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1
Content available On Micromachining with a Focus on Miniature Gears by Non Conventional Processes. A Status Report
Chaudhary T., Siddiquee A. N., Chanda A. K., Khan Z. A.
Archive of Mechanical Engineering
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2018
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Vol. LXV, nr 1
129--169
EN
Recent developments in automation and technology have revolutionized the way products are made. It is directly seen in the evolution of part miniaturization in the sectors such as aerospace, electronics, biomedicine and medical implants. Micromachining is a promising technology to fulfill the need of miniaturization. A review has been done on the micromachining processes such as micro electric discharge machining (micro-EDM) and wire EDM (WEDM), micro electrochemical machining (micro-ECM). Recent literature were studied and categorized in terms of materials, process parameters, performances, product manufactured, and miniature product generation. Starting with brief introduction to micromachining, classifications and applications, technical aspects of discussions from the literature have been presented on key factors such as parameters and the response variables. Important aspects of recast layer, heat effected zone, micro-hardness, micro cracks, residual stress, etc., have been given. A special focus is given to the status of the research on microgear manufacturing. Comparison has been made between other conventional process suitable for micro-gear manufacturing and WEDM. The miniature gear machined by WEDM shows the defect-free microstructure, better surface finish, thin recast layer and improved gear quality parameters such as profile and pitch. Finally, the research gaps and future research directions have been presented.
2
Content available Friction Stir Welds of Al Alloy-Cu. An Investigation on Effect of Plunge Depth
Wahid M. A., Siddiquee A. N., Khan Z. A., Asjad M.
Archive of Mechanical Engineering
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2016
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Vol. LXIII, nr 4
619--634
EN
In the present study, butt joints of aluminum (Al) 8011-H18 and pure copper (Cu) were produced by friction stir welding (FSW) and the effect of plunge depth on surface morphology, microstructure and mechanical properties were investigated. The welds were produced by varying the plunge depth in a range from 0.1 mm to 0.25 mm. The defect-free joints were obtained when the Cu plate was fixed at the advancing side. It was found that less plunging depth gives better tensile properties compare to higher plunging depth because at higher plunging depth local thinning occurs at the welded region. Good tensile properties were achieved at plunge depth of 0.2 mm and the tensile strength was found to be higher than the strength of the Al (weaker of the two base metals). Microstructure study revealed that the metal close to copper side in the Nugget Zone (NZ) possessed lamellar alternating structure. However, mixed structure of Cu and Al existed in the aluminum side of NZ. Higher microhardness values were witnessed at the joint interfaces resulting from plastic deformation and the presence of intermetallics.
PL
W pracy przedstawiono spawy czołowe aluminium (Al) 8011-H18 i czystej miedzi (Cu) wykonane techniką spawania tarciowego z przemieszaniem (FSW). Badano wpływ zagłębienia trzpienia na morfologię powierzchni, mikrostrukturę i właściwości mechaniczne spawu. Spawy wykonano przy zmiennym zagłębieniu trzpienia narzędzia w zakresie od 0,1 do 0,25 mm. Złącza bez defektów otrzymano, gdy płyta miedziana była zamocowana po stronie natarcia przesuwu. Stwierdzono, że przy mniejszym zagłębieniu narzędzia uzyskuje się większą wytrzymałość na rozciąganie niż przy większych zagłębieniach, przy których występuje lokalne pocienienie w regionie spawania. Dobre właściwości uzyskano przy zagłębieniu 0,2 mm, a wytrzymałość spawu na rozciąganie była większa niż wytrzymałość aluminium (słabszego z dwu metali). Badanie mikrostruktury ujawniło, że metal po stronie miedzi miał w strefie rekrystalizacji (strefie ziarnistej) spawu (WNZ) strukturę płytkową o charakterze przemiennym. Natomiast mieszana struktura Cu i Al istniała w strefie rekrystalizacji po stronie aluminium.Wyższe wartości mikrotwardości były obserwowane w obszarach międzyfazowych złącza, co wynikało z odkształceń plastycznych i obecności związków międzymetalicznych.
3
Content available Effects of Cutting Parameters on Quality of Surface Produced by Machining of Titanium Alloy and Their Optimization
Niharika, Agrawal B. P., Khan I. A., Khan Z. A.
Archive of Mechanical Engineering
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2016
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Vol. LXIII, nr 4
531--548
EN
Titanium alloy (Ti-6Al-4V) has been extensively used in aircraft turbine-engine components, aircraft structural components, aerospace fasteners, high performance automotive parts, marine applications, medical devices and sports equipment. However, wide-spread use of this alloy has limits because of difficulty to machine it. One of the major difficulties found during machining is development of poor quality of surface in the form of higher surface roughness. The present investigation has been concentrated on studying the effects of cutting parameters of cutting speed, feed rate and depth of cut on surface roughness of the product during turning of titanium alloy. Box-Behnken experimental design was used to collect data for surface roughness. ANOVA was used to determine the significance of the cutting parameters. The model equation is also formulated to predict surface roughness. Optimal values of cutting parameters were determined through response surface methodology. A 100% desirability level in the turning process for economy was indicated by the optimized model. Also, the predicted values that were obtained through regression equation were found to be in close agreement to the experimental values.
