Baking & Snack - June 2018 - 88
Swirl finish on a stainless
steel hopper helps release
sticky bar dough.
been able to chunk it and feed it onto a belt, up the
belt elevator and into the hopper." Part of the easier
release is due to the coating on the blades; part of it,
though, also comes from their programmable rotation
back and forth.
Moving bar dough out of the equipment is one
thing, but bakers must also address the challenges
that come with getting it the next point in the process.
"The feeding of mixed materials has to be at a more
consistent rate than with other bakery products," Mr.
Schmidt said. "Too much, and you can overload the
bar formers; too little, and it starves out."
Mr. Schmidt also pointed out that storing a reserve
of dough in a hopper, as done with traditional dough,
doesn't equate in bar production. "You have to look
after a wide range of bar mixes, so dedicated transfer
equipment built for single purpose products is not acceptable," he said. "Whatever we have to contend with
for bread and roll bakeries, the needs for bar producers has been an order of magnitude - 10 times -
higher and more demanding."
Geometry can help, according to Mr. Morabito.
For example, hoppers used for traditional doughs
typically have an inverted pyramid shape, which
doesn't bode well for for a mixture for bar products.
"For sticky products, you need to build hoppers like
chimneys, straight up and down. Let gravity be your
friend and allow the dough to go directly onto a belt
or chunking blade," he said. This will avoid getting
the dough stuck on the sides and wedged into the narrowest part of the hopper.
One way to ensure that dough stays on the move, Mr.
Schmidt noted, is by designing specialized equipment
that has enough power to handle the dough. "When
you build a lot of specialized machines, you know what
88 Baking & Snack June 2018 / www.bakingandsnack.com
to expect, and by doing a few tests, you can gauge what
is required from your drive system," he said.
Oversizing the drives - the service factor or safety
factor - provides the necessary torque. "We typically
oversize motors and drive systems to increase the service factor, which helps avoid issues and failures," Mr.
Schmidt said. He suggested paying close attention to
shaft and bearing loading. "Shafts with longer overhung loads will usually have higher stress levels than
motor and gear output shafts," he said.
Remember the adage, "Less is more" ... now, throw
it out the window. Think more: more horsepower,
more gearbox size, more safety factor. "These firmer,
drier 'doughs' will add a lot of power requirements, so
you need to engineer the gearboxes to a higher, heavier-duty spec," Mr. Morabito said. On a belt, the stickiness will act like a brake, and the dough won't convey,
so oversizing a gearbox with a safety factor of 2 or
more (Topos recommends 1.25 or 1.5 on traditional
dough applications) will give it the power it needs.
Mr. Morabito advised that the safety factor doesn't
Bar inclusions can also
be fragile, so it's important
to have a transfer
system that can handle
a variety of textures.
apply when the operation is in a steady state. "It's
when things go awry - someone added too much
molasses or not enough gum so it became extra sticky
and firm - that's when the product becomes abnormal and still runs through the machinery; that's when
you can break it," he said. Designing the gearbox, belt
rollers and bearings with a safety factor will ensure
that the transfer equipment will be able to handle it.
"Or at least set off an alarm so it doesn't create damage downstream," he added.
High sugar content makes dough sticky, and that
problem increases exponentially for bar doughs. To
address this, Handtmann designed its transfer equipment with an adjustable vacuum pump. "This allows
us to vary the required power to process different
types of dough formulations from soft and fluffy to
hard and dense," Mr. Zelaya said. "For cases where
high torque is required to pump and process dough,
Handtmann offers a high-pressure extruder that can
operate at a high-pressure level to pump hard and