CPA

Lead is still said to be the ideal quenching medium for achieving a ductile pearlite structure
within the patenting process. However, the days of the lead bath are numbered, as there are
much more disadvantages coming up with this it. Environmental reasons and reasons of
industrial safety because of the hazardous fumes speak against the lead bath. But most of all
the high costs due to the preheating and energy losses, high service and maintenance efforts
as well as the high costs of the melting material which has to be replaced again and again
make the lead bath no longer up-to-date. Further arguments against the usage of the lead
bath are the very inconvenient handling in the field of operation and maintenance, the lead
dragging occurring at higher wire velocities and inappropriate scale which again can lead to
higher efforts in the following pickling and cleansing baths up to necessary frequent and
costly exchanges of the galvanic baths.

The same applies to Fluidized Bed Quenching systems. Here the main problem lies in the
inefficient quenching velocity which again leads to unsatisfactory tensile strength results. Due
to the usage of sand as abrasive heat transfer medium not only the surface of the wire but
also the interior of the furnace, especially the required sand transport piping, is affected and
becomes worn-out. Apart from that a frequent emission of sand and particulate matter can
hardly be avoided which is now and in the future in no way compatible with a high quality
manufacturing process in the field of galvanic coating, e.g. such as in the production of steel
cord and saw wire.

The days of the lead bath and the Fluidized Bed Quenching systems are numbered. The
company CPA Wire Technologies GmbH, a sister company of the control technology, MES
and galvanic control system provider CPA Computer Process Automation GmbH and leading
provider of high tech brass plating lines as well as payoff and take-up systems for the steel
cord production offers a real alternative. The company succeeded in developing a completely
new technical solution on the basis of the film boiling process with significant qualitative and
economic advantages - within the framework of a research project funded by the Republic of
Austria. This solution not only obviates the need for lead baths and fluidized bed quenching
systems but also represents a significant quality improvement of so far applied water
patenting systems.

The required quenching for the patenting process after the austenitization is carried out in a
water bath which is divided into several groups. The length of the water bath can be adjusted
manually or automatically and it is directly connected to a temperature-controlled two-stage
soaking zone. This arrangement makes it possible to reach stable microstructural
transformation results which can be qualitatively compared to lead baths, but without having
to accept their disadvantages. Due to a significantly steeper temperature profile during the
quenching period in contrast to fluidized bed systems the required tensile strengths can
easily be reached without any problems and the problematic usage of sand can be
completely omitted.

The new system of CPA (patent pending) can be used with larger wire dimensions as well as
for very small diameters in the field of the final patenting of wires.
The CPA AEOX Convection Film Cooling System with two-phase soaking furnace can be
combined with the new energy-efficient Convection and Recuperation Turbo Austenitization
furnaces of CPA which provide energy savings of up to 40% and an adjustable part load
capacity between 30 and 115% of the nominal furnace load. The CPA furnaces can also be
combined with all other furnaces offered on the market and traditional existing furnaces.