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Extrusion of Powders article icon

Science, Maths & Technology 

Extrusion of Powders

Hydrostatic compressive stresses and shear forces act on the powders. In hot extrusion, powder mixture is pre-compacted (‘canned’) by heat compression until all air has been removed. The sealed can is then rammed by a punch, until it adopts the shape of the die. Compacting pressure causes long sections of material to extrude from a small opening in the base of the die. In cold extrusion, metal powder is compressed directly into the die, causing sections of metal to extrude from the small hole in the die base.

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Cold isostatic pressing article icon

Science, Maths & Technology 

Cold isostatic pressing

Material in powder form is sealed into a flexible mould (or bag) situated inside a pressure vessel. Hydrostatic pressure is applied to the outside of the mould, until the powder molecules inside have bonded sufficiently. Subsequent finishing processes may be required.

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Pressureless sintering article icon

Science, Maths & Technology 

Pressureless sintering

A process where loose metal powders are poured into a metal die and vibrated until loosely compacted. When filled, the die is placed inside a furnace and sintered.

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Hot isostatic pressing (HIP) article icon

Science, Maths & Technology 

Hot isostatic pressing (HIP)

High temperature and pressure are applied simultaneously to pre-cast or sintered components. The addition of argon gas to the furnace helps to apply isostatic pressure to the component/s. The pressure and heat help to fill any pores on the surface of the component, thus optimising material properties and density.

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Cold Pressing and Sintering of Powders article icon

Science, Maths & Technology 

Cold Pressing and Sintering of Powders

A blend of powders is fed into a closed die, where upper and lower punches compact the powder using enough pressure to bind the powder particles together. The formed component is ejected from the die and heated at low temperature to burn off any residual lubricant. The component then moves to a protected environment where it is sintered before cooling.

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Powder Forging / Hot pressing article icon

Science, Maths & Technology 

Powder Forging / Hot pressing

A custom blended mix of powders is poured into a cavity mould, and compacted under pressure into a ‘preform’. The preform is heated to forging temperature then rapidly transferred into a forging press, where it is hot pressed into the final cast shape.

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Slip-casting article icon

Science, Maths & Technology 

Slip-casting

The casting slip is a suspension of fine particles in a liquid medium. Slip is poured into a permeable mould, where liquid is drawn out of the slip, via a capillary action. A layer of solid slip (‘clay’) remains adhered to the walls of the mould. Once the required wall thickness of the casting has been achieved, the residue liquid is drained out of the mould. Once dry, the casting is removed from the mould.

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CLA – Hitchiner process article icon

Science, Maths & Technology 

CLA – Hitchiner process

A vacuum is applied to a hollow investment mould sealed within a chamber, causing molten metal to rise upwards into the hollow. The vacuum is released when the metal has solidified. Chandler-Lamb were the originators, and Hitchiner is the company.

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