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either PU or TPU. Up to 90% of the footwear produced in the
world, however, still uses more traditional construction with
flat lasting and cement sole attaching by far the most
popular. Here it is more difficult to make the major labour
savings needed to make Western footwear manufacture truly
cost effective.
So, where could you save money? Modern NC-controlled
lasting machines such as those supplied by Cerim and Molina
e Bianchi have probably already reached the limit of their
development in terms of both what they can do and their
output. They can also be robotically linked to downstream
operations such that only one operator is needed to load the
pulling and lasting machine at the beginning of the sequence.
There is clearly little room for improvement here.
As we saw in
World Footwear
May/June issue, automatic
roughing and cementing machines are also available that
can again be robotically linked and are therefore extremely
time and labour efficient. When Desma was asked by
customers to look at this area, it came up with two solutions.
One is the Laser Cell as already mentioned and the other is to
lower the actual material cost of the cementing operation
and, central to this, is the Sole Cell.
This can be used as a stand-alone fixture or combined into
an automated production line. Soles fed in one end emerge
prepared and cemented at the other ready for activation and
sole attaching. Adhesive is applied by spray with total
accuracy and maximum economy. It can also apply all types
of adhesive including reactive hot melt and this is where
some real savings can be made. Desma says that using a Sole
Cell in conjunction with a reactive hot melt adhesive
produces 18% more output per person than is possible with
alternative systems.
Experience has shown that a simple ribbon around the
periphery of the sole provides the required bond strength
with a minimum usage of adhesive. It is also fast and a
Continental size 43 (UK size 8) sole can be treated in less
than eight seconds and needs only around 1.5 grams of hot
melt adhesive. Combined to a laser treated lasted margin
which, depending on the upper material involved, will at the
most only need priming, there are substantial savings to be
made. A conventional brush-applied water-based adhesive
on the other hand will need anything between 10 and 15
grams of adhesive per shoe.
TURNING FULL CIRCLE
The concepts we have looked at here are not totally new
but they have been carefully refined, such that the almost
entirely automated shoe production line is no longer a pipe
dream. There have however been relatively few takers so far,
other than one or two highly specialist manufacturers,
prepared to invest the substantial capital required as, up to
now, there has been no shortage of suitable low cost
suppliers in Asia. But, as remarked at the beginning of the
article, we live in interesting times. We also live in potentially
exciting ones as the current economic problems may well
provide the impetus for a change of direction.
Christian Decker goes on to say that: “The calls are
becoming more frequent from the conventional footwear
sector. They know that manual production often brings many
challenges, especially in quality and want to follow the
automation trend. The challenge has been finding
appropriate automation methods to fit into their current
production schemes.” The fact that machinery manufacturers
have been able to combine the strengths of electronic NC
control with sophisticated engineering may well have
sounded the death knell for the traditional labour force
everywhere and, with it, the inherent advantages of low cost
economies. On a more level automated global playing field,
could the industry be about to turn full circle and Western
countries bring footwear manufacture back home?
24
WORLD FOOTWEAR | SEPTEMBER/OCTOBER 2012
The Sole Cell automatically prepares and cements soles ready for
reactivation and attaching.
CREDIT: KLÖCKNER DESMA