 m/min and various radial depth of cut of 3, 4 and 5 mm as feed and depth of cut remain constant at 0.05 mm/tooth and 0.05 mm. From the result, due to high cutting temperature generated, the cutting speed adversely affects the microhardness value of the subsurface layer. At higher cutting speed of 120 m/min higher hardness values were obtained when compared with lower cutting speed of 80 m/min. As for the effect of the radial depth of cut it is clear that it influences the microhardness beneath the surface. Higher microhardness recorded from the radial depth of cut increment associated with high cutting temperature generated during machining.

Unit Machining Operations: An Automated Process Planning and Selection Program

1980 ◽  
Vol 102 (4) ◽  
pp. 297-302 ◽  
Author(s):  
R. A. Wysk ◽  
M. M. Barash ◽  
C. M. Moodie
Keyword(s):  
Process Planning ◽  
Manufacturing Systems ◽  
Metal Cutting ◽  
Depth Of Cut ◽  
Feed Speed ◽  
Machining Parameters ◽  
Automated Manufacturing Systems ◽  
Specific Product ◽  
Automated Process Planning ◽  
Automated Process

In most metal cutting or removing facilities, the task of planning piece part operations and sequences is the responsibility of the process planner. Although this individual holds the key to the profitability of a specific product, little has been done to aid the process planner in the performance of his job. With the cost of machinery skyrocketing as the degree of automation is increasing, much emphasis has been placed on process planning or engineering. This paper outlines the responsibilities and functions carried out by the process planner. The paper is primarily concerned with automated manufacturing systems and, in particular, the planning of parts on machining centers. It demonstrates the decisions required of process planner and the lack of quantifiable data available to make logical decisions at the present time. A review of the two approaches to automated process planning, called variant and generative planning, is presented. The paper also describes some of the shortcomings of classification codes that have been used for automated process planning. The framework for a computer generative process planning scheme is demonstrated. The selection of machining parameters (feed, speed and depth of cut) are also discussed.

scholarly journals Effect of Nose Radius on Surface Roughness of Diamond Turned Germanium Lenses

2021 ◽  
Author(s):  
Adeniyi Adeleke ◽  
Abou-El-Hossein Khaled ◽  
Odedeyi Peter
Keyword(s):  
Surface Roughness ◽  
Surface Finish ◽  
Single Point ◽  
Absolute Error ◽  
Diamond Turning ◽  
Machining Process ◽  
Depth Of Cut ◽  
Feed Speed ◽  
Machining Parameters ◽  
Nose Radius

Abstract The desire for quality infrared lens with better surface finish has brought about the usage of brittle materials like germanium to be machined via a single point diamond turning machining process. However, achieving the required surface finish is complex if special machining techniques and approaches are not employed. In this paper, the effect of two different tool nose radius parameters on surface roughness of single point diamond turned germanium workpiece were studied and analyzed. The machining parameters selected for this experiment were feed, speed and depth of cut. Box-Behnken design was adopted to optimally create a combination of cutting parameters. Measurement of surface roughness after each run in both experiments was achieved using a Taylor Hobson PGI Dimension XL surface Profilometer. The resulting outcomes show that at most experimental runs, the surface roughness value decreased with an increase in nose radius. Mean absolute error was also used to compare the accuracy validation of the two models.

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.

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