Dental Grinding of Lithium Disilicate Ceramic Prostheses Using High-Speed Rotary Cutting Instruments in In Vitro Oral Adjusting

2016 ◽  
Vol 1136 ◽  
pp. 36-41
Author(s):  
Hai Tao Ren ◽  
Xiao Fei Song ◽  
Xiao Feng Zhang

Oral adjusting of ceramic prostheses involving abrasive machining using dental high-speed rotary cutting instruments is a central process in restorative dentistry, because this process affects not only restorative quality but also patients’ comfort. However, the dental grinding process, especially dental grinding of high-strength ceramic prostheses, is less understood in clinical dentistry. This paper presents dental grinding of an innovative high-strength lithium disilicate ceramic in in vitro oral adjusting regime using a dental high-speed electric handpiece and diamond burs. The dental abrasive machining characteristics were quantitatively evaluated in terms of normal and tangential forces, force ratio, and specific grinding energy as functions of clinically relevant dental grinding variables including depth of cut and feed rate and feed direction of burs. The results showed that the dental tangential and normal forces and specific grinding energy exhibited significant dependences on depth of cut, feed rate and direction of burs, but revealed significantly small scales compared to engineering machining regime. Clinical implication was given that down grinding undoubtedly reduced the abrasive adjusting forces to relieve patients’ discomfort in oral regime. Moreover, dentists must be cautious in dental abrasive adjusting of the lithium disilicate ceramic prostheses at or beyond the specific material removal rate of 2.4 mm3/min due to significantly large forces and vibrations.

2014 ◽  
Vol 590 ◽  
pp. 294-298
Author(s):  
Pichai Janmanee ◽  
Somchai Wonthaisong ◽  
Dollathum Araganont

In this study, effect of machining parameters and wear mechanism in milling process of mold steel AISI-P20 and AISI-1050, using 10 mm twin flute type end mill diameter. The experimental results found that characteristics of milling surfaces and wear of the mill end were directly influenced by changes of parameters for all test conditions. As a result, the quality of milling surfaces also changed. However, mould steels which had the good quality surface is AISI-1050, with roughnesses of 2.120 μm. Quality milling surfaces were milled by using the most suitable parameter feed rate of 45 mm/min, a spindle speed of 637 rpm and a cut depth level of 3 mm, for both grades. Moreover, material removal rate and duration of the milling process, the milling end mills affect wear of the edge in every bite when the feed rate is low, high speed and level depth of cut at least. It was found that limited wear less will affect the surface roughness (Ra) represents the good quality surface.


2015 ◽  
Vol 1115 ◽  
pp. 12-15
Author(s):  
Nur Atiqah ◽  
Mohammad Yeakub Ali ◽  
Abdul Rahman Mohamed ◽  
Md. Sazzad Hossein Chowdhury

Micro end milling is one of the most important micromachining process and widely used for producing miniaturized components with high accuracy and surface finish. This paper present the influence of three micro end milling process parameters; spindle speed, feed rate, and depth of cut on surface roughness (Ra) and material removal rate (MRR). The machining was performed using multi-process micro machine tools (DT-110 Mikrotools Inc., Singapore) with poly methyl methacrylate (PMMA) as the workpiece and tungsten carbide as its tool. To develop the mathematical model for the responses in high speed micro end milling machining, Taguchi design has been used to design the experiment by using the orthogonal array of three levels L18 (21×37). The developed models were used for multiple response optimizations by desirability function approach to obtain minimum Ra and maximum MRR. The optimized values of Ra and MRR were 128.24 nm, and 0.0463 mg/min, respectively obtained at spindle speed of 30000 rpm, feed rate of 2.65 mm/min, and depth of cut of 40 μm. The analysis of variance revealed that spindle speeds are the most influential parameters on Ra. The optimization of MRR is mostly influence by feed rate. Keywords:Micromilling,surfaceroughness,MRR,PMMA


2019 ◽  
Vol 130 ◽  
pp. 01031 ◽  
Author(s):  
The Jaya Suteja ◽  
Yon Haryono ◽  
Andri Harianto ◽  
Esti Rinawiyanti

Polyacetal is commonly used as bushing material because of its low coefficient of friction and self lubricant characteristics. The polyacetal is machined by using boring process to produce bushing in certain surface roughness. The objectives of this research are to optimize three independent parameters (depth of cut, feed rate and principal cutting edge angle) of boring process of polyacetal using high speed steel tool to achieve the highest material removal rate and the required surface roughness. Response Surface Methodology is used to investigate the influence of the parameters and optimize the boring process. The research shows that the influence of the boring process parameters on polyacetal is similar compared to on metal. The result reveals that the optimum result is achieved by applying the value of depth of cut, feed rate, and principal cutting edge angle is 2.9 × 10–3 m, 0.229 mm rev–1, and 99.1° respectively. By applying these values, the maximum material rate removal achieved in this research is 1263.4 mm3 s–1 and the surface roughness achieved is 1.57 × 10–6 m.


