Continuous-operation MIM furnace system for powder-metallurgy moulding

Metal injection moulding (MIM) is a process for near-net shape production of small metal components of complex geometry in small to medium-scale series. It combines the technology of injection moulding of polymers with that of powder-metallurgy sintering and thus permits production of high-density castings with extremely narrow tolerances. The process as such has been known for more than forty years but has been in commercial use in industry only for around fifteen. The heat-treatment stages necessary when the MIM process is used have up to now generally been performed in non-continuous heat-treatment systems. Initial tests on continuous-operation (through-flow) systems taking the form of modified PM sintering furnaces have, however, indicated that continuous processing is also possible and is capable of significantly reducing production costs. Producers of MIM injection-moulded components have most recently registered greatly increased interest from the automotive industry. The development on an innovative debindering and sintering furnace of through-flow type became necessary in order to meet the need for larger components and repeatable process conditions. This MIM furnace is made up of three process units which are specifically tailored to the respective process requirements. The article describes the new furnace installation and practical operating results from commercial production of MIM components.