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Science, Maths & Technology
Full mould casting (evaporative pattern)
A pattern is made from fused polystyrene beads heated in an aluminium die. Once cooled, the pattern is coated with a refractory compound, before being placed in a flask and surrounded by sand. A vacuum is applied to the flask and molten metal is poured into the pattern. Molten metal vaporises the polystyrene material as it flows into ...
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Science, Maths & Technology
Melt casting
Molten polymer is extruded, via a sprue, into the closed mould cavity formed from two parts bolted together. The mould is vented, and once polymer leaks from the vent, extrusion stops and the material is left in the mould to solidify. Bolts are removed and the component is extracted.
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Science, Maths & Technology
Monomer casting
A non-pressurised casting process using a controlled chemical reaction of polymer materials. The monomer is mixed with an initiator (catalyst), before pouring into the mould. Whilst the mixture is curing inside the mould, polymerisation takes place. Once cooled, the component is removed from the mould.
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Society, Politics & Law
Syria, Spitsbergen and Seeds
How are the civil war in Syria, the remote Norwegian island of Spitsbergen, and the future of the world’s food supplies connected?
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Science, Maths & Technology
Reaction injection moulding (RIM) and Reinforced reaction injection moulding (RRIM)
In reaction injection moulding, two types of monomers are mixed together before being injected into a mould, where they polymerise to form the plastic component. In reinforced reaction injection molding, reinforcing agents are added to the monomer mixture.
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Science, Maths & Technology
Transfer moulding
Similar to compression moulding, however, the polymer material is not placed directly into the die, but is often pre-heated before being loaded into a separate heated pot chamber situated above the die. A hydraulic plunger (ram) forces the polymer into the die cavity via a sprue. When cured, the moulded component is released using ejector pins.
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Science, Maths & Technology
Rotational moulding (Rotational or rotary casting)
A low pressure and high-temperature process for moulding hollow plastic components. Three separately rotating ‘arms’, with moulds connected to each, revolve bi-directionally around their axes. One arm is for loading and unloading of moulds, another arm is rotating within an oven, and the third arm holds a cooling chamber. The mould is opened to ...
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Science, Maths & Technology
Compression moulding
A preheated pellet of thermoset plastic is placed into the bottom half of a heated die. The top half of the die (punch) compresses the molten plastic into the shape of the die. After curing under heat and pressure, the moulded component is ejected.
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Science, Maths & Technology
Squeeze casting and squeeze forming
Molten metal is poured into the bottom half of a pre-heated die cavity. As the metal starts to solidify, the top half of the die (punch) is pressed into the bottom half and held in position until the casting has solidified. The cast component is then ejected.
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Science, Maths & Technology
Hyperforge process
A process which combines casting and forging to give components with mechanical properties comparable with forged materials. Uses retained heat from casting process.
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Science, Maths & Technology
Pore-free die casting (active atmosphere casting)
Porosity is almost eliminated by the injection of an ‘active gas’ into the die cavity, prior to molten metal being piston forced into the cavity at high pressure. The gas combines chemically with the metal to form a finely dispersed solid casting.
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Science, Maths & Technology
How can scientists fight the tide of "fake news"?
"Fake news" is as much a problem for scientists as politicians. Crispin Maslog calls for an end to propaganda dressed up in lab coats.