MILLING OF WOOD MATERIALS WITH
COMPUTERIZED NUMERICALLY CONTROLLED
(CNC ) ROUTER
M.Sc. Ümmü KARAGÖZ
Kastamonu University, Faculty of Forestry, Dept.
of Forest Industrial Eng, 37100, Kastamonu
/TURKEY
ukaragoz@kastamonu.edu.tr
Preview
1
INTRODUCTION
2
MATERIAL AND METHOD
3
RESULTS AND DISCUSSION
4
CONCLUSIONS
5
2
REFERENCES
1. INTRODUCTION
 Wood is a sustainable, natural, attractive and
aesthetic product, with excellent properties of
durability, acoustic performance and fire
performance. So, it has wide range of usage.
 Wood is used in the production of some
aspects of internal and external decorative
elements by such processes as cutting,
planning, CNC milling and sanding.
 Recently, Computerized numerically controlled
(CNC) woodworking machinery that can
automatically control the movements of a
spindle and table, has been widely introduced
in wood industries for automatically cutting,
drilling and shaping.
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CNC Woodworking Machinery
History
 CNC routers were first used by the aerospace industry to
cut complex patterns out of sheets of aluminum.
 And then, by the early 80’s, this technology was used in
many types of machinery in the secondary woodworking
industry.
 New functionality and improved performance is being
developed day by day which will give CNC an ever
increasing role in the success of wood machining sector
[6].
 Lately, Cad-Cam programs also have started to improve
with development of the CNC technologies and increase the
importance of design. Woodworking sector has followed
this development in terms of both design and engineering.
Cad-Cam is the integration of the Cad (design or drafting)
process with the Cam (manufacture) of the component [7].
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M.Sc. Ümmü KARAGÖZ
CNC Woodworking Machinery
 Recently, CNC woodworking machinery has been widely introduced in
wood industries especially, in the furniture industry. CNC has been used
for the grooving, milling, patterning of furniture material …ect
 The CNC woodworking machinery is mainly
focused on the achievement of high quality;
 in term of work piece dimensional accuracy,
 surface finish, high production rate,
 less wear on the cutting tools, economy of
 machining in terms of cost saving
 and increase of the performance of the product
 with reduced environmental impact.
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M.Sc. Ümmü KARAGÖZ
The surface quality of wood machined by CNC
 The surface quality;
is one of the most specified customer requirements and the major
indicator of surface quality on machined parts is surface roughness.
 The surface roughness;
is mainly a result of various controllable or uncontrollable process
parameters.
there are a great number
of factors influencing the
machined surface
roughness
Fig 1 Effecting factors on surface roughness
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M.Sc. Ümmü KARAGÖZ
The aim of the study

The aim of the study was to investigate the machinability of
Scotch pine (Pinus sylvestris L.), Oriental beech (Fagus orientalis
Lipsky.), Uludağ fir (Abies bornmülleriana Mattf.) and Carolina
poplar (Populus canadensis) with the CNC router.

.
Also, wood samples were machined
both tangential directions and radial direction.
And then surface quality of tangential and
radial direction was compared
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M.Sc. Ümmü KARAGÖZ
MATERIAL AND METHOD
In the experiments , different species of hardwoods and
softwoods were used.
For Hardwoods;
 beech (Fagus orientalis Lipsky.),
 Carolina poplar (Populus canadensis)
For Softwoods;
 Scotch pine (Pinus sylvestris L.),
 Uludağ fir (Abies bornmülleriana Mattf.)
o Primarily, wood samples were obtained from these species
at 50x50x150 mm dimensions.
o The wood samples were conditioned in a conditioning cabin
at 20±2˚C temperatures and 70±5% relative humidity to
reach Equilibrium Moisture Content (EMC) throughout 8
weeks
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And then, the moisture contents and density of wood species were
determined according to TS 2471 [14] and TS 2472 [15]. Table 1
shown moisture and density values of wood species
Moisture
content
(%)
Density
(gr/cm³)
Oriental
beech
12,10
0,671
Carolina
poplar
11,35
0,569
Scotch pine
11,85
0,558
Uludağ fir
12,54
0,426
Species
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Processing parameters;
8 mm of diameter cutter
spindle speed 8000 rpm
feed rate 6.4 m min-1
cutting depth 4 mm
surface roughness
was measured by using a
stylus type profilometer
(Mitutoyo SJ-201).
