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Article
Publication date: 28 January 2020

Haihua Wu, Junfeng Li, Zhengying Wei and Pei Wei

To fabricate a selective laser melting (SLM)-processed AlSi10Mg part with almost full density and free of any apparent pores, this study aims to investigate the effect of…

Abstract

Purpose

To fabricate a selective laser melting (SLM)-processed AlSi10Mg part with almost full density and free of any apparent pores, this study aims to investigate the effect of ambient argon pressure and laser scanning speed on the particles splash during the AlSi10Mg powder bed laser melting.

Design/methodology/approach

Based on the discrete element method (DEM), a 3D model of random distribution of powder particles was established, and the 3D free surface of SLM forming process was dynamically tracked by the volume of fluid, where a Gaussian laser beam acts as the energy source melting the powder bed. Through the numerical simulation and process experimental research, the effect of the applied laser power and scanning speed on the operating laser melting temperature was studied.

Findings

The process stability has a fundamental role in the porosity formation, which is process-dependent. The effect of the processing conditions on the process stability and the resultant forming defects were clarified.

Research limitations/implications

The results shows that the pores were the main defects present in the SLM-processed AlSi10Mg sample, which decreases the densification level of the sample.

Practical implications

The optimal processing parameters (argon pressure of 1,000 Pa, laser power of 180 W, scan speed of 1,000 mm/s, powder layer thickness of 35 µm and hatch spacing of 50 µm ) applied during laser melting can improve the quality of selective laser melting of AlSi10Mg,

Social implications

It can provide a technological support for 3D printing.

Originality/value

Based on the analysis of the pore and balling formation mechanisms, the optimal processing parameters have been obtained, which were argon pressure of 1,000 Pa, laser power of 180 W, scan speed of 1,000 mm/s, powder layer thickness of 35 µm and hatch spacing of 50 µm. Then, a near-fully dense sample free of any apparent pores on the cross-sectional microstructure was produced by SLM, wherein the relative density of the as-built samples is larger than 97.5%.

Details

Rapid Prototyping Journal, vol. 26 no. 5
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 26 October 2018

Pei Wei, Zhengying Wei, Zhne Chen, Jun Du, Yuyang He and Junfeng Li

This paper aims to study numerically the influence of the applied laser energy density and the porosity of the powder bed on the thermal behavior of the melt and the…

Abstract

Purpose

This paper aims to study numerically the influence of the applied laser energy density and the porosity of the powder bed on the thermal behavior of the melt and the resultant instability of the liquid track.

Design/methodology/approach

A three-dimensional model was proposed to predict local powder melting process. The model accounts for heat transfer, melting, solidification and evaporation in granular system at particle scale. The proposed model has been proved to be a good approach for the simulation of the laser melting process.

Findings

The results shows that the applied laser energy density has a significantly influence on the shape of the molten pool and the local thermal properties. The relative low or high input laser energy density has the main negative impact on the stability of the scan track. Decreasing the porosity of the powder bed lowers the heat dissipation in the downward direction, resulting in a shallower melt pool, whereas pushing results in improvement in liquid track quality.

Originality/value

The randomly packed powder bed is calculated using discrete element method. The powder particle information including particle size distribution and packing density is taken into account in placement of individual particles. The effect of volumetric shrinkage and evaporation is considered in numerical model.

Details

Rapid Prototyping Journal, vol. 25 no. 9
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 May 2003

Zhengying Wei, Yiping Tang, Wanhua Zhao and Bingheng Lu

This paper describes the rapid development process for emitter which is the key part in water‐saving irrigation device. The design of labyrinth‐channel in emitters, the…

Abstract

This paper describes the rapid development process for emitter which is the key part in water‐saving irrigation device. The design of labyrinth‐channel in emitters, the generation of process‐oriented structural CAD model, the building of emitter prototype and its integrative experimental model based on RP are introduced in detail. The emitter prototypes can be directly applied to irrigation experiments and production practice, and hence the rapid development of drip irrigation emitters can be realized.

