Joint investigation analysis

Report on the Joint Investigation
Analysis for the Development of
Technology Package for Bamboo
Boards (Bamboo Laminates)

Sponsored by
TIFAC

Prepared by
IPIRTI Bangalore

1


Introduction
Development of panel products based on bamboo strip are gaining importance as these
panel products reassemble wood when used in a particular fashion as in parallel
laminates. These laminates will have superior physical mechanical properties and are
suitable for structural and specialized application. More over requirement of resin
adhesives is expected to be lower compared to bamboo mat based composites and
therefore making the products cost effective which are considered to be ideal for
alternates to wood and plywood for several end use applications.
IPIRTI has developed bamboo laminates, which can be a good substitute for sawn wood
in many applications particularly in furniture. Bamboo laminates are durable, stable
and environment friendly. Synthetic resin adhesives like urea formaldehyde (UF resin),
Melamine Urea Formaldehyde (MUF resin) and Phenol formaldehyde (PF resins) have
been used in the investigation with modifications required for uniform bonding of the
bamboo strips.
Bamboo Laminates/boards
Bamboo laminates could replace timber in many applications such as doors and
windows, frames, partitions, furniture, flooring and some structural applications.

IPIRTI has already developed a technology for bamboo laminates that is ready for
commercialization. Critical to this aspect is the establishment of process and technology
parameters, in the form of technology packages that could be taken on for commercial
application by entrepreneurs. Bamboo needs to undergo certain processing to convert to
value added applications. To establish the process technology parameters at different
stages of conversion to boards/ laminates, after determining the anatomical, physicomechanical & chemical properties and anti-fungal treatment, an intensive exercise is
being taken up by IPIRTI, Bangalore, in a joint study with TIFAC, New Delhi.
In order to prepare a technology package encompassing the critical aspects for
processing technology in terms of properties of two species of green bamboo i.e.
Bambusa nutan and Dendrocalamus hemiltonii has been identified and obtained from
Assam. The yield of workable slabs after the primary processing operations such as
crosscutting, radial splitting, two- side and four-side plaining has been compiled. Other
operations such as starch removal & anti-fungal treatment for slivers/slats, drying &
gluing followed by hot pressing and finishing of the final product has also be
investigated.
Methodology
Under the project the following detailed investigations were carried out:
Sl
No.
1.

Activity
Study on Green bamboo

Check points
x Average usable length, diameter, wall
thickness, node protrusion
x Inter-nodal distance
x Starch, silica and lignin content
2

2.

Cross cutting

3.
4.

Radial splitting
Two/ four side plaining

5.
6.

Slivers/Slat finishing
Product Yield

7.

Resin
manufacturing,
application and hot
pressing
Testing

8.

x Moisture content
x To be cut to required length depending

on hydraulic press platen size.
x Uniformity of splits
x Machinability/amenability to
processing
x Surface straightness
x Measurements of dimensions, sizing &
sorting
x Fibre separation
x Yield / Wastage study
x Texture & smoothness of slivers
x Yield of slivers/slats from green
bamboo culms to be calculated on
weight basis
x Adhesive formulation, Assembling, Hot
pressing, Trimming & Finishing
x Product testing to evaluate mechanical
properties

The bamboo strips are boiled in preservative for 3-4 hours during which starch is
removed.
The study involves evaluating the yield of bamboo at different stages of processing
from green bamboo to final board level. The critical aspects for processing technology
are in terms of properties of green bamboo and the yield of workable slats after the
primary processing operations such as cross-cutting, radial splitting, internal knot
removing and four-side planing. Other operations such as starch removal & anti-fungal
treatment for slivers/slats, drying & gluing followed by hot pressing and finishing of
the final product have also been investigated along with testing parameters & methods
for final products i.e. bamboo laminates/boards. The study has given the yield of
products from green bamboo after harvesting.
1.

Species of bamboo used for making bamboo laminates

Two species of bamboo namely Bambusa nutan and Dendrocalamus hamltonii which are
available in plenty in North Eastern part of the country were taken for making laminate
under the present study.
Characteristics of bamboo
i). Bambusa nutan
A medium sized bamboo, culms 6-15mts in length, 5-10cm diameter, loosely clustered
straight, green, smooth and not shining. Internodes 25-25cm long and thick walled.
3


ii) Dendrocalamus hamiltonii
A large bamboo sometimes growing tall and erect or often culms at an angle or curved
downwords. Culms 12-20mtrs or upto 25 mts tall. Usually naked below, much
branches above. 10-18.5cm diameter, greyish white when young, dull green when old.
Internodes 30-50cm long wall thickness 1.2cm thick.
2.

