Panels & Furniture Asia May/June 2020

60 | WOOD CLINIC
May / June 2020, Issue 3 | Panels & Furniture Asia
to the louvered door design drawing and confirm the milling
cutter diameter of 6.0mm when replacing it.
- Inconsistent specifications of slats: if the multiple louver
machine is not set in place, the slats are too thin, or
the thickness is irregularly set during wide-belt sanding,
the thickness of slats will be not consistent, thus leading
to inconsistent tightness of slats of the louvered door. It is
suggested that the workers set the thickness of slats to
6.0mm after sanding, and in accordance to the specifications
on the drawings of the louvered door.
4. Slats arched
When the milling cutter of the automatic slotting machine is
blunt, the depth of milling slot is at critical point, or the slat
arch is too tight because of the excessive length tolerance of
slats... All of these will cause the slats to arch (Figure 2). It is
suggested to check that the milling cutter of the automatic
slotting machine is sharp and the milling slot is deep enough.
The length of slat must be strictly controlled when sawing, and
both ends should be at right angles.
5. Doorpost damaged
There are three main reasons why the doorpost is often damaged
during assembling the louvered door.
- Improper setting of automatic slotting machine: when the
milling slot is too short, the milling slots will become
damaged during the assembling when dozens of slats are
pressed into the milling slot of the doorpost at the same
time. It is recommended to thoroughly check the accuracy of
the automatic slotting machine and train the worker so
that they are skilled in setting milling slots according to the
specifications on the drawings.
- Improper specifications of slats: the thickness and width
tolerance of slats is too large. Suppose an 80-inch-high
door requires about 64 slats. If the slat is 0.30mm larger
than the milling slot, the door post will crack during slotting. It
is suggested to strictly control the thickness and width of slats
according to the specifications on the drawing.
- Improper chamfering of slats: when chamfering on one side
or at one end not in place, it will be stuck in the milling slot
edge when pressing during the doorpost installation,
resulting in crushed milling slots. It is recommended to
check the chamfering equipment and reset it to ensure that
the chamfering at both ends of the slats is even and in place.
- Improper setting of assembly press: in the cases where the
assembly press mold is not set accurately enough, the centre
lines of the louvered door components are not on the same
horizontal surface, or the centre lines of the louvered
door posts, the transom’s log mortise and the milling slot
center line are not aligned in the most accurate positions,
the main implication will be a crushed milling slot or
distorted louvered door during the assembling and pressing
process. It is recommended to do a thorough check of the
setting of the mould at the assembly press, confirm that the
setting is in place, and strictly control the positions of the
log mortises of the louvered door post and the transom, as
well as the milling slot centre line.
(II) After assembly, the louvered doors need many rounds of
repairs by hand sanding, affecting production efficiency. Some
suggestions to improve the process are provided as follows:
1. Quality control of materials
- The grade of wood purchased should meet the requirements
of the louvered door order. Wood with too many defects such
as knots, wormholes and discoloration are not acceptable.
When purchasing wood, such defects should be avoided as
much as possible to reduce the screening and repair work,
thus indirectly improving the production efficiency.
2. Four-side planer
- When using the four-sided planer for processing doorposts
and louvered door transoms, the linear speed of the planer
should be maintained at 10 m/min (planer tool mark
12/inch) according to the specifications of the louvered
door design drawings. The planing tool should be kept sharp
to reduce fuzzing and roughness on the surface, thus
reducing the need for puttying and hand sanding after
processing the door components.
Figure 1: After spraying white paint on the louvered door, it can be
clearly seen that there is an obvious loose seam between the slat and
the milling slot
3. Multiple louver machine
- Slats should be produced according to the specifications
of the louvered door design drawing. The arcs on both sides
of the slat should be kept symmetrical (r = 6.0mm).
Linear speed should be kept at 8 m/min and the sharpness
of the planing tool should be maintained to reduce fuzzing
and roughness on the surface, thus reducing the need for
puttying and hand sanding afterwards.