Converting considerations for flexible materials
Figure 1. Laminating, zone-coating and slitting of multiple materials.
impact the performance of the coating or of material to be slit onto each package— doesn’t matter as much, since width affects
ink. sometimes 20-50 times longer than can time only in a small way—but this can work
Surface preparation is equally impor- be achieved with traditional pancake to the advantage of a customer too, since
tant. Thorough web cleaning may be neces- rolls. This in turn benefits the econom- adding width doesn’t add much to costs.
sary, as well as surface energy modification ics of downstream operations, since each Spooling’s major converting cost advantage
by the use of corona- or plasma-treating to roll changeover represents downtime and over traditional ‘pancake’ winding is the
promote adhesion. It should be confirmed waste. One aspect to monitor in spooling much longer rewind lengths, which greatly
that any method chosen for improving the is not introducing camber (curl) into the reduce changeover time for the converter.
surface does not damage the functional- material. The spiral-winding methods can There are many ways in all converting
ity of the surface. This is also true for introduce camber, especially with metals operations to design configurations to best
the method selected for drying or curing and at the edges of the spools, but this can advantage.
the coating or ink. Many coatings used be controlled through careful design of the The second lesson spooling shows
to produce TFPV products are thermally spool configurations, tensioning systems about the economics of converting is
sensitive, and care must be taken to not and winding patterns. that the entire chain of events must be
generate too much heat during this step. The spooling example above is a nice considered. Narrowly viewed, the econom-
If contact pressure is a sensitivity for the segue into discussing the economics of ics can be deceiving; the direct converting
materials being processed, a non-contact converting operations for two reasons. costs often hide the value. For example,
method should be considered, such as First, it shows how both the incom- the direct costs of spooling can often be
curtain coating or the use of application by ing and finished configurations can affect more than totally compensated for by the
ink jet. When laminating, avoid any excess converting costs. In general, converting lowered downtime and waste associated
pressure that might produce mechanical is a service operation. Although a few with fewer changeovers in the next manu-
work to the coatings as they go through the converters will offer supply-chain manage- facturing steps.
laminating nip. If air entrainment is a con- ment (purchasing of materials and vendor Another very important economic
cern, consider the use of smaller diameter management) and a few will offer ancillary aspect is waste. Materials are often so valu-
nip rollers. manufacturing services such as assembly, able that even a small percentage of waste
Materials slit to narrow widths can be the economics of the manufacturing can outstrip the entire converting cost. A
‘spooled,’ or wound transversely on a core services, including converting, are generally great deal of attention needs to be paid to
many times wider than the slit width of driven by time rather than materials. Thus, minimizing waste. Methods include proper
the materials. This provides a more stable longer incoming and outgoing lengths configuration, converting techniques and
package and enables much longer lengths drive costs down, as does volume. Width machine design, and the use of low cost
www.globalsolartechnology.com Global Solar Technology – November/December 2008 – 19
issue_2.1.indd 19 2/22/09 9:39:58 PM
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