The economic growth of any country depends upon the MSMEs as it plays a vital role in GDP and employment. The transportation is considered as the lifeline of the country. Hence due to developing ...countries, the industries and vehicles are continuously increasing to fulfil industrial or domestic requirements. But unfortunately, industries and vehicles emit harmful gases as exhaust to the environment. Which directly or indirectly impact the human health. Fresh and clean air is the prime need of the society. Hence the monitoring of different gas concentrations in the environment is very essential to take preventive steps to control air pollution. The traditional method of monitoring the air quality is very expensive, hence most of the countries have limited air monitoring stations. In the field of nanotechnology, scientists have developed different types of soft metal oxide materials that are capable of sensing different gases at low concentrations and can work in different environmental conditions. For the last 10 years, ferrite-based sensors have the primarily used to detect harmful gases, and pollutants from vehicle exhaust, and environmental pollution monitoring. These soft ferrites have excellent electrical and magnetic properties that can also be tuned according to the requirement of the sensor to increase sensitivity and selectivity. The tuning of ferrite sensors depends upon synthesis technique, optimizing preparation conditions, sintering temperatures, operating temperatures, dopant concentration, etc This paper is based on a deep study of the synthesis techniques of nano-ferrites, different types of gas sensors, gas sensing mechanisms, parameters, and application of chemo-resistive metal oxide gas sensors. The key parameters for the ferrite gas sensors are phase formation, crystallite size, grain size, surface area, selectivity, dopants, sensitivity, gas concentration, operating temperature, and response/recovery time. This review paper also includes the study of different researchers to find the impact of high concentrations of gases like hydrogen (H
2
), carbon monoxide (CO), carbon dioxide (CO
2
), oxygen (O
2
), ethylene glycol
(
CH
2
OH
)
2
,
methane (CH
4
), ammonia (NH
3
) liquid petroleum gas (LPG), acetylene (C
2
H
2
), and nitrogen oxides (NOx) in the environment and the metal oxide materials selected for the sensor application.
Highlights
Application of metal oxide semiconductors as chemo-resistive gas sensors for monitoring different gases in domestic and industries.
Gas sensing mechanism for N-type, P-type and Mixed and substituted spinel chemo resistive metal oxides sensors.
Role of chemo-resistive metal oxide gas sensors for monitoring concentrations of different gases like Nitrogen dioxide (NO
2
), Methane (CH
4
), Ammonia (NH
3
), Acetylene (C
2
H
2
), Carbon monoxide (CO), Liquid Petroleum Gas (LPG), Ethylene glycol
(
CH
2
OH
)
2
,
Hydrogen (H
2
), and Carbon dioxide (CO
2
) in the environment.
This paper reports on the study of series of tungsten doped Ni0.5Zn0.5WxFe2−xO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) ferrites synthesized by a co-precipitation scheme. The crystallite size varies from ...62 to 49 nm and the scanning electron microscope (SEM) images show the spinel cubic structure of the powder sample. Energy Dispersive X-ray Fluorescence Spectroscopy (EDXRF) confirms the presence of Ni, Zn, W and Fe elements in the prepared samples. The specific surface areas of the Ni0.5Zn0.5W0.2Fe1.8O4, Ni0.5Zn0.5W0.4Fe1.6O4 and Ni0.5Zn0.5W0.6Fe1.4O4 samples calculated from Brunauer-Emmett-Teller (BET) method are 18.9 m2/g, 21.5 m2/g and 24.6 m2/g, respectively. The metal oxide pellet type resistive sensor was made for gas sensor application. These sensors are selective for hydrogen (H2) gas. The performance of these sensors for sensing hydrogen gas at a concentration of 1000 ppm in the temperature range 80–300 °C has been investigated. Platinum electrodes were deposited on all the pellets by RF sputtering technique. The subsequent decomposition of platinum oxides on the metal oxide pellet surface results in an increase in surface roughness and electrical resistivity. The sensor shows a change in resistance from 1.21 × 105 Ω to 7.83 × 104 Ω in the presence of H2 gas even at alow temperature. The composition with x = 0.2 at an optimum temperature of 180 °C showed a fast response (14 s) and recovery time (20 s). High sensitivity, low cost, long term stability, high selectivity and fast response at low temperature makes this sensor useful for industrial applications.