PL
Stop tytanu (Ti-6Al-4V) jest szeroko stosowany do budowy elementów turbinowych silników lotniczych i innych podzespołów samolotów, elementów złącznych w technice lotniczej i astronautycznej, wysokiej jakości części samochodowych, w technice okrętowej i medycznej, a także w sprzęcie sportowym. Niemniej, powszechne zastosowanie tego stopu jest ograniczone trudnościami z jego obróbką. Jednym z podstawowych problemów jest niska jakość obrabianej powierzchni, która charakteryzuje się znaczną chropowatością. Przedstawiona praca jest poświęcona badaniu wpływu parametrów skrawania, takich jak szybkość skrawania, szybkość posuwu i głębokość skrawania na chropowatość powierzchni uzyskaną w procesie toczenia stopu tytanu. Przy zbieraniu danych nt. chropowatości powierzchni wykorzystano planowanie eksperymentu metodą Boxa-Behnkena. Do określenia poziomu istotności parametrów skrawania zastosowano metodę analizy wariancji, ANOVA. Sformułowano także równania modelu, pozwalającego przewidzieć chropowatość powierzchni. Optymalne wartości parametrów skrawania wyznaczono, stosując metodę powierzchni odpowiedzi (RSM). Wartości parametrów wyznaczone na podstawie równań regresji są bardzo bliskie wartościom uzyskanym eksperymentalnie.
4
Content available Effect of flux composition on the percentage elongation and tensile strength of welds in submerged arc welding
Singh B., Khan Z. A., Siddiquee A. N., Maheswari S., Sharma S. K.
Archive of Mechanical Engineering
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2016
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Vol. LXIII, nr 3
337--354
EN
This experimental study reveals the effects of CaF2, FeMn and NiO additions to the base fluxes on tensile strength and percentage elongation of the weld metal. The aim of this study is to develop suitable flux for mild steel for high tensile strength, impact strength and ductility. Bead on plate welds were made using submerged arc welding process. Mathematical model for percentage elongation and UTS of mild steel welds were made. The elements transfer to the welds have been correlated with the above mechanical performance characteristics. The effect of oxygen content on weld elongation and UTS also has been deduced. This study shows that CaF2 and NiO are the significant factors for tensile strength while FeMn is not significant for tensile strength. However, for elongation besides CaF2, the interaction of CaF2 and FeMn was also found significant. The effects of basicity index of the flux and carbon equivalent of the welds on tensile strength and percentage elongation of the welds have also been evaluated.
PL
W studium eksperymentalnym, przedstawionym w pracy, pokazano wpływ domieszek CaF2, FeMn i NiO do podstawowego składu topnika na wytrzymałość na rozciąganie i procentowe wydłużenie metalu spawu. Celem studium było opracowanie topnika odpowiedniego dla stali niskowęglowej, który zapewnia wysoką wytrzymałość na rozciąganie, wytrzymałość na udary i plastyczność. Ściegi spawów wykonano metodą spawania łukiem krytym. Opracowano model matematyczny wydłużenia procentowego i wytrzymałości na rozciąganie (UTS) dla spawów ze stali niskowęglowej. Zbadano korelację między wymienionymi charakterystykami mechanicznymi a transferem pierwiastków do spawu. Wyznaczono także wpływ zawartości tlenu na wydłużenie spawu i ostateczną wytrzymałość na rozciąganie. W badaniach doświadczalnych wykazano, że domieszki CaF2 oraz NiO są istotnymi czynnikami wpływającymi na wytrzymałość na rozciąganie, podczas gdy domieszka FeMn nie ma istotnego wpływu. Oceniono także wpływ współczynnika zasadowości topnika i równoważnika węglowego spawu na wydłużenie procentowe spawu.
5
Content available A novel approach to enhance performance of multilayer coated carbide insert in hard turning
Shihab S. K., Khan Z. A., Siddiquee A. N., Khan N. Z.
Archive of Mechanical Engineering
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2015
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Vol. LXII, nr 4
539--552
EN
Flank wear of multilayer coated carbide (TiN/TiCN/Al2O3/TiN) insert in dry hard turning is studied. Machining under wet condition is also performed and flank wear is measured. A novel micro-channel is devised in the insert to deliver the cutting fluid directly at the tool-chip interface. Lower levels of cutting parameters yield the minimum flank wear which is significantly affected by cutting speed and feed rate. In comparison to dry and wet machining, insert with micro-channel reduces the flank wear by 48.87% and 3.04% respectively. The tool with micro-channel provides saving of about 87.5% in the consumption of volume of cutting fluid and energy.