Author(s):  
Amar ul Hassan Khawaja ◽  
Mirza Jahanzaib ◽  
Shahzad Zaka

The aim of this research is to study the machinability aspects of hardened AISI 4340 High Strength Low Alloy (HSLA) steel (50 ± 2 HRC (Hardness Rockwell C)). The experimental investigation using coated carbide inserts is carried out during the dry hard milling process in a sustainable environment. The input parameters in the study are speed, feed rate and depth of cut and the responses are Average surface Roughness (Ra) and Material Removal Rate (MRR) that are selected through screening. Central Composite Design (CCD) in response surface methodology has been utilized as the experimental design technique with twenty experiments. Analysis of variance has been employed to examine the momentous machining parameters and responses. A mathematical model has been developed to optimize the surface roughness and material removal rate. It has been observed that the most significant factor for Ra is feed rate while for MRR depth of cut is the most significant factor. The results show that the minimum value of Ra ~ 0.098 μm is achieved at speed ~ 1000 RPM, feed rate ~ 300 mm/min and depth of cut ~ 0.2 mm while the maximum value of MRR ~ 6.35 cm3/min is attained at feed rate ~ 500mm/min and depth of cut ~ 0.4 mm regarding less or no effect of speed ~ 500-1000 RPM. The average forecast error for the validation information has been observed to be 3.35%. for Ra and 3.2% for MRR. Further, it is investigated that good surface finish like grinding and dimensional accuracy can be achieved with coated carbide tools.


2014 ◽  
Vol 903 ◽  
pp. 194-199
Author(s):  
Mohd Zairulnizam Zawawi ◽  
Mohd Ali Hanafiah Shaharudin ◽  
Ahmad Rosli Abdul Manaf

Machining technique using high spindle speed, high feed rate and shallow depth of cut utilize in High Speed Milling (HSM) machines offer several benefits such as increase of productivity, elimination of secondary and semi-finishing process, reduce tool load and small chips produced. By adjusting some of the machining parameters, non-HSM machine having lower spindle speed and feed rate could also take advantages some of the benefits mentioned above when applying the HSM technique. This experiment investigate the effects of varying combination of depth of cut and feed rate to tool wear rate and surface roughness during end milling of Aluminum and P20 tool steel in dry condition. The criterion for tool wear before it gets rejected is based on maximum flank wear, Vb of 0.6mm. Material removal rate, spindle speed and radial depth of cut are constant in this experiment. After preliminary machining trials, the combination starts with depth of cut of 2mm and feed rate of 45mm/min until the smallest depth of cut and highest feed rate of 0.03mm and 3000mm/min respectively. The obtained result shows that for both materials, feed rate significantly influences the surface roughness value while depth of cut does not as the surface roughness value keep increasing with the increase of feed rate and decreasing depth of cut. Whereas, tool wear rate almost remain unchanged indicates that material removal rate strongly contribute the wear rate. With no significant tool wear rate, this study demonstrates that HSM technique is possible to be applied in non-HSM machine with extra benefits of eliminating semi-finishing operation, reducing tool load for finishing, machining without coolant and producing smaller chip for ease of cleaning.


2006 ◽  
Vol 532-533 ◽  
pp. 349-352
Author(s):  
Wen Xiang Zhao ◽  
Si Qin Pang ◽  
Zhen Hai Long ◽  
Xi Bin Wang

35CrMnSiA, is a kind of important engineering materials that used widely in modern manufacturing fields. The machinability of 35CrMnSiA Steel with hardness of HRc40±2 in high speed turning process was studied in this paper. It is concluded that, when high speed turning of this ultra-high strength alloy steel, the chief wear mode of ceramics is the crater on rake faces; the interaction of depth of cut and feed rate is one of statistic significant effects on cutting force; the interaction of cutting velocity of cut and feed rate is one of statistic significant effects on surface roughness Ra; besides, the empirical formula of average cutting temperature, cutting forces, surface roughness Ra, was established.


