3-D Printing and Toolless Mold Technology Provide Metal Matrix Composite Parts in Days.Cast metal matrix composite Metal matrix composite A material in which a continuous metallic phase (the matrix) is combined with another phase (the reinforcement) that constitutes a few percent to around 50% of the material's total volume. (MMC See MultiMediaCard and Microsoft Management Console. ) components [reinforced with ceramic particles at high-volume fraction (30% or more)] are valued for their high stiffness, specific stiffness, wear resistance, fatigue strength, high temperature strength and creep resistance. However, these beneficial properties also make the components difficult to machine, requiring net-shape or near-net-shape casting to minimize machining operations. This requirement often limits the application of MMC components because current technologies for making net-shape MMC parts rely on costly, limited-life graphite or steel machined molds or dies for the pressure infiltration casting operation. With that in mind, Metal Matrix Cast Components, Inc., Waltham, Massachusetts One of the early centers of the Industrial Revolution in northern America, Waltham is a city in Middlesex County, Massachusetts, United States. The population was 59,226 at the 2000 census. , developed a process for making netshape ceramic preforms or final metal-infiltrated composite parts without machined dies or molds. It relies on a 3-D printing process to fabricate a net-shape ceramic preform pre·form tr.v. pre·formed, pre·form·ing, pre·forms 1. To shape or form beforehand. 2. To determine the shape or form of beforehand. n. 1. . Three-dimensional printing of ceramic shapes is a technology that allows the fabrication fabrication (fab´rikā´sh  n),n the construction or making of a restoration. of almost any imaginable 3D shape by printing it layer-by-layer directly from a CAD file. The preform with attached paraffin wax gates is coated with mold release agents and invested into a ceramic refractory compound. The process then uses Advanced Pressure Infiltration Casting (APIC (Advanced Programmable Interrupt Controller) A circuit that handles the priority of interrupts in a computer. Designed to support symmetric multiprocessing (SMP), the APIC handles more interrupts and is more flexible than the programmable interrupt controller ) to create the casting. APIC heats the metal in a vacuum/pressure chamber. When the metal is molten, a vacuum is isolated in the mold cavity. The difference between applied pressure and the vacuum isolated within the mold cavity causes infiltration of the preform. After the pressure infiltration creates the cast component, the refractory shell is blasted away with water jets. The combination of the preform and molding processes mean that a preform can be produced in a matter of hours, and a composite part can be completed in a matter of days. Another benefit is that the composite preform provides dramatic gains in the quality and consistency of the finished casting. Castings demonstrate higher strengths and fracture toughness In materials science, fracture toughness is a property which describes the ability of a material containing a crack to resist fracture, and is one of the most important properties of any material for virtually all design applications. without the defects observed when using injection molding injection molding n. A manufacturing process for forming objects, as of plastic or metal, by heating the molding material to a fluid state and injecting it into a mold. and slurry cast preforms. In addition, molds containing ceramic preforms for pressure infiltration casting traditionally were confined to highend aerospace and defense segments of the market because of high tooling costs. The combination of these processes eliminates the need for tooling and opens them up to a broader range of the market. |
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