Hallo panel joinery

Timber construction | Prefabrication
Hallo panel joinery
CNC precision goes two-dimensional
Already established as in indispensable technology for rafters and purlins,
CNC joinery has now moved on to embrace the world of panel
processing. The company Witholz based in the Southwest of Germany
demonstrates what it has already managed to achieve using ultra-high
technology – including curved panel cuts or mitred three-layer panels.
Although CNC joinery has long since
become integral to the processing of
glulam, structural timber and solid
construction timber, the majority of
engineered wood panels are still manually
cut to size.
Not at Witholz based in Ühlingen-Birkendorf
in Southern Germany. As a timber dealer
with its own integrated joinery centre,
Witholz is supplying an ever growing
number of timber construction firms with
more than just bar-shaped joined timber
construction elements. The Witholz delivery
truck also transports three-layer panels cut
precisely to the millimetre, OSB or even
minerally bonded materials to customers,
making the company a true pioneer in its
field. Panel joinery is still in its infancy, with
only a handful of timber processing firms
aware of what can be achieved using the
latest equipment.
Process identical to bar-shaped joinery
The process sequence used for panel
joinery corresponds precisely to that used
for solid construction timber, frame timbers
or glulam. The CAD data is generally
speaking already available. The 3D plan is
transmitted to Witholz, where Matthias
Böhler is in charge of production engineering. The design drawing is translated into
machine language, including a cutting
waste optimization process known in the
trade as nesting. By calculating the
optimum arrangement of individual parts
on the raw panel measuring up to 2.5 by
6 metres, cutting waste can be reduced to
a minimum. Böhler estimates that around
20% less waste is produced compared to
manual joinery.
Cutting curved elements
Based on the supplied data, the Witholz
employees prepare the panels. Using
gentle-action vacuum cranes, the raw
panels are hoisted onto the processing
machine, the SPM 2 from Hundegger
based in Hawangen, Germany. This
processing centre encompasses circular
saws, end mills and drilling units. The
panels which emerge can take a whole
range of different forms: acute-angled OSB
triangular boards with cut-outs for purlins,
mitred three-layer panels or even curved
elements. To ensure clarity on the building
site, the individual parts are marked using
scribers or inkjet printers. If required, the
panels can also be primed or painted.
Another key feature is packet formation.
The panels have to be stacked in the
correct sequence to ensure their efficient
processing in the workshop or on the
building site. In many cases, all the panels
required for a particular storey of the
building or a particular component are
grouped to form a packet. During our
reporting visit to the factory, for instance,
42 mm thick three-layer panel elements for
a canopy were just being prepared for
dispatch.
Witholz takes care of regional logistics
using its own vehicle fleet. Otherwise,
finished goods are dispatched by truck to
the customer. Panels joined in ÜhlingenBirkendorf have been used for such
prestigious projects as the floating stage in
Bregenz or the X–wo?–X climbing wall.
When it comes to freeform joinery in
particular, Witholz is opening up whole new
possibilities.
CEO Jan Dreher and technician Matthias Böhler
(left to right) in the joinery hall
Demonstrating the features of the 3D drawing
system, Bühler uses the example of an outsized
walkable coffee cup. The convex and round
elements were produced on the SPM 2 in just a
few minutes – precisely to the millimetre. If a
carpenter had been required to produce this,
the work involved, the number of jigsaw blades
required and (presumably) the aggravation of
this laborious task would have been enormous.
Example number two: Witholz was just
producing 136 sq. metres of three-layer panels
for a property in Lenzerhaide. The majority of
these were mitred to an angle of 45°, and visibly
assembled. This type of assignment is only
possible with CNC automation. “No timber
construction firm would have the staff to cope
with this type of quantity”, argues Witholz CEO
Jan Dreher.
One week from order placement to delivery
Witholz keeps a stock of 8000 sq. metres of
timber and engineered timber materials. This
allows it to respond rapidly to incoming orders.
As a rule, it takes just one week from receiving
an order to delivery to the factory or building
site.
In summary, there is no doubt that the CNC
joinery is making an entrance into the world of
panel processing, as modern machinery permits
the same degree of convenience, flexibility and
quality we have become used to seeing with
solid construction timber and glulam.
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The starting point for panel joinery is a three-dimensional planning file (1). The individual parts are calculated from a cutting waste-optimized
production pattern (2). The walkable coffee cup and particularly the handle demonstrate that even radius cuts are easily achievable.