PL
W pracy przedstawiono badania nad zużyciem krawędzi skrawającej wielowarstwowej płytki z ceramiki narzędziowej (TiN/TiCN/Al2O3/TiN) w toczeniu twardym na sucho. Badano także zużycie krawędzi skrawającej w warunkach toczenia na mokro. Nowatorskim rozwiązaniem było zastosowanie mikrokanału w płytce skrawającej, przez który płyn smarny dostarczany jest bezpośrednio do styku między narzędziem i wiórem. Uzyskany tą drogą niższy poziom parametrów skrawania zapewnia minimalne zużycie krawędzi skrawającej, na które w istotny sposób wpływają prędkość skrawania i szybkość posuwu. W porównaniu do warunków toczenia na sucho i na mokro, zastosowanie mikrokanału zmniejsza zużycie krawędzi skrawającej o odpowiednio 48,87% i 3,04%. Narzędzie z mikrokanałem zapewnia także oszczędność zużycia płynu smarnego i energii o ok. 87,5%.
6
Content available A Study on the Effects of Human Age, Type of Computer and Noise on Operators’ Performance of a Data Entry Task
Khan Z. A., Rizvi S. A. H.
International Journal of Occupational Safety and Ergonomics
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2010
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Vol. 16, No. 4
455--463
EN
The effects of human age, type of computer, and noise on computer operators’ performance of a data entry task were investigated. Twenty male subjects aged 10–55 were assigned into 4 age groups each consisting of 5 persons. They performed the task for 15 min on desktop and laptop computers in a sitting posture under varying levels of noise. The mean number of characters entered per minute (MNCEPM) was statistically analyzed. Operators in the 16–25 age group achieved the highest rate of data entry at each level of noise investigated. Operators performed better on desktop than on laptop computers. Their performance decreased when noise level increased from 82 to 92 dB(A), but it improved at 102 dB(A). The effects of age and noise were statistically significant. However, the effects of the type of computer, the interactions between age and type of computer, age and noise level, and type of computer and noise were not found to be statistically significant.
7
Content available A Study on the Effect of Human Laterality, Type of Computer and Noise on Operators’ Performance of a Data Entry Task
Khan Z. A., Rizvi S. A. H.
International Journal of Occupational Safety and Ergonomics
|
2009
|
Vol. 15, No. 1
53--60
EN
Effects of human laterality, type of computer and noise on computer operators’ performance of a data entry task were investigated. Seven right- and 7 left-motorsided male subjects performed the task on desktop and laptop computers in a sitting posture under varying noise levels. The mean number of characters entered per minute was statistically analysed. The right-motorsided operators entered more data than left-motorsided ones at each noise level. Operators performed better on desktop computers. Operators’ performance decreased when noise level increased from 82 to 92 dB(A) but it improved at 102 dB(A). Effects of laterality, type of computer and noise, and the interaction between laterality and noise were statistically significant. The interactions between laterality and type of computer, and type of computer and noise were statistically insignificant. Laterality was statistically significant at all noise levels and noise was statistically significant for right motor-sided operators only.
8
Content available A Study on the Combined Effect of Noise and Vibration on the Performance of a Readability Task in a Mobile Driving Environment by Operators of Different Ages
Khan I. A., Mallick Z., Khan Z. A., Muzammil M.
International Journal of Occupational Safety and Ergonomics
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2009
|
Vol. 15, No. 3
277--286
EN
This study investigated the combined effect of noise and vibration on the performance of a readability task in a mobile driving environment by operators of different ages. Subjects performed a readability task on a laptop computer in a sitting posture without their backs supported under varying levels of noise and vibration. Data in terms of a mean number of characters read per minute were collected and statistically analyzed. Results showed that the individual effects of noise, vibration, and operators’ age as well as the interaction between operators’ age and vibration were statistically significant. However, the combined effect of noise and vibration was not found to be statistically significant. Results also indicated that the operators’ age was statistically significant at all levels of vibration and vibration was statistically significant at all levels of operators’ age.
9
Content available A Study on the Combined Effect of Noise and Vibration on Operators’ Performance of a Readability Task in a Mobile Driving Environment
Khan I. A., Mallick Z., Khan Z. A.
International Journal of Occupational Safety and Ergonomics
|
2007
|
Vol. 13, No. 2
127--136
EN
This paper presents a study in which the main objective was to investigate the combined effect of noise and vibration on the performance of a readability task in a mobile driving environment. Subjects performed a readability task on a laptop computer in a sitting posture with their backs supported with a backrest under varying levels of noise and vibration. The data in terms of the mean number of characters read per minute were collected and statistically analyzed. Results showed that the individual effect of noise, vibration, and the operators’ gender as well as the interaction between gender and noise, and gender and vibration were statistically significant. However, the combined effect of noise and vibration was not found to be statistically significant. Results also indicated that gender was statistically significant at all levels of noise as well as vibration, and noise and vibration were statistically significant at both levels of gender.
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