Finishing - November-December 2022

14 CORROSION PROTECTION
150 parts to be met.
To optimally integrate the cleaning system
into the existing workflow, buffer that holds
five workpiece carriers is located on the input
and on the output side. The carriers, which are
marked with a digital matrix code to ensure
seamless documentation of the cleaning
process, are fed one at a time into the
cleaning cabin via an appropriately-sized lock.
As soon as the lock is closed, the cleaning
process starts. Using a specific motion
sequence, a robot moves the cleaning unit
with jet nozzle over the valve components at a
defined distance. A sensor system
continuously monitors the consistency of the
jet. Once all parts have been cleaned, the lock
on the output side opens and the workpiece
carrier is advanced to the encapsulated
unloading area.
in order to ensure optimum adhesion and a
long-lasting coating. A wet-chemical cleaning
process was ruled out because of the high
effort, space requirements and energy
consumption associated with drying.
CO2 snow process optimally
prepares surfaces for coating
Extensive cleaning tests in the acp systems
technical center demonstrated that partial
cleaning with the quattroClean snow jet
technology achieves the cleanliness needed to
obtain an optimal coating result. The process
uses liquid carbon dioxide as a medium. CO2
is a by-product of chemical manufacturing
processes and biogas energy generation, thus
making it climate neutral.
In the cleaning process, liquid carbon
dioxide is passed through the inner ring of a
wear-free, two-component ring nozzle and
expands on exiting to form fine CO2 crystals.
This jet of snow is then bundled by a separate
jacket jet of compressed air (outer ring) and
accelerated to supersonic speed. The easy-tofocus
jet of snow and compressed air impacts
on the surface to be cleaned at a temperature
of minus 78.5°C, triggering a combination of
thermal, mechanical, sublimation and solvent
effects. The cleaning action brought about by
the interaction of these four effects removes
the dried-on mixture of machining oil and
particles in a dependable and reproducible
manner. The detached impurities are carried
away by the aerodynamic force of the jet of
compressed air and eliminated from the
cleaning cell together with the sublimated
CO2 in the gaseous phase. This reliably
prevents parts from becoming
recontaminated.
Tailored fully-automated
process
To clean the valve components, acp built the
fully-automated Jetcell cleaning system using
standardized modules, tailoring it to the
application and to the manufacturer’s
production conditions. The workpiece carriers
are used both for the cleaning step and for
the partial PVD coating process. Process
parameters, such as the volume flows for
compressed air and carbon dioxide, type of jet
nozzle, distance of jet away from the part,
cleaning time, as well as the motion sequence,
are appropriately adapted. This enables the
required cycle time of six minutes for cleaning
a fully-loaded workpiece carrier with around
CO2 cleaning process integrated
into measuring cell
Indexable inserts, which are manufactured
in small quantities with individual geometries
and dimensions varying between ten and
twenty five millimeters, have extremely tight
tolerances that may not exceed one to two
micrometers. To ensure this high accuracy, the
entire contour of the carbide parts is
measured at the manufacturer's after grinding.
Since impurities on the surface from
machining residues and grinding dust can
cause measurement errors, in the past the
inserts were cleaned manually at great
expense. The manufacturer wanted to
integrate this process into the automated
production line. Here, again, after cleaning
trials and defining process parameters, the
decision was made in favor of the
quattroClean technology.
In this case, a cleaning module was
integrated into the measuring cell, which is
docked directly to the grinding machine. This
solution allows the existing robot to remove
the inserts from the grinding machine via a
lock, move them in a defined short motion
sequence under the snow jet and then set
them down neatly in the measuring area. The
motion sequences, jet-cleaning times and
respective volume flows for the various
indexable inserts are all stored in the control
system as part-specific programs.
By precisely tailoring the cleaning step to
the application and cycle time specifications, as
well as being able to operate the system as a
stand-alone unit, inline and in interlinked
manufacturing environments, the Industry 4.0-
capable quattroClean snow jet technology can
play a major role when it comes to automating
and digitizing production processes. Thanks to
standardized interfaces, it is no problem to
integrate the cleaning system into higher-level
host computers and control it via these. To
ensure seamless documentation and
traceability, all process parameters are
automatically recorded and transmitted to the
host computer.
Finishing - November/December 2022