Details

Rapid Prototyping Journal, vol. 9 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 11 April 2016

Qiyin Lin, Zhengying Wei, Ning Wang and Yubin Zhang

The purpose of this paper is to study the influences of recess configurations on the performances of high-speed hybrid journal bearing. Hybrid journal bearing earns…

Abstract

Purpose

The purpose of this paper is to study the influences of recess configurations on the performances of high-speed hybrid journal bearing. Hybrid journal bearing earns increasing attention in high-speed machine tool spindle owing to its intrinsic outstanding performances of low temperature rise and high stability.

Design/methodology/approach

To investigate the coupled effects of temperature, turbulence and the interaction between lubricant and journal/bearing bush, a thermal fluid-structure interaction approach is presented and validated by the experimental results.

Findings

Ladder-type recess has excellent tribological characteristics in decreasing temperature rise, improving stability and inhibiting cavitation, which are all beneficial to improve the performances of high-speed spindle system.

Originality/value

This work can be a valuable guide for the future high-speed hybrid journal bearing design.

Details

Industrial Lubrication and Tribology, vol. 68 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 22 August 2017

Xuewei Fang, Zhengying Wei, Jun Du, Lu Bingheng, Pengfei He, Bowen Wang, Jian Chen and Ruwei Geng

This paper aimed to propose a novel fused-coating-based additive manufacturing (FCAM); the study of key process parameters and mechanical tests are performed to determine…

Abstract

Purpose

This paper aimed to propose a novel fused-coating-based additive manufacturing (FCAM); the study of key process parameters and mechanical tests are performed to determine the proper parameters when building metal components.

Design/methodology/approach

Sn63Pb37 alloy is deposited in an induction heating furnace with a fused-coating nozzle to build metal parts on a copper-clad substrate. The process parameters including nozzle pressure, nozzle and substrate temperature and nozzle gap between substrate are analyzed and found to have great influence on parts quality. The mechanical property tests between the fused-coating and casting parts are performed in horizontal and vertical directions. Also, the optical microscopy images are used to ascertain under which conditions good bonding can be achieved.

Findings

A FCAM method is proposed, and the exploration study about the manufacturing process is carried out. The critical parameters are analyzed, and microscopy images prove the suitable temperature range that requires to fabricate metal parts. The mechanical tests confirm that tensile strength of printing parts is improved by 20.4 and 11.9 per cent in horizontal and vertical direction than casting parts. The experimental results indicate that there is a close relationship between process parameters and mechanical properties.

Originality/value

This paper proves that FCAM provides an alternative way to quickly make functional metal parts with good quality and flexibility compared with other additive manufacturing methods. Moreover, good mechanical property is achieved than conventional casting parts.

Details

Rapid Prototyping Journal, vol. 23 no. 5
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 2 October 2007

Zhengying Wei, Yiping Tang, Wanhua Zhao and Bingheng Lu

The paper aims to summarize the design theory for labyrinth channels of water saving emitters.

Abstract

Purpose

The paper aims to summarize the design theory for labyrinth channels of water saving emitters.

Design/methodology/approach

On the basis of extracting the structural parameters of labyrinth channels in water saving emitters, the hydraulic performance experiments on the integral emitters fabricated with higher resolution rapid prototyping technology are performed. Then, using multivariable linear regression, formulas of pressure versus flow rate and regression plots for different emitters are induced.

Findings

The formulas of flow rate versus structural parameters are summarized based on the trapezoid‐type channel unit, and verified through experiments. The relationships between flow rate, pressure and structural parameters of channels are established.

Research limitations/implications

The effect of emitter fabrication error on the flow rate is analyzed, which provides a basis for parameterized structural design and accuracy control in the fabrication of future emitters.

Practical implications

The QHn relationship equations are used to design emitters which have flow‐rate errors under both high‐ and low‐water pressure of less than 4 percent. So the QHn relationship equation of the emitter is well proven and accurate which can guide the design for the structure of emitters with trapezoid labyrinth channels.

Originality/value

In this paper, a new stereolithography system has been used to fabricate accurately a drip irrigation emitter with a complex microstructure, which cannot be obtained with conventional RP or other manufacturing processes. Compared to other manufacturing process, this new technique has higher manufacturing accuracy and can reduce the manufacturing cost and time. Furthermore, a design theory for labyrinth channels of water saving emitters is established.