The continuous improvement of small and medium enterprises is the prime requirement for all industries to sustain and grow in the competitive international market. A systemized organized industry ...improves the quality, safety, and morale of the employees. In the present scenario, most industries are using CNC or DNC machines for high production; but the process variation can occur in most manufacturing industries. This variation in the process always affects the product's quality, which may be due to special or common causes. Lean Six Sigma (LSS) is a systematic, disciplined, and statistical set of tools adopted by most industries to improve themselves. Lean tools help eliminate the non-value-added activities, which reduce the production cost, whereas the six-sigma improves the product's quality by eliminating the process variation. The net gain to the industry can be calculated by comparing the Key Performance Indicators (KPIs) before and after the implementation of LSS. Hence, most industries are implementing LSS to improve production and quality. This paper is a case study of an automobile filters manufacturing industry, facing the problem of rejection in the fuel filters about 12%. Value stream map (VSM) and DMAIC (Define, Measure, Analyze, Improve and Control) cycle were used to improve processes to reduce the rejection rate. Tools like process capability, control charts, Pareto chart, and fishbone diagram were used in this industry for improvement. As a result, the rejection rate was reduced drastically, from 12% to 4%. The delivery cycle to customer is also reduced from 12 days to 11 days.
To satisfy the customer needs and to fulfil the competitive market requirement it becomes essential for manufacturing enterprises to reduce the rejection. The present work is focused on reduction of ...various painting defects like uncover, paint rundown, peel-off, orange peel by optimizing the properties of paint materials and different pre-treatment paint processes. These paint defects arises due to different reasons such as viscosity of the paint material, pH of paint material and paint material to thinner ratio. The pre-treatment of material before painting like Phosphating, Degreasing, Derusting and Passivation of the material also affect the quality of painted products. The properties of paint materials and pre-treatment processes are optimised using Lean Six Sigma (LSS) and Robust Taguchi Design (RTD). The define phase uses the tools like pareto charts, project charter and voice of business that shows the critical stage involves paint material properties and pre-treatment in the spray-painting process. In analysing phase, main factors that cause defects are spotted as viscosity, cleaning temperature, air pressure by using fishbone diagram. The improve phase focuses on refining the main factors responsible for rejection by using Robust Taguchi design methodology. In control phase, the procured results are implemented. This case study deals with selection of paint material properties in the organization manufacturing the agro products facing the rejection (about 12% monthly) problem dominantly due to paint defects. The data collected from the company is investigated deeply for analysing and observing the rejection causes. The implementation of adopted methodology disclosed a fall in rejection rate from 12% to 5% by optimizing the paint material properties. The implemented methodologies improve the sigma level from 2.8 to 4.1. The improved paint material properties and optimized process parameters result in better quality of agro products and good market share of agriculture equipment manufacturing organization.
This paper has covered the elimination of process variation to remove the wastages in the gear manufacturing industry. The well-known DMAIC (Define-Measure-Analyze-Improvement-Control) approach, ...which is the part of Six Sigma was used to decrease process variability, which contributes to a decrease the waste, thus improves total business efficiency. DMAIC methodology has been adopted for this research work in which various tools have been used, such as SIPOC (Supplier, Input, Process, Output, Customer), Pareto analysis, MSA (Measurement System Analysis), SPC (Statistical Process Control), Root & Cause analysis. A Bull gear product of the Company was selected for the improvement as this product has the highest rate of rejection. The variation in Measurement over Teeth (MOT) and Pitch circle diameter (PCD) were two defects which had a major contribution to rejection. When the framework was successfully deployed, Bull Gear rejection level was reduced from 10641.08 to 13193.21 ppm (part per million) and the sigma level increased from 4.37 to 4.81 with the sigma shift. These results demonstrated the impact of the lean six-sigma initiative at the gear company, which has operational efficiency and improved consistency to improve business performance and accommodate customer’s needs.
