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Article
Publication date: 5 August 2014

Cenk Misirli

The purpose of this paper is to apply the upsetting process to cylindrical specimens using flat end dies in which three types of lubricants were used. In many industrial…

235

Abstract

Purpose

The purpose of this paper is to apply the upsetting process to cylindrical specimens using flat end dies in which three types of lubricants were used. In many industrial processes, friction and lubrication have major advantages and are key during the metal forming process. Upset forging is a process which increases the diameter of the work-piece by compressing its length.

Design/methodology/approach

The materials flow for various materials using different lubricants in upsetting was investigated in this study. AISI 304 austenitic-stainless steel and commercially pure aluminium (Al99.7) were used as the test materials. The upsetting process was applied to the cylindrical specimens using flat end dies. Three types of lubricants, namely, grease, graphite and SAE 40 oil, were used in this study. Experiments were performed using a hydraulic press, which has 5 mm/s ram speed, with a capacity of 150 metric tons. On the other hand, finite element methods (FEMs) have been carried out to analyse the forming performance for displacement prediction in the barrelling process.

Findings

The results showed that the measured radius of the curvature of the barrel seemed to confirm the calculation values used before the initiation of the experimental process. It has been observed that the surface roughness had no considerable effect on the barrelling contour changes on the free surfaces, as it showed an increasing deformation ratio for all materials and lubricant types. However, minimum friction at the interface seems to occur with the grease lubricant. The present analyses show that FEMs, which can be used in the rapid prediction of required barrelling process displacements, are more suitable for use in a pressure distribution analysis for the development of the barrelling radius.

Research limitations/implications

It would be interesting to search the material flow for more different materials and lubricants. It could be a good idea if future work could be concentrated on the material flow on upsetting by using different lubricants.

Practical implications

Open-die forging, which is also known as the upsetting process, is one of the simplest forging operations used in bulk deformation processes. This operation can be explained as a solid work-piece which is positioned between two flat dies, and then with the aid of compression, the height of the work-piece is reduced under controlled working parameters during the upsetting process, in which friction and surface roughness are the major parameters playing an important role on the material flow. In a cold upsetting process, one of the undesirable conditions is that barrelling occurs as a consequence of friction between the work-piece and the die surfaces. The existence of this frictional constraint directly affects the plastic deformation of the work-piece, as friction causes barrelling in upsetting processes. However, it has been observed that the use of lubricants reduces the degree of bulging.

Social implications

This paper will be useful for industrial applications.

Originality/value

The main value of this paper is to contribute and fulfil in detail the material flow of various materials using different lubricants that are being studied so far in the literature.

Details

Industrial Lubrication and Tribology, vol. 66 no. 5
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 9 March 2015

Mumin Sahin, Cenk Misirli and Dervis Özkan

– The purpose of this paper is to examine mechanical and metallurgical properties of AlTiN- and TiN-coates high-speed steel (HSS) materials in detail.

343

Abstract

Purpose

The purpose of this paper is to examine mechanical and metallurgical properties of AlTiN- and TiN-coates high-speed steel (HSS) materials in detail.

Design/methodology/approach

In this study, HSS steel parts have been processed through machining and have been coated with AlTiN and TiN on physical vapour deposition workbench at approximately 6,500°C for 4 hours. Tensile strength, fatigue strength, hardness tests for AlTiN- and TiN-coated HSS samples have been performed; moreover, energy dispersive X-ray spectroscopy and X-ray diffraction analysis and microstructure analysis have been made by scanning electron microscopy. The obtained results have been compared with uncoated HSS components.

Findings

It was found that tensile strength of TiAlN- and TiN-coated HSS parts is higher than that of uncoated HSS parts. Highest tensile strength has been obtained from TiN-coated HSS parts. Number of cycles for failure of TiAlN- and TiN-coated HSS parts is higher than that for HSS parts. Particularly TiN-coated HSS parts have the most valuable fatigue results. However, surface roughness of fatigue samples may cause notch effect. For this reason, surface roughness of coated HSS parts is compared with that of uncoated ones. While the average surface roughness (Ra) of the uncoated samples was in the range of 0.40 μm, that of the AlTiN- and TiN-coated samples was in the range of 0.60 and 0.80 μm, respectively.

Research limitations/implications

It would be interesting to search different coatings for cutting tools. It could be the good idea for future work to concentrate on wear properties of tool materials.

Practical implications

The detailed mechanical and metallurgical results can be used to assess the AlTiN and TiN coating applications in HSS materials.

Originality/value

This paper provides information on mechanical and metallurgical behaviour of AlTiN- and TiN-coated HSS materials and offers practical help for researchers and scientists working in the coating area.

Details

Industrial Lubrication and Tribology, vol. 67 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 16 September 2013

Mumin Sahin, Murat Dinç and Cenk Misirli

– The purpose of this paper is to examine mechanical and metallurgical properties of AlTiN coating HSS materials in detail.

379

Abstract

Purpose

The purpose of this paper is to examine mechanical and metallurgical properties of AlTiN coating HSS materials in detail.

Design/methodology/approach

In this study, high-speed steel (HSS) parts were processed by the way of machining and were coated with AlTiN on physical vapour deposition (PVD) workbench at approximately 650°C for 4 h. Tensile strength, fatigue strength and hardness tests for AlTiN coated HSS samples were performed. Samples were also analyzed by energy dispersive X-ray analysis (EDS), X-ray diffraction (XRD) and scanning electron microscope (SEM). The results were compared with uncoated HSS components.

Findings

It was found that an amorphous aluminium-oxide layer emerges on surface of parts by AlTiN coating. This layer prevents further oxide formations. The coating thickness of AlTiN-coated sample is between 1,530 and 1,558 μm. Compared to uncoated HSS, AlTiN coated HSS gives higher performance.

Research limitations/implications

It would be interesting to search different coatings for cutting tools. It could be the good idea for future work concentrated wear properties on tool materials using different coatings.

Originality/value

This paper provides information on mechanical and metallurgical behaviour of AlTiN coated HSS materials and offers practical help for the researchers and scientists working in the coating area.

Details

Industrial Lubrication and Tribology, vol. 65 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

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