Development of an advanced materials system for tooling produced by three-dimensional printing

Abstract

Three Dimensional Printing (3DP™) is a manufacturing technique in which a powdered material is used to build parts with complicated geometries directly from a three dimensional computer model. This technique has been used in the past to manufacture metal parts with complicated geometries. The three different materials used in the making of tools by 3DP™ are binder, metal powder and the low melting infiitrant. The original material system used for hard tools is 420 martensitic stainless steel powder, a Cu-lOSn alloy as the infiltrant and acrysol as the binder. Although almost 50 tools have been manufactured using this materials system, there were several concerns which had to be dealt with, including dimensional control, porosity control, erosion and interaction between the skeleton and the infiltrant. Another requirement is a "hardenable" material system that is soft initially and that can be hardened after machining. This thesis describes the development of a new hardenable material system in which most of the concerns with the 420/bronze system are eliminated. The new material system that was selected uses a Mo powder skeleton and a 56Cu-22Ni- 22Mn infiltrant. The Cu-Ni-Mn alloy is age hardenable. Acrysol was retained as the binder material again. Experiments were carried out to study the printing, debinding/sintering and infiltration steps. An extra age hardening step was also introduced after infiltration. The process parameters for each of the steps were developed and several tools have been manufactured successfully. The thesis describes each of the post processing steps in detail with regards to experiments that were performed or literature that was obtained from past work. The tools that were manufactured with the new material system showed better properties on the whole than those manufactured with the previous material system.