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Surface Roughness Parameters
average roughness (Ra) , the average
distance from the profile to the mean line
over the length of assessment
Surface roughness
parameters
mean peak-to-valley height (Rz), can be
calculated from the peak-to-valley values of five
equal lengths within the profile
maximum peak-to-valley height (Rq) , the
square root of the arithmetic mean of the
squares of profile deviations from the mean
line
These parameters are characterized by ISO 4287
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M.Sc. Ümmü
KARAGÖZ
RESULTS AND DISCUSSION
Species
Tangential direction
Radial direction
Ra
Rz
Rq
Ra
Rz
Rq
Oriental
beech
5,59
31,55
7,09
5,87
34,48
7,55
Carolina
poplar
5,89
34,16
7,78
5,92
33,5
7,74
Scotch pine
5,51
33,59
7,34
6,13
35,55
7,93
Uludağ fir
6,93
38,73
8,86
6,05
34,84
7,64
Table 2 shows moisture and density values of wood species
From Table 2, it can be observed that, the surface roughness values average
roughness (Ra), mean peak-to-valley height (Rz) , maximum peak-to-valley
height (Rq) were higher in the radial direction as compared to the tangential
direction
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The surface roughness of wood species according to tangential and
radial direction
Figure 3 The surface roughness of wood species according to tangential and radial direction
According to the graph, tangential direction in the CNC milling process produces a
smoother surface when compared to a radial direction. At the end of the tests realized
with similar conditions in the literature, it was shown that the radial direction produced
rougher surfaces when compared to the tangential direction. The findings obtained in thi
study support the information given in literatures [17, 18, 19, 20].
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• The surface defects such as raised grain, fuzzy grain and
chipped grain occur in the too much moisture content of
wood species.
• In order to obtain smoother surface, moisture content
should not exceed 12% [10, 21]. When the studies in the
literature were examined, it can be stated that there was
proportional relationship both density and moisture
content with the surface roughness. The values obtained
in this study are in conformance with the values in
literatures [2, 22, 23].
•
In general, the results have shown that the hardwoods have higher
processing performance than that of softwoods. In the existing literature,
it was disclosed that the surface roughness values for the diffuse porous
woods were lower than those for the ring porous woods [24, 25, 26].
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CONCLUSION_1
 The wood surface roughness directly concerns the
final use of wood products. As the surface roughness
is most important quality characteristic, the factors
that affect surface roughness need to know and to
analyse. This factors are related to machining
parameters, wood structure properties, cutting tool
and cutting properties
 Being aware of the machining parameters , wood
properties and other factors, whether directly or
indirectly, contribute to using more efficiently
woodworking machinery that were invested a lot.
 This stduy compered to machinability of wood species
such as Scotch pine (Pinus sylvestris L.), Oriental
beech (Fagus orientalis Lipsky.), Uludağ fir (Abies
bornmülleriana Mattf.) and Carolina poplar (Populus
canadensis).
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CONCLUSION_2
 At the same machining conditions (8 mm of diameter cutter,
spindle speed 8000 rpm, feed rate 6,4 m min-1 and cutting depth 4
mm), Oriental beech has shown lower surface roughness values
and has the highest machinability performance, because of its high
density.
 Density is remarkably the factors influencing the surface
roughness.
 The surface roughness decrease with increasing density value. So
Uludağ fir. (Abies bornmülleriana Mattf.) has low density, surface
roughness values were obtained highest value in this wood
species. Also hardwoods species have shown better processing
performance than softwoods.
 In this study, the surface roughness values (Ra, Rz, Rq) were
determined to be higher in the radial direction as compared to the
tangential direction.
 As a consequence, in order to determine surface quality of
machined wood by CNC and traditional machine, the many factors
that affect on surface roughness must be analyzed separately.
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M.Sc. Ümmü KARAGÖZ
Kastamonu University, Faculty of Forestry, Dept. of Forest
Industrial Eng, 37100, Kastamonu /TURKEY
ukaragoz@kastamonu.edu.tr
THANK YOU LİSTEN TO ME
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