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Article
Publication date: 6 March 2009

Wisley Sales, Marcelo Becker, Clovis S. Barcellos, Jánes Landre, John Bonney and Emmanuel O. Ezugwu

The purpose of this paper is to evaluate the performance of cutting fluid applied by minimum quantity technique when milling AISI 4140 steel with TiAlN coated cemented carbide…

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Abstract

Purpose

The purpose of this paper is to evaluate the performance of cutting fluid applied by minimum quantity technique when milling AISI 4140 steel with TiAlN coated cemented carbide inserts.

Design/methodology/approach

The vegetable oil based cutting fluid evaluated was applied through a nozzle at the centre of the tool holder under vaporized conditions with a flow rate between 0 (dry cutting) and 200 ml/h, at 50 ml/h increments. Tool wear (based on maximum flank wear, VBmax), surface roughness parameters (Ra and Rt) and burr formation (length of burr, h) were recorded and evaluated. Scanning electron microscope images and energy dispersive X‐ray analysis of the worn tools show adhesion as the dominant wear mechanism.

Findings

Encouraging tool performance was recorded when milling AISI 4140 steel due to improved lubrication and cooling at the cutting interfaces. Increase in cutting fluid flow rate improves tool life with gradual reduction of the surface roughness parameters and negligible influence on the burr length generated.

Practical implications

Results can be immediately applied on the shop floor.

Originality/value

The results show the improvement in tool wear after increase of the flow rate of the cutting fluid, applied by minimum quantity technique.

Details

Industrial Lubrication and Tribology, vol. 61 no. 2
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 27 September 2011

Eder Costa, Nelis Luiz, Marcio da Silva, Alisson Machado and Emmanuel Ezugwu

This paper seeks to evaluate the influence of tellurium content on the machinability of the microalloyed pearlitic steel (DIN 38MnS6). Two grades of steels were used, one with…

541

Abstract

Purpose

This paper seeks to evaluate the influence of tellurium content on the machinability of the microalloyed pearlitic steel (DIN 38MnS6). Two grades of steels were used, one with high (27 times greater) tellurium content and one with a low tellurium content. Machinability of the steel was determined by the number of holes drilled by the tool before undergoing severe deformation. The drilling test matrix was prepared using a fractional factorial design with five input variables studied at two levels (25‐1). Other variables investigated include cutting speed (45 and 60 m/min), feed rate (0.15 and 0.25 mm/rev), geometry of the twist drills and use of minimum quantity lubrication (MQL) at the flow rates of 30 and 100 ml/h. Statistical analysis of the results revealed that composition of the work material was most influential on tool performance. Addition of tellurium to the steel significantly improved machinability, increasing the number of drilled holes by over 100 per cent. The MQL flow rate was the least influential as increase in the flow from 30 to 100 ml/h reduced drill life only by about 9 per cent.

Design/methodology/approach

The drilling tests were carried out in the vertical position, up‐down, without pre‐holes (full drilling). Cutting speeds of 45 and 60 m/min and feed rates of 0.15 and 0.25 mm/rev were employed. Drills with two sharpening types were tested. Cutting fluid used was vegetable based and applied using the MQL technique at flow rates of 30 and 100 ml/h. The rejection criterion adopted was severe deformation of the drills and the number of machined holes was used to measure the machinability of the material.

Findings

Of all the variables investigated in this study, the least influential on drill performance is the MQL flow rate. Increase in the flow rate from 30 to 100 ml/h reduced drill performance by 9 per cent, contrary to expectation. This is a result of the cooling‐lubricant action balance promoted by the cutting fluid applied in low quantities (MQL). The most influential variable on drill performance is addition of Te to the work material which gave over twofold (103 per cent) improvement in drill performance at the cutting conditions investigated. The Te particles act at the chip‐tool interface, reducing the work necessary to shear the material during chip formation. Increase in both the cutting speed and the feed rate both lowered drill performance during machining due to associated increase in cutting temperature which tended to accelerate thermally related wear mechanisms.

Originality/value

This work was conducted to evaluate the machinability of a novel alloyed steel employed in the automobile industry. Drilling was considered as most automobile components especially the engine block is designed with many holes which require drilling process.

Details

Industrial Lubrication and Tribology, vol. 63 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 23 April 2024

Chibueze Anosike, Rita Chinenye Osefo, Nnanyelugo Ogechukwu Isiogugu, Emmanuel Chijiekwu Nwachukwu, Ugonna Kyrian Agu, Jonathan Chimaobi Nwaji and Mario-Ephraim Afam Ogbu

This study aims to determine the prevalence and predictors of postpartum depression (PPD) among nursing mothers in Nsukka, Nigeria.

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Abstract

Purpose

This study aims to determine the prevalence and predictors of postpartum depression (PPD) among nursing mothers in Nsukka, Nigeria.

Design/methodology/approach

This study was a descriptive cross-sectional survey among nursing mothers in three hospitals in Nsukka, Nigeria. Data was collected using a self-administered Edinburgh Postpartum Depression Scale (EPDS) and sociodemographic form. The data obtained were analyzed using descriptive statistics, chi-square test and binary logistic regression.

Findings

A total of 270 nursing mothers participated in this survey, giving a response rate of 94.4%. The prevalence of PPD among the study group was 20.0%. However, women who did not have complications during childbirth were about two times (AOR = 0.417, 95% CI = 0.204, 0.852, P = 0.016) less likely to develop symptoms of PPD than women who experienced birth complications. In addition, women who had poor relationships with their partners have approximately seven times (AOR = 6.994, 95% CI = 1.110, 44.059, P = 0.038) higher odds of developing PPD compared with those women who had excellent relationships with their partners.

Research limitations/implications

The sample size was small, hence, might limit the generalizability of its findings beyond the study group. Health-care practitioners should provide appropriate interventions to women at a higher risk of developing PPD on the need to maintain a healthy and supportive relationship with their partners.

Originality/value

This study provides unique insight into PPD among nursing mothers and its determinants from a different regional, socioeconomic, societal expectations, social support system, access to health care and cultural context.

Details

Mental Health and Social Inclusion, vol. 28 no. 6
Type: Research Article
ISSN: 2042-8308

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