Cd doped Mn–Zn nanoferrites of the composition Mn0.4Zn0.6CdxFe2−xO4, with (0.0≤x≤0.5) have been synthesized by a co-precipitation method. The X-ray diffraction patterns of the samples confirmed the ...formation of a single-phase cubic spinel structure. Average crystallite size is found to be in the range of 35–40nm, which is in consistence with transmission electron microscopy results. The average grain size as calculated from scanning electron microscopy is found to be 100nm. DC resistivity is found to be about 10 times higher than the reported values. Specific saturation magnetization is observed to be increasing from 25.23emu/g to 48.93emu/g with cadmium concentration. Magnetic moment is increasing from 1.07BM to 2.35BM with increasing concentration of Cd2+ ions. Variation of anisotropy constant as a function of concentration of doping is also discussed. Comparatively higher DC resistivity, refined crystallite size and improved magnetization are the main achievements of the present investigation.
Biomaterials technology has advanced significantly in recent years and 2D nanostructures have played a key role in this advancement. A new ceramic 2D nanomaterial, MXene, made up of transition metal ...carbides, carbonitrides and nitrides with a planar layout that was produced by etching away “A” from a ceramic phase called “MAX”, has emerged to overcome the shortcomings of traditional biomaterials. MXene is used inadequately in biomedical applications due to its weak stability in physiological conditions, lack of prolonged and low biodegradability, and self‐controlled drug release. These drawbacks have given rise to the idea of using MXene/Polymer nano composites, due to their major properties like large surface area, metallic conductivity, biocompatibility, hydrophilicity, and size tunability. Polymer functionalization is possible by the surface‐available functional groups. This review has been done to focus on cutting‐edge examples such as polymer functionalized composites MXene for the developing field of biomedical applications. These applications consist of precise and prolonged antimicrobial activity, bio sensing, therapeutics, drug delivery, contrast‐enhanced diagnostic imaging, tissue engineering, flexible electronics, and bone regeneration.
In recent years biomaterials technology has advanced significantly and 2D nanostructures have played a key role in this advancement. A new ceramic 2D nanomaterial, MXene, has emerged to overcome the shortcomings of traditional biomaterials. This review focuses on cutting‐edge examples such as polymer functionalized composites MXene for the developing field of biomedical applications.
•Selection of product for the Lean Manufacturing in an Automobile components Manufacturing Industry.•Identification of type of wastage in the industry.•Reduce the defects after eliminating process ...variation using six sigma DMAIC tool.
Continuous improvement in the manufacturing industries is the prime requirement to make the organization profitable. Lean manufacturing and six sigma are old techniques to improve the production of the industry by eliminating waste. These tools help the industry to grow worldwide in the competitive environment. This paper is based on the case study of a well-known automobile transmission components manufacturing industry. This industry manufactures about 33 types of axles for different vehicles and was facing the problem of rejection in one of its rear axle components. The industry was losing Rs. 7,33,000/- every month due to rejection of this rear axle. Lean six sigma (LSS) was the tool implemented to find and eliminate wastages. The current state map was made for this product by using historical three months data from the industry. The layout of the shopfloor was changed to reduce the transportation of the product and to manage the space for best utilization. 5S was implemented to make everything easily assessable. Drastic improvements have been achieved after the successful implementation of LSS like the rejection rate was reduced from 10.4% to 3.20 %. The shop floor area for processing the axles has been reduced from 252 m2 to 90 m2 after change in layout. The distance travelled by the material was reduced from 4050 m to 809 m. The sigma level was also improved from 3.34 to 3.94. The lead time was reduced from 12 days to 11 days.
•Lean Manufacturing implementation in SMEs.•KPIs used to analyze the production.•Improve the flow of material in Industry.
The economy of any nation depends upon small-medium enterprises (SMEs), ...which are the largest contributor to the manufacturing business. Unfortunately, most of the SMEs are running sick because of operational inefficiencies, poor management, unskilled labor, over inventory, high rejection rate, or impaired machine parts. Value Stream Mapping (VSM) as one of the tools of lean manufacturing is accepted by most of the industries to remove non-value-added activities. This paper is a case study of an XXX Ferrites core manufacturing industry facing a problem of rejection of about 9% daily in the domain of large size ferrite cores. Selection of high rejection rate of large size Product No. UU9330 soft ferrite core emerged as a focus for the study. The researchers drew the current state map with detailed information, and the map was studied thoroughly for observing the causes of rejection. We drew the future state map after incorporating the learnings from the prevailing scenario and lean methodology. VSM implementation revealed a decrease in the rejection rate from 9% to 2%. The net gain observed in synchronization ratio and delivery performance was 7% and 25% respectively. The lead time also reduced from 10 days to 9 days after the successful lean implementation.
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