Zoning lubricant die application for improving formability of box-shaped deep drawn parts

 The ‘formability’ of sheet metal is a major keyword referring to process design in the sheet
metal forming industry. Higher formability could reflect lower production costs and time. Many
studies have been carried out to improve formability in various ways, by using the finite element
method and experimental approaches. In the present research, a new zoning lubricant technique
is proposed. The stainless steel SUS304 square deep drawn box is used as an investigative model.
Based on the material flow analysis, we found that zoning lubricant die application could reduce the
difference in material flow velocity between wall and corner zones. This material flow characteristic
resulted in decreased nonconcurrent plastic deformation during the deep drawing process, as well
as decreased stretching in the cup wall and the delaying of the fracture. In the present research, the
design of the zoning lubricant die was strictly concerned with achieving functionality related to the
friction coefficient, area of zoning, and blank-holder pressure. A smaller friction coefficient positioned
in the corner zone and larger friction coefficient positioned in the wall zone are recommended. It
was revealed that, by appropriate zoning lubricant die application, formability could be increased in
terms of box height by approximately 7 mm or 10%.