A new research foundry adopts a series of flexible melting and forming capabilities that suggest a new range of possibilities for low-pressure die-casting.
Diecasting has earned considerable attention from industrial designers in recent years, regarding finished products and consequently production systems. This is mainly the outgrowth of those designers’ efforts to develop lighter versions of standard products, in automotive manufacturing most obviously. Those efforts led to the development of structural castings and drivetrain parts designed in aluminium alloys, for volume production. High-pressure die-casting is adopted to manufacture parts that might otherwise be produced by sand casting or investment casting, often to be followed by extensive finish machining and assembly. HPDC makes it possible to produce highly detailed but lighter engine and drivetrain components, lighter structural parts, and possibly to eliminate some post-production steps.
The next turn in this tale involves systems for producing those parts, and the recent emergence of super-sized machines to produce lightweight die-castings of expanded dimensions.
And both of these ongoing trends will leave some asking: What else can die-castings do? Germany’s Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) opened a new research operation in Wolfsburg, Germany, to address that question, but there the focus is on low-pressure die-casting.
Low-pressure die-casting accounts for a much smaller proportion of all die-casting operations than HPDC. Typically, it is applied for alloys with low melting points (e.g., aluminium alloys) and parts weighing up to 150kg. The advantages of LPDC are that it can form very high-strength parts with complex geometries and excellent dimensional accuracy. Solid castings with thick walls are typical applications, such as light-alloy automotive wheels, but also some chassis and drivetrain components and housings.
IFAM’s LPDC foundry is intended to host applied research projects, with conventional melting and casting capabilities for aluminium but also higher-temperature melting, for example for copper alloys. This multi-functionality is possible thanks to both direct and indirect induction melting and a “crucible quick-change system.” It can melt standard metals (aluminium, copper, brass, bronze, magnesium, or steel) as well as non-metallics, like salt mixtures.
Currently, salts are a medium being studied for “lost core” processes using HPDC to develop hollow castings, like engine and battery housings. IFAM suggests its new foundry could be a centre for researching salt cores in low-pressure die-casting.
The new foundry’s furnace is a 110 litre, 130kW vessel for melting at up to 1 650°C, with casting pressure up to 1.0 bar. The 1 310mm by 1 290mm lower mounting surface can accommodate moulds weighing up to 3 500kg. The upper mounting surface of 1 200mm by 1 200mm allows a maximum clamping force of 60 metric tons.
A vertically movable furnace chamber allows free accessibility of the melting crucible, for quick alloy changes. In addition to the flexible processing of different melts, the plant can work with conventional steel moulds, as well as sand or semi-moulds.
Fraunhofer IFAM also has invested in a Kurtz AL 16-12 LPDC system, to be commissioned later this year.
The new plant concept was developed in collaboration with TEGISA Giessereianlagen und Industrieöfen GmbH, based on a prototype in operation at Fraunhofer IFAM in Bremen since 2015.
Examples of research to be taken up by IFAM include composite casting for integrating metallic structures and profiles (aluminium or steel) directly into a casting; combining low-pressure die-casting with non-metallic primary or forming processes (e.g., sheet metal forming or plastic injection moulding); or producing cast rotors for electric drives, generally a product of high-pressure die-casting.
The capabilities adopted by IFAM indicate a new range of growth possibilities for LPDC. This article first appeared in in the Foundry Magazine.
