In Vitro Dental Cutting of Feldspar and Leucite Glass Ceramics Using an Electric Handpiece

2012 ◽  
Author(s):  
Xiao-Fei Song ◽  
Jianhui Peng ◽  
Ling Yin ◽  
Bin Lin
Keyword(s):  
Material Removal Rate ◽  
Glass Ceramic ◽  
Material Removal ◽  
Removal Rate ◽  
Chip Thickness ◽  
Glass Ceramics ◽  
Undeformed Chip Thickness ◽  
Normal Forces ◽  
Specific Material ◽  
Abrasive Cutting

Glass ceramics are important restorative materials in dentistry. They are used as veneer-core bilayer all-ceramic or metal-fused ceramic restorations or monolithic inlays/onlays/crowns to replace missing or damaged tooth structures for aesthetic and functional purposes. However, glass ceramic materials, such as feldspar and leucite glass ceramics, which are subject to this investigation, are brittle and easily induced microfractures in abrasive cutting using dental handpieces and coarse burs. In this paper, we investigated the dental abrasive cutting characteristics of feldspar and leucite glass ceramics using a high-speed electric handpiece and coarse diamond burs. Cutting forces, specific removal energy, surface roughness and morphology were investigated as functions of specific material removal rate and maximum undeformed chip thickness. The results indicate that increasing the specific material removal rate or the maximum undeformed chip thickness resulted in increases in both tangential and normal forces, but a decrease in specific removal energy for both ceramics. Tangential, normal forces and specific removal energy were significantly larger in up cutting than those in down cutting. Surface roughness for the two ceramics was not affected by the specific removal rate or the maximum undeformed chip thickness. Both microfrature and ductile microcutting morphology were observed in the machined surfaces for both ceramics. There existed a brittle to ductile transition trend when decreasing the specific material removal rate or the maximum undeformed chip thickness for the two ceramics. In comparison with feldspar glass ceramic, leucite glass ceramic generated better surfaces due to its more ductile deformation occurring in dental cutting.

Specific Material Removal Rate Calculation in Five-Axis Grinding

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Raja Kountanya ◽  
Changsheng Guo
Keyword(s):  
Material Removal Rate ◽  
Material Removal ◽  
Tool Path ◽  
Removal Rate ◽  
Unit Length ◽  
Chip Thickness ◽  
Impeller Blade ◽  
Tool Profile ◽  
Specific Material ◽  
Five Axis

Specific material removal rate (MRR) q′ was calculated for five-axis grinding in a virtual machining simulation environment (VMSE). The axis-symmetric tool rotational profile was arc-length parameterized. The twisted grazing curve due to the concurrent translation and rotation in every move was modeled through an exact velocity field and areal MRR density q″, positive in the front of the grazing curve on the tool surface. Variation of q′ and equivalent chip thickness h within the instantaneous engagement contour were deduced from q″. Illustrative results with a five-axis impeller blade finishing simulation are shown. The results were benchmarked against an average q′ calculated from the instantaneous MRR from the VMSE. As a function of time, maximum chip thickness hmax within the extents of contact along the tool profile in every move showed more isolated peaks than corresponding qmax′. Maximum cumulative material removed per unit length Qmax′ along the tool profile from all the moves was calculated to predict axial location of maximum risk of cutter degradation.  Qmax′ and hmax are useful metrics for tool path diagnosis and tool wear analysis.

A Machining Science Approach to Dental Cutting of Glass Ceramics Using an Electric Handpiece and Diamond Burs

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
Xiao-Fei Song ◽  
Jian-Hui Peng ◽  
Ling Yin ◽  
Bin Lin
Keyword(s):  
Surface Roughness ◽  
Cutting Forces ◽  
High Speed ◽  
Removal Rate ◽  
Chip Thickness ◽  
Glass Ceramics ◽  
Specific Cutting Energy ◽  
Dental Ceramics ◽  
Cutting Energy ◽  
Specific Material

