Working Metals

Depending on the application, the process used to work a metal may vary. Common processes include: Casting Forging / Pressing Fabricating Extruding Wasting method

Working Metal CASTING Is a process that fills a shaped mould or vessel with molten metal. When the cooling process has finished and the metal solidified the shape is removed from the mould. CASTING TECHNIQUES INCLUDE: Die casting Permanent mould casting Sand mould casting Centrifugal casting Continuous casting The type of method used depends on the shape of the object being cast and the metal used. Cast metals are not ductile or tough and need to be stressed relieved or heat treated to make them more machineable or serviceable

Working Metal FORGING / PRESSING Is a process that compresses a metal (usually heated to high temperatures) between shaped surfaces called dies. Drop forge hammers use rapid blows which causes grain deformation on the surface layers. Slower compression using a forging press allows the deformation to penetrate deeper This grain deformation improves the physical properties of metal. The result being parts having a higher strength to weight ratio and which are tougher and more ductile.

Working Metal FABRICATING Casting and forging are processes that produce a component from a single piece. Fabrication is a process that produces a component from a number of pieces that are joined together. Fabrication has the benefits of: Using a combination of materials with different properties Weight and material savings in large castings (minimal X sectional area required smaller) Dimensional size can be increased if material size is insufficient (joining 2 x 6mm plate to form 12mm plate) Waste associated with wasting techniques (turning/milling) reduced

Working Metals EXTRUDING Is a process that forces material through an opening at one end of a container. The shape of the opening determines the shape of the extruded metal Extrusion can be a DIRECT or INDIRECT process ADVANTAGES: Complex shapes eg tubes Good surface finish Very accurate Billet at final shape DISADVANTAGE: Dedicated tooling

Working Metals Wasting Method This is the most common method to work materials. A range processes such at milling turning, drilling, grinding or filing remove waste/unwanted material to produce the desired shape. ADVANTAGES: Complex shapes can be achieved Suits mass production Very accurate Applicable to a range of metals DISADVANTAGES: Large quantities of raw material wasted unless in can be recycled or reused. Some initial machine set ups expensive