Details

Rapid Prototyping Journal, vol. 13 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 13 April 2015

Qiyin Lin, Zhengying Wei, Ning Wang and Wei Chen

The purpose of this paper is to study the influence of large-area texture/slip surface, especially the area and position of large-area texture surface on journal bearing…

Abstract

Purpose

The purpose of this paper is to study the influence of large-area texture/slip surface, especially the area and position of large-area texture surface on journal bearing, and improve the tribological performances of journal bearing.

Design/methodology/approach

A modified texture/slip numerical boundary condition with double parameters is presented and is applied onto the region where surface textures locate to represent the impact of actual texture/slip surface. A phase change condition is used to analyze cavitation phenomena.

Findings

The global/cumulative texture effect can be represented by applying texture/slip condition onto the region where it locates. The area and position of texture/slip surface would significantly affect the cavitation and load-carrying capacity. Texture/slip surface would not affect the pressure and load-carrying capacity when it locates at cavitation zone. The effect of texture/slip surface on load-carrying capacity would be beneficial if it locates at the pressure rise region, but its effect would be adverse if it locates at the pressure drop region. Well-designed texture/slip surface can improve tribological performances.

Originality/value

The developed texture/slip boundary condition can be a suitable and useful tool to analyze the effect of large-area texture/slip surface and especially to optimize the area and position of large-area texture surface. This approach can be complementary to conventional approach which is used to analyze the influence of textures’ real configurations and parameters.

Details

Industrial Lubrication and Tribology, vol. 67 no. 3
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 21 July 2020

Hualiang Ren, Qinglei Zhang and Ying Zheng

The purpose of this paper is to find the influence of employees’ work values on their creative performance and test the role of knowledge sharing among them.

Abstract

Purpose

The purpose of this paper is to find the influence of employees’ work values on their creative performance and test the role of knowledge sharing among them.

Design/methodology/approach

This work surveyed 387 employees in six companies across three cities to test the research hypothesis model.

Findings

The findings reveal that comfort and security (comfort) work values have a significant negative impact on the creative performance, whereas competence and growth (competence) work values and status and independence (status) work values have a significant positive impact on creative performance. Knowledge sharing plays a mediating role between work values and creative performance.

Originality/value

This study reveals the influence mechanism of work values on creative performance from a new perspective and confirms the differing effects of different types of work values on creative performance.

Details

Chinese Management Studies, vol. 15 no. 1
Type: Research Article
ISSN: 1750-614X

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Article
Publication date: 6 March 2017

Jinyu Yang, Bin Liu and Lihua Yuan

This paper comes to the point from the tax competition of local government in investment promotion and capital introduction. This paper aims to empirically examine the…

Abstract

Purpose

This paper comes to the point from the tax competition of local government in investment promotion and capital introduction. This paper aims to empirically examine the internal mechanism of enterprises obtaining land resources from local government and its resulting equity investment increase and economic consequences of overinvestment.

Design/methodology/approach

The data of China’s A-share listed companies from 2007 to 2014 were used to test the relationship between the increase in enterprise equity investment and the acquisition of land resources and overinvestment. The descriptive statistics, correlation analysis and least squares linear regression were used to solve the above question.

Findings

One of the reasons for the enterprise equity increase is to obtain scarce land resources. The enterprise acquisition for land resources leads to overinvestment. The equity investment increase from obtaining land resources will further stimulate enterprise group to overinvest.

Research limitations/implications

The authors could not get the actual data of land that subsidiaries have obtained directly. In this research, the authors get the data using consolidated statements and subsidiary statements indirectly.

Practical implications

The results make contributions to the influencing factors and economic consequence of the enterprise investment structural deviation.

Social implications

It provides reference to optimize the “interaction” relationship between government and enterprises.

Originality/value

It identified the “dual-channel” conduction mechanism between land resource acquisition and enterprise overinvestment.

Details

Nankai Business Review International, vol. 8 no. 1
Type: Research Article
ISSN: 2040-8749

Keywords

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