Dental cutting using handpieces has been the art of dentists in restorative dentistry. This paper reports on the scientific approach of dental cutting of two dental ceramics using a high-speed electric handpiece and coarse diamond burs in simulated clinical conditions. Cutting characteristics (forces, force ratios, specific removal energy, surface roughness, and morphology) of feldspar and leucite glass ceramics were investigated as functions of the specific material removal rate, Qw and the maximum undeformed chip thickness, hmax. The results show that up and down cutting remarkably affected cutting forces, force ratios, and specific cutting energy but did not affect surface roughness and morphology. Down cutting resulted in much lower tangential and normal forces, and specific cutting energy, but higher force ratios. The cutting forces increased with the Qw and hmax while the specific cutting energy decreased with the Qw and hmax. The force ratios and surface roughness showed no correlations with the Qw and hmax. Surface morphology indicates that the machined surfaces contained plastically flowed and brittle fracture regions at any Qw and hmax. Better surface quality was achieved at the lower Qw and the smaller hmax. These results provide fundamental data and a scientific understanding of ceramic cutting using electric dental handpieces in dental practice.

Modeling Material Removal Rate of Heavy Belt-Grinding in Manufacturing of U71Mn Material

2016 ◽  
Vol 693 ◽  
pp. 1082-1089 ◽  
Author(s):  
Rong Quan Wang ◽  
Jian Yong Li ◽  
Yue Ming Liu ◽  
Wen Xi Wang
Keyword(s):  
Material Removal Rate ◽  
Material Removal ◽  
High Efficiency ◽  
Removal Rate ◽  
Low Cost ◽  
Belt Grinding ◽  
Abrasive Particles ◽  
Grinding Conditions ◽  
Modeling Material ◽  
Abrasive Cutting

The heavy belt-grinding is a new machining method, which combined the characters of heavy-duty grinding and belt-grinding together, with high efficiency and low cost. In the present paper the removal rate model of heavy belt-grinding in manufacturing of U71Mn steel is established. It is assumed that the distribution of the abrasive particles protrusion height of the abrasive belt surface closes to Gaussian distribution. The model is presented by calculating the removal volumes of all abrasive grains contributing to cutting action based on the probability theory, elastic-plastic mechanics and abrasive cutting theory. It is analysis that the material removal rate depends essentially on the mechanical properties of the workpiece and the belt and the grinding conditions. It is proportional to the average pressure, belt velocity and the indentation depth and is inverse proportion to the grain size.

Influence Of Tool Motions On Chip Thickness And Material Removal Rate

2006 ◽  
Vol 21 (4) ◽  
pp. 237-239
Author(s):  
L. Saï ◽  
W. Bouzid ◽  
A. Zghal
Keyword(s):  
Material Removal Rate ◽  
Material Removal ◽  
Removal Rate ◽  
Chip Thickness ◽  
On Chip

Particularities of Grinding High Speed Steel Punching Tools

2011 ◽  
Vol 325 ◽  
pp. 177-182 ◽  
Author(s):  
Peter Krajnik ◽  
Radovan Drazumeric ◽  
Jeffrey Badger ◽  
Janez Kopač ◽  
Cornel Mihai Nicolescu
Keyword(s):  
Simulation Model ◽  
Material Removal Rate ◽  
Temperature Rise ◽  
Material Removal ◽  
High Speed ◽  
Removal Rate ◽  
High Speed Steel ◽  
Maximum Temperature ◽  
Specific Grinding Energy ◽  
Specific Material

A simulation model of a punch grinding process has been used to determine optimal parameters to reduce grinding cycle time and achieve a constant-temperature no-burn situation. Two basic outputs of the simulation model include arc length of contact and specific material removal rate that are both time-variant. A thermal model is included in the simulation to calculate maximum grinding temperature rise. The simulation-based optimization can help to avoid thermal damage, which includes thermal softening, residual tensile stress, and rehardening burn. The grindability of high speed steel (HSS) is presented in terms of specific grinding energy versus undeformed chip thickness and maximum temperature rise versus specific material removal rate. It is shown that for a given specific material removal rate lower temperatures are achieved when grinding fast and shallow. Higher temperatures, characteristic for slow and deep grinding, soften the material leading to a lower specific grinding energy, especially if grinding is timid. Lowest values of specific grinding energy can be achieved in fast and shallow grinding at aggressive grinding conditions.