Manufacturing process of bamboo strips and yield
The procedure for making Bamboo strips involves the following steps
a.
b.
c.
d.
e.
f.
g.
h.

i.
j.
k.
l.

Selection of bamboo
Marking to the required length
Cross cutting and external knot removing
Splitting and sizing
Internal knot removing
Boiling/steaming
Drying
Four side plaining
Sorting & Assembling
Gluing
Pressing
Trimming & plaining

Bamboo culms of larger diameter not less than 10cm and wall thickness in the range of
1 to 1.5cm were cross-cut to predetermined length in a cross cutting machine. Branches
in the nodal portion, if any, were removed by manual process and mounted on
splitting machines. The split bamboo were than mounted on knot removing and width
sizing machine so as to get rid of external bulging and to get rectangular bamboo strips
not having more than two nodes in a given length to facilitate further processing. The
bamboo strips were then immersed in boiling water in the presence of preservatives so
as to remove the starch and enhance the durability of the bamboo. These strips were
than dried to 8-10% moisture content in a hot air chamber. These strips were then
passed through the four side plainer to get bamboo strips of smooth and uniform
thickness.
Note: Selection of raw material is one of the important steps from the point of view of

reducing the wastage and getting quality strips. For these purpose bamboos with large
culms and thick walls are suitable for processing as the number of sections obtained
from each culm or more there by getting more number of strips. It is also advisable to
select straight bamboo which can be processed easily and to avoid wastage. The wall
thickness should be in the range of 12mm-15mm and having an outer diameter of more
than 90mm so that the processing will be easy and wastage is reduced. Moisture content
of bamboo is very important for processing. The moisture content of bamboo should be
in the range of 40-70 for smooth processing into strips. Otherwise dry bamboo has to be
kept under water to gain moisture before splitting.
4


The following flow-chart explains the step by step process from green bamboo culms to
board making.
Primary Processing : ( Steps for Sliver/Slat Making from Green Bamboo Culms):
Green Bamboo Culm > Cross Cutting to required length > Radial/parallel Splitting >
Internal Knot Removing & Two-side Plaining > Four-side Plaining > Slivers/Slats
Secondary Processing : (Steps for Making Board/Laminate from Slivers/Slats):
Slivers/Slats > Starch Removal & Anti-fungal Treatment > Drying > Resin Application
> Laying of Slivers/Slats > Hot Pressing & Curing > Laminates/Boards > Trimming >
Plaining/sanding.
Surface Coating: Finishing Stages
Board > Surface Sanding & Finishing > Surface Coating with melamine/ polyurethane
> Curing of Laminate > Fine Sanding > Evaluation of Surface Properties.
MATERIALS AND METHODS
Species of bamboo:
Bambusa nutans
Dendrocalamus hamiltonii
Length of Bamboo:
5 mts

No. of bamboos:
500 Nos. each obtained from Assam.
OBSERVATIONS
1.
2.
3.
4.
5.

About 30 –– 35% of bamboo had slight curvature either in the centre or
towards the end.
The curvature of bending varied from 2”” to 8””.
Internodal length varied from 35 cms –– 60cms within the bamboos.
Outer diameter varied from 55cm- 88cm within the bamboo.
Inner diameter varied from 30cm to 60cm within the bamboo.

PROCEDURE
10 samples of bamboo from each species were randomly selected and measurements
such as length, inner diameter, outer diameter, wall thickness, internodal length and the
weight of the bamboos were recorded. The process was continued for 14 batches and all
dimensions were recorded.
Table 1: Average physical data of species Dendrocalamus hamiltonii
Length
in mtrs
5.02

Outer dia Inner dia Weight in
in mm
in mm
kgs

67.89
43.19
10.5

5


Table 2: Average physical data of species Bambusa nutans
Length
in mtrs
5.0

Outer dia Inner
Weight
in mm
dia in in kgs
mm
69.35
39.83
9.03

Cross-cutting
A cross cutter is used for making a cut across the culms without development of any
additional splits on the culms and leads to drastic reduction in raw material wastage. A
Tungsten Carbide Tipped (TCT) saw is used for Cross-cutting Bamboo culms and it
needs periodic resharpening. There is a provision in the machine where the desired
length of Bamboo to be cross-cut can be preset. Safety guards are provided on the
machine to take care of the safety aspects during operation.
Since the laminate size was 1.22 mt., the bamboo was cut to 1.22mt and reweighed.
From the difference in weight the yield was calculated.

