The CONFORM process
The use of a single revolving wheel as the driving force in an extrusion process enables the manufacture of products of unlimited length. In its simplest form the wheel has a single groove in its periphery which accepts the feedstock and transfers the material to the extrusion zone and die.
The diagram (A) shows the configuration normally used for the production of solid and hollow sections. As the product leaves the wheel in a radial direction the process is commonly referred to as radial extrusion.
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A die chamber, carrying the appropriate die , is supported in a massive shoe. The die chamber incorporates an abutment which protrudes into the wheel groove which itself carries the feedstock material. The force applied by the rotating wheel causes the feed material near the abutment to flow plastically into the die chamber and exit through the die as the final product. While the feedstock is usually in the form of rod, the process can also operate with material of any morphology provided that it can be fed into a groove of suitable size.
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The capacity and flexibility of the process is substantially increased by the use of two grooves in the wheel (diagram B). This format enables extrusions of larger cross-sectional area to be produced with standard size feed rods and at acceptable output rates. The twin groove system also allows the use of more robust tooling in the extrusion zone and creates more space to permit extrusions of high width to thickness ratio to be produced.
Improved tooling design, in twin groove configuration, particularly for hollow sections, provides effectively seamless products which can be produced at higher output speeds and tighter tolerances.
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The use of the twin groove wheel enables a further development of the process, established by BWE Ltd and called Twinex. Using a special die chamber each feed rod can be made to produce a separate product. This mode considerably increases the capacity of the machine for products with lower cross sectional area and enables a wider range of products to be efficiently extruded without changing rod sizes or wheels.
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The CONKLAD process
The greatest advance in CONFORM technology has been achieved by BWE in the application of the process for the sheathing or cladding of temperature sensitive (soft) or hard cores as they pass through the extrusion tooling.
Cores must be processed in a straight line so that the radial extrusion format is replaced by a tangential system (diagram C). The CONKLAD process has two formats - direct cladding on hard cores and indirect sheathing of soft cores. |
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Direct cladding on hard cores.
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 | High pressure cladding is used when a measurable bond (diffusion bond) is required between the core and the cladding material. The core is heated prior to the extrusion process. | |
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| Low pressure cladding is used when the material or the cross-section of the core is such that the very high pressures normally applied would cause damage to the core. | |
Indirect sheathing of soft cores.
| When the core is temperature sensitive the tube is extruded significantly oversize and immediately cooled to ambient temperature. The 'loose' sheath is usually drawn down in-line with the extruder. As the developer of this process BWE Ltd holds a basic patent for the sheathing of a temperature sensitive core where the metal extruded tube is drawn down in-line by use of the CONFORM process. | |
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