Author(s):  
A. Pandey ◽  
R. Kumar ◽  
A. K. Sahoo ◽  
A. Paul ◽  
A. Panda

The current research presents an overall performance-based analysis of Trihexyltetradecylphosphonium Chloride [[CH3(CH2)5]P(Cl)(CH2)13CH3] ionic fluid mixed with organic coconut oil (OCO) during turning of hardened D2 steel. The application of cutting fluid on the cutting interface was performed through Minimum Quantity Lubrication (MQL) approach keeping an eye on the detrimental consequences of conventional flood cooling. PVD coated (TiN/TiCN/TiN) cermet tool was employed in the current experimental work. Taguchi’s L9 orthogonal array and TOPSIS are executed to analysis the influences, significance and optimum parameter settings for predefined process parameters. The prime objective of the current work is to analyze the influence of OCO based Trihexyltetradecylphosphonium Chloride ionic fluid on flank wear, surface roughness, material removal rate, and chip morphology. Better quality of finish (Ra = 0.2 to 1.82 µm) was found with 1% weight fraction but it is not sufficient to control the wear growth. Abrasion, chipping, groove wear, and catastrophic tool tip breakage are recognized as foremost tool failure mechanisms. The significance of responses have been studied with the help of probability plots, main effect plots, contour plots, and surface plots and the correlation between the input and output parameters have been analyzed using regression model. Feed rate and depth of cut are equally influenced (48.98%) the surface finish while cutting speed attributed the strongest influence (90.1%). The material removal rate is strongly prejudiced by cutting speed (69.39 %) followed by feed rate (28.94%) whereas chip reduction coefficient is strongly influenced through the depth of cut (63.4%) succeeded by feed (28.8%). TOPSIS significantly optimized the responses with 67.1 % gain in closeness coefficient.


2016 ◽  
Vol 836-837 ◽  
pp. 168-174 ◽  
Author(s):  
Ying Fei Ge ◽  
Hai Xiang Huan ◽  
Jiu Hua Xu

High-speed milling tests were performed on vol. (5%-8%) TiCp/TC4 composite in the speed range of 50-250 m/min using PCD tools to nvestigate the cutting temperature and the cutting forces. The results showed that radial depth of cut and cutting speed were the two significant influences that affected the cutting forces based on the Taguchi prediction. Increasing radial depth of cut and feed rate will increase the cutting force while increasing cutting speed will decrease the cutting force. Cutting force increased less than 5% when the reinforcement volume fraction in the composites increased from 0% to 8%. Radial depth of cut was the only significant influence factor on the cutting temperature. Cutting temperature increased with the increasing radial depth of cut, feed rate or cutting speed. The cutting temperature for the titanium composites was 40-90 °C higher than that for the TC4 matrix. However, the cutting temperature decreased by 4% when the reinforcement's volume fraction increased from 5% to 8%.


2016 ◽  
Vol 78 (6-9) ◽  
Author(s):  
Mohd Shahfizal Ruslan ◽  
Kamal Othman ◽  
Jaharah A.Ghani ◽  
Mohd Shahir Kassim ◽  
Che Hassan Che Haron

Magnesium alloy is a material with a high strength to weight ratio and is suitable for various applications such as in automotive, aerospace, electronics, industrial, biomedical and sports. Most end products require a mirror-like finish, therefore, this paper will present how a mirror-like finishing can be achieved using a high speed face milling that is equivalent to the manual polishing process. The high speed cutting regime for magnesium alloy was studied at the range of 900-1400 m/min, and the feed rate for finishing at 0.03-0.09 mm/tooth. The surface roughness found for this range of cutting parameters were between 0.061-0.133 µm, which is less than the 0.5µm that can be obtained by manual polishing. Furthermore, from the S/N ratio plots, the optimum cutting condition for the surface roughness can be achieved at a cutting speed of 1100 m/min, feed rate 0.03 mm/tooth, axial depth of cut of 0.20 mm and radial depth of cut of 10 mm. From the experimental result the lowest surface roughness of 0.061µm was obtained at 900 m/min with the same conditions for other cutting parameters. This study revealed that by milling AZ91D at a high speed cutting, it is possible to eliminate the polishing process to achieve a mirror-like finishing.


2011 ◽  
Vol 418-420 ◽  
pp. 1482-1485 ◽  
Author(s):  
Erry Yulian Triblas Adesta ◽  
Muataz Al Hazza ◽  
Delvis Agusman ◽  
Agus Geter Edy Sutjipto

The current work presents the development of cost model for tooling during high speed hard turning of AISI 4340 hardened steel using regression analysis. A set of experimental data using ceramic cutting tools, composed approximately of Al2O3 (70%) and TiC (30%) on AISI 4340 heat treated to a hardness of 60 HRC was obtained in the following design boundary: cutting speeds (175-325 m/min), feed rate (0.075-0.125 m/rev), negative rake angle (0 to -12) and depth of cut of (0.1-0.15) mm. The output data is used to develop a new model in predicting the tooling cost using in terms of cutting speed, feed rate, depth of cut and rake angle. Box Behnken Design was used in developing the model. Predictive regression model was found to be capable of good predictions the tooling cost within the boundary design.


Sign in / Sign up

Export Citation Format

Share Document