Accounting uncertainties in forging process design variables

Abstract

Multi-stage hot forging is a plastic deformation process in which a simple shaped billet is heated to an elevatedtemperature, forged through a number of stages and cooled to room temperature. Many complex industrialcomponents, as well as many consumer goods, are produced through forging processes. In the last years thecompetitive global market of the forging industry has placed a considerable pressure on the manufacturers toreduce the overall production costs. Production cost is highly dependent on development time, tool/die life,required energy, waste material and rejected parts.Forging is a complex nonlinear process and simulation based on the finite element method has been an ongoingresearch field. Optimal forging design considering geometric and material properties of cold and hot forgingoperations has been presented. Nevertheless, uncertainties that occur during production can cause defective parts.The objective of this research is a contribution towards incorporating process uncertainties into the forging processdesign leading to robust design. The presented example consists of a two-stage forging of a pre-heated billet madeof AISI 1018 steel. First the optimal project is determined and then uncertainties are introduced in the optimaldesign variables. Using a reasonable number of data sets acquired with a finite element analysis computer model,an attempt is made to determine the variability on the forged product. This methodology allows understanding theuncertainties that determine the main final product defects. The analysis of the uncertainties of the parameters willdrive to the robust design of hot forging processes.