The Conklad Process

In the 1980’s BWE pioneered the development of cladding and sheathing using the Conform continuous extrusion method. This work led to the introduction of Conklad, which has become the industry standard for many applications.

Cores must be processed in a straight line so that the radial extrusion format is replaced by a tangential system as shown in the diagram right. This arrangement allows a core material to pass through the die chamber so that the extrusion can be formed around it.

The Conklad process has two formats - direct cladding on hard cores and indirect sheathing of soft cores.

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.

There are three basic variants of the Conklad Process:

• High Pressure Direct Cladding - where the core material is directly exposed to the extrusion pressure. This method is used where a measurable bond (diffusion bond) is required between the core and the cladding material. Usually the core material is heated in an inert atmosphere immediately before it enters the Conklad machine. An example of High Pressure Direct Cladding is A.S. Wire.

• Low Pressure Direct Cladding - where the core material comes into contact with the cladding material but is protected from the full extrusion pressure. This method is used where the core material is not strong enough to withstand the extrusion pressure, e.g. cladding copper wire with aluminium.

• Indirect Cladding or Sheathing - where the core material is temperature sensitive or it is not desirable that comes into contact with the cladding material. In this case, the tube is extruded oversize and subsequently drawn down in line to be a close or loose fit on the core as required.