scholarly journals Influence of the Anode Material and the Flushing Gas on the Dry Electrical Discharge Machining Process

2013 ◽  
Vol 7 (5) ◽  
pp. 581-592
Author(s):  
Raoul Roth ◽  
◽  
Beck Lukas ◽  
Hartmi Balzer ◽  
Friedrich Kuster ◽  
...  
Keyword(s):  
Material Removal Rate ◽  
Electrical Discharge ◽  
Material Removal ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
Machining Process ◽  
Work Piece ◽  
Specific Material ◽  
Environmentally Friendly Process ◽  
Dry Electrical Discharge Machining

In the last years dry electrical discharge machining (DEDM) has been proposed as an alternative to the traditional EDM. The main reason for these efforts is the absence of a liquid dielectric which results in a simpler and environmentally friendly process. This paper presents measurements of the material removal rate in function of different tool electrodes, work piece materials and flushing gases put in relation with the breakdown behavior of the process. Evaluation of absolute and current specific material removal rate are presented. The data show a big influence on the material removal rate depending on the combination of work piece material and flushing gas. Two different effects are observed, the first enhancing the removal per spark and the second one reducing the short circuiting occurrence. The share of these two effects on the enhancing of the absolute material removal rate also differs in function of the work piece material. It is suggested that the chemical reaction strongly influences the process in two different ways, on one hand releasing a surplus of energy and on the other hand changing the debris particles’ properties.

Experimental Research of Grinding Force and Specific Grinding Energy of TC4 Titanium Alloy in High Speed Deep Grinding

2009 ◽  
Vol 76-78 ◽  
pp. 55-60 ◽  
Author(s):  
Xiao Min Sheng ◽  
Kun Tang ◽  
Jian Wu Yu ◽  
Hai Qing Mi
Keyword(s):  
Titanium Alloy ◽  
Material Removal ◽  
High Speed ◽  
Removal Rate ◽  
Chip Thickness ◽  
Grinding Force ◽  
Specific Grinding Energy ◽  
Undeformed Chip Thickness ◽  
Tc4 Titanium Alloy ◽  
Grinding Power

Focusing on the characteristic of hard-to-grind for titanium alloy, experiments were conducted about grinding TC4 titanium alloy under high speed deep grinding (HSDG) condition. The changing of grinding force per unit area with maximum undeformed chip thickness hmax and equivalent cutting thickness aeq are analyzed in this paper. The effect of maximum undeformed chip thickness hmax and specific material removal rate Zw' on specific grinding energy es, material removal mechanism and consumption of grinding power in HSDG process are also discussed. The experiment results reveal that application of HSDG can improve machining efficiency of grinding TC4.

Effects of Process Parameters on Surface Roughness and MRR in the hard turning of EN 36 steel

2018 ◽  
pp. 102-110
Author(s):  
Amritpal Singh ◽  
Rakesh Kumar
Keyword(s):  
Surface Roughness ◽  
Material Removal Rate ◽  
Material Removal ◽  
Hard Turning ◽  
Control Parameter ◽  
Removal Rate ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
Cutting Condition ◽  
Dry Cutting

In the present study, Experimental investigation of the effects of various cutting parameters on the response parameters in the hard turning of EN36 steel under the dry cutting condition is done. The input control parameters selected for the present work was the cutting speed, feed and depth of cut. The objective of the present work is to minimize the surface roughness to obtain better surface finish and maximization of material removal rate for better productivity. The design of experiments was done with the help of Taguchi L9 orthogonal array. Analysis of variance (ANOVA) was used to find out the significance of the input parameters on the response parameters. Percentage contribution for each control parameter was calculated using ANOVA with 95 % confidence value. From results, it was observed that feed is the most significant factor for surface roughness and the depth of cut is the most significant control parameter for Material removal rate.

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