Metal Shaping Techniques
February 19, 2019
Metal shaping, also known as metal forming, is the process of shaping metal parts and items through mechanical deformation. A piece of metal is reshaped without adding or removing material, so the mass remains unchanged. There are several different techniques used to shape metal which depend on the type of metal and the object you want to shape it into. We have listed the most common industrial processes below.
Bending is a process used to make objects with angles. It produces V-shapes, U-shapes, channel shapes on a straight axis and is most commonly used for sheet metal. Specialised machine presses are used to do this kind of metal shaping. Bending needs to overcome tensile and compressive stresses. Residual stresses will sometimes cause the metal to spring back to its original position, so the sheet has to be overbent to achieve the correct angle.
Forging is a process to shape metal using localised compressive forces. The blows are delivered with a hammer or die. Forging has different types named for what the temperature is when the metal is being shaped; cold forging, warm forging or hot forging. Forging at a higher temperature increases the plasticity of the material and reduces the forces needed to work it. The drop forging process has a hammer repeatedly dropped onto a workpiece to deform it to the shape of a die. This type of metal shaping can be done to close tolerances, so little finishing is needed. Forging is a metal shaping technique that has taken place for millennia, and traditional products made from the process included kitchenware, hardware and hand tools. Following the Industrial Revolution, forged metal was used in machines and mechanisms.
The rolling process is where a piece of metal is passed through rollers to reduce its thickness and make it even. Rolling can be done hot or cold and is mainly used for iron and steel, along with brass, copper and aluminium. The different rolling processes include roll bending, where a cylindrical shape is produced from sheet metal. Rolling is the continuous bending of a long strip of metal, usually coiled steel, as it is passed through sets of rolls. Flat rolling is the most basic process, where the material is passed through two rollers rotating in opposite directions. The distance between the rollers is smaller than the thickness of the material, causing it to deform.
Extrusion metal shaping is the process where heated metal is pushed through a die of a required shape using a hydraulic ram. Extrusion is a process used to make long objects such as tubes and bars. The advantages of extrusion metal shaping over other processes are that it can create complex cross-sections and can work brittle materials as there are only compressive and shear stresses. The extrusion process can be continuous – producing indefinitely long material – or semi-continuous which produces several pieces. Commonly used metals for extrusion include aluminium, brass, copper, magnesium, zinc, steel, lead, tin and titanium.
Casting is the process of shaping metal by pouring it when molten into a mould. The mould will have the desired shape of the object, and the metal is poured through a channel called a sprue. The metal and mould are then cooled and the metal extracted. Casting is a metal shaping process used for complex shapes which would be difficult to make by other methods. The casting method depends on the object you are making; sand casting is a quick method for complex shapes such as car engine blocks and cylinder heads. Die casting is used when several items of the same shape need to be made. It is a fast production which produces complex and precise parts.
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