Table 3: Average yield of cross cutting
Species

B.nutans
D hamiltonii

Wt. of Time for Wt.
of
bamboo processing Processed
(kg)
(min)
bamboo
(kg)
51.76
4.5
51.7
53.3
5
52

Differe
nce in
Wt.
(kg)
0.06
1.3

%
Yield

Remarks

99.88
97.56

Yield is less if
the bamboo is
bent

The cross cut bamboos were then divided into two portions and weighed. First portion
was subjected to radial splitting and second portion was subjected to parallel splitting.
From these, few samples were drawn for density measurement, moisture content, lignin
content, starch and silica content. It is well established that the diameter and wall
thickness of the bamboo varies from top to bottom. Hence it is advisable to segregate
the bamboo as top, bottom and middle portion so that the quality of the strips and the
width of the strips can be maintained.
Splitting: The main function of this machine is to carry out splitting of Bamboo culms
using two parallel circular blades. The spacing between the two circular cutters can be
adjusted depending upon the width desired. The advantage of this machine over the
radial splitter is that somewhat uniform width splits can be obtained. This will reduce
the requirement of planning.

6


Table 4: Average data for splitting of bamboo
Species

B. Nutans
D hamiltonii

Wt.
Of
bamb
oo
(kg)
51.76
48.8

D hamiltonii

58.1

Type of Time taken
splitting for
processing
each cross
cut section
Radial
3min 5 secs
Hand
split
Parallel
1hr 10 min

B.nutans
D hamiltonii

44.4
46.6

Parallel
Parallel

1hr
45 min

Wt. of Differ
splits ence
in Wt.

%
Yield

Remarks

51.7
48.2

0.06
0.6

99.88
98.77

-

36.8

21.3

63.33

Bamboo
was bent

24.3
26.3

20.1
20.3

54.73
56.44

Bamboo
was bent

OBSERVATIONS
-

-

Radial splitting is faster and wastage is also less, but the split
width is only 14-16 mm. If the specification for the purchase of
bamboo is followed meticulously, then the width of the
bamboo and the no. of blades can be changed without any
problems. Parallel splitting is time consuming and a number
of machines will be required for production line
A lot of dust is formed during splitting. This is hazardous to

operators. Installation of a dust collector should be done
Width of the parallel splitting bamboos are in the range of 2225 mm which are quiet useful for horizontal laminates
Though parallel splitting in slower, the cost of a parallel
splitter is much less than a radial splitter and with a trained
operator the quality of slivers is more uniform in parallel
splitting. Also, the wastage & jamming of machinery at the
planing stage is less

The splits are then dressed with a hatchet, so that it can fit into knot removing machine.
This is not a mandatory operation during processing of bamboo. Since the diameter of
the bamboo was less than 85mm, protrusion of knots was higher than expected. Hence
hatchet was used for dressing the bamboo. This process is labour oriented and
production depends on skill of the worker. Strip is passed through knot removal and
width sizing machines.
Bamboo width sizing, knot removing and plaining: The splits are two sized planed with
the help of rotary cutters in this machine.

7


Table 5: Average data on two side planing
Species

B. Nutans
D hamiltonii

Wt.
of
strips
32.0

48.2

Time taken
for
processing
50 min
1hr

Wt. of
final
strips
23.4
38.0

Differe
nce in
Wt.
10.6
10.2

%
Yield

Remarks

73.12
78.8

OBSERVATIONS
- Strips having bigger knots have to be dressed properly to fit into the machine.

