Surface World June 2019 Surface World June 2019 | Page 72

PRODUCTS & PROCESSES
New choice in Temperature Profi ling
solutions to meet the demands of the
Modern Industrial Paint Cure Market . . .
Who say’s watching paint
dry can’t be made exciting?
Benefi ts of ‘Thru-process’ Temperature
Profi ling – the value speaks for itself.
The use of ‘Thru-process’ temperature profiling in the Industrial paint
and powder market has long been established as the preferred
default method for proving quality assurance of the paint cure
process. Whether a painted automotive body shell or powder coated
aluminium extrusion, it is critical to prove that the part has been
heated correctly in the oven to achieve the desired physical and
cosmetic properties of the coating. At the coating stage, significant
investment into the product has already been made, so it is even
more critical to get the coating process correct, to avoid rework or at
worst product scrappage. Getting the cure wrong is a costly mistake
to make and the implications from a business perspective are often
far more severe than many realise. (Refer to Figure 1: Incorrect Paint
Cure - the Business Pain Points).
Obviously paint cure can be determined by many different laboratory
tests (DSC, Solvent Rub, Impact etc) but these physical tests only
provide a positive or negative result and will not give any evidence to
the potential cause of the problem. The part may be under cured but
why? Was the oven set at the wrong temperature or the line speed?
Has a burner or fan failed, if so which and where?
Figure 1: Pain Point Schematic - Business implication of getting the
Paint Cure wrong.
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Despite the fact that modern ovens now are supplied with
sophisticated control systems they are still not capable of truly giving
an accurate picture of the coating cure process.
To certify that the coated product achieves the coating suppliers cure
specification (Time @ Temperature) it is necessary to know the true
product temperature through the entire oven process. Temperature
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sensors positioned along the oven give only a snap shot of what the
oven environmental temperature is at that specific point in the oven.
IR pyrometers can provide surface temperature measurement but
require line of site so limit the areas of the product that can be
measured. As with air sensors being fixed IR sensors only give
information at that specific oven location. Referring to the product this
may, as with an Automotive car body shell, be made up of many
different materials with differing thermal conductivities (steel,
aluminium, composites) and sections of very different thickness so
thermal mass. This being the case the product temperature being
measured may need to be from many unique locations to fully
understand the cure process for the complete product. For simpler or
a mix of products possibly, the location of the product within the oven
may be critical requiring multiple products to me measured at
different positions (Product Hanging Rack Top, Middle, Bottom) to
highlight possible variations in oven temperature.
PhoenixTM Finishing system . . . customized to coating process
The PhoenixTM Finishing system has been developed to specifically
provide the complete product temperature history of the product in
the paint cure oven. The system travels directly through the oven with
the product being monitored measuring continuously product and or
oven environmental temperature from start to finish. Temperature data
collected is later converted into a temperature time graph
(Temperature profile) which is a historic record of what temperatures
the product experienced and for how long in the oven. This profile
graph will not only
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provide evidence of
whether the coating is
cured correctly, as part
of a standard QA
protocol, but provide
invaluable process data
that can be used to
further control, improve
and validate the
operation as detailed in
Table 1 and further in
the following sections.
Figure 2: PhoenixTM
Compact System
travelling through a
Powder Coating Oven
with Aluminium Extrusion
Products. (Insert Data
logger Installed in
thermal barrier shown
in main image)
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