Materials flow for different lubricants during cold forming

Abstract

Purpose

Barreling contour variations on the free surfaces of cylindrical upset specimen are to handle measuring for different upsetting reductions and different lubrication conditions in this study. The purpose of this paper is to address this issue.

Design/methodology/approach

The materials flow for various materials using different lubricants in upsetting was investigated in this study. SAE 1020 steel, commercially pure copper and CuZn40Pb2 brass were used as the test materials. 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, and with a capacity of 150 metric tons.

Findings

Variations of barrel radius change clearly with increasing deformation ratio depending on lubricant type. Radius values are different to each other for SAE 1020, Cu and brass specimens. It was understood that surface roughness effect is negligible at material types. The highest radius values were obtained for the brass among all the materials for the same deformation ratio. The materials flow is hard for brass specimens because of its brittleness which is due to cold drawing so its barrel radii are high. On the contrary, SAE 1020 and copper are more suitable for the plastic deformation. As shown in the Figures, the higher radius values were obtained especially with grease lubricant for brass specimens.

Research limitations/implications

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

Practical limitations

The friction at the faces of contact retards the plastic flow of metals and the surfaces and in its vicinity. A conical wedge of a relatively undeformed metal is formed immediately below it, while the rest of the cylinder metal suffers high strain hardening and bulges out in the form of a barrel. This demonstrates that the metal flows most easily towards the nearest free surface which is the point of least resistance. However, the use of lubricants reduces the degree of bulging and under the conditions of ideal lubrication, the bulging can be brought down to zero.

Originality/value

The main value of this paper is to contribute and fulfil the detailed the dependency of barrel radius on material type by upsetting of specimen of various materials using different lubricants that are being studied so far in the literature.

Citation

Sahin, M., Çetinarslan, C. and Misirili, C. (2013), "Materials flow for different lubricants during cold forming", Industrial Lubrication and Tribology, Vol. 65 No. 5, pp. 287-296. https://doi.org/10.1108/ILT-02-2011-0011