-Machine breaks down often. Modification of the machine to suit Indian
bamboo is most essential
-The blades has to be sharpened once in 6-8 hours depending on the
species of bamboo or otherwise it will affect the smoothness of the strips
Starch Removal & Preservative Treatment
The rough planed strips are boiled in boiling vat. Chemicals like Sodium
Pentachlorophenate, Boric acid-Borax mixture are added to water in the vat as
preservatives . The concentration of the chemicals are 1% NaPCP, 1.5% Boric acid and
1.5% Borax. Normally, bleaching is not carried out during boiling since, hydrogen
peroxide will have a violent reaction. Hence it is advisable to bleach the strips either
before boiling or the laminates can be bleached.
The colour of the strips can be changed by steaming the strips in a pressure tank, which
is heated by steam at 5-6 kg/cm2 for 2-4 hours. The intensity of the colour depends on
the temperature and the time. The higher the temperature and longer the time the
darker will be the colour.
After boiling and steaming the strips has to be dried in hot air chamber at 80r 2oC to a
moisture content of 8-10%. If the strips are not dried properly there are chances for
fungal attack. After drying the strips can be passed through four side plaining machine
which is equipped with four side and face cutters of which two cutters horizontal and
two are vertical so that it can plain four surfaces of each strip at the same time to a
predetermined dimension. The plain strips may have some defects like blue stains,
sawing marks, reining, dents and ripples. Hence it should be checked and graded
accordingly. The present facility available at IPIRTI is only a oven and not a
dehumidification chamber as already pointed out in the earlier line the hot air chamber
can be made use for drying of the strips.
Table 6: Average data for drying of strips
Batch Species
Wt. of Time taken
No.
strips for drying

BO2 B. Nutans
23.4
3 hr 40 min
BO3 D hamiltonii 38
4hr

Wt. of final Difference
strips
in Wt.
17.7
10.6
29.6
10.2

%
Yield
75.64
77.89
8


Bamboo four side plaining machine: Planing of all four sides of Bamboo strips is done
by this machine. The width and thickness of the strips can be set in this machine and
smooth surfaces and uniform size for all strips are thereby obtained.
Table 7: Average data for four side planing
Species
Wt.
Time taken Wt. of
of
for drying final

strips (min)
strips
(kg)
(kg)
D hamiltonii 29.6
40
12.8
B.nutans
11.8
35
5.1

Thickness
(mm)

Difference
in Wt.
(kg)

%
Yield

4.22
3mm

16.8
6.7

43.24
43.22

OBSERVATIONS
i. Since the diameter of bamboo is less, the strips are more concave
in nature. To obtain a rectangular strip, more material has to be
removed. Thus the thickness of strips obtained does not exceed 4
mm
ii. If four side plaining is done before drying, due to high moisture
content, there are chances of warping of strips. More over fibre
rising in the strips will be predominant
iii. Dust/splinters coming out of the wet bamboo will block the
dust extractor and causes stoppage of the machine
iv. On the other hand, the boiled and dried bamboos are easy to
operate and quick in processing. Fine dust comes out of the
dried bamboo will be easy to suck from the dust extractor.
Table 8: Analytical data on Bamboo
Lignin
content
%
27.49

Silica
Content
%
1.7

Remarks

588.72

Starch

content
%
2.22

12-14

-

0

18.5

-

Starch
gets
removed

43.51

764

2.7

29.3

1.7

0

17.5

--

Sl
No.

Species

Moisture
content%

Density
Kg/m3

1.

B.nutans
Before
boiling
B.nutans
After boiling

70.72

D hamiltonii
Before
boiling
D hamiltonii
After boiling

2.

3.

4.

12-14

Starch
gets
removed

9


Silica content after boiling is not applicable as the epidermal layer is removed after strip
making and then put for boiling. When analysed it indicated that silica is mainly present in
the epidermal layer.
Resin formulations and its processing
Urea formaldehyde resin
Liquid urea formaldehyde resin was manufactured in the resin kettle by reacting urea
and formaldehyde in the mole ratio of 1:1.5. Reaction was carried out initially at pH 7.5
–– 8.0 at a temperature of 90 –– 950C for a period of 90 minutes followed by reduction of
pH to 5.0 –– 5.5 and continuing the condensation at 90 –– 950C till the desired water
tolerance of the resin was obtained. pH of the resin was finally adjusted to 7.5 and
cooled to room temperature.
The resin manufactured had the following properties.
1.
2.

3.

Flow time –– 22 seconds at 250C when measured in B-4 flow cup of IS:3944
Water tolerance –– 1:3.0 at 250C
Solid content –– 48 per cent (appox.)

Urea melamine formaldehyde
Liquid Urea melamine formaldehyde (UMF) resin was manufactured by reacting Urea
melamine and formaldehyde in the mole ratio of 1: 0.75 : 0.75. Reaction was carried out
initially at ph 8.0 at temperature 90r20C for a period of 50-60 minutes till the water
tolerance of the resin is obtained .pH of the resin is finally adjusted to 7.5-8 and cooled
to room temperature.
The resin manufactured had the following properties.
1. Flow time –– 18 seconds at 250C when measured in B-4 flow cup of IS:3944
2. Water tolerance –– 1:2.5 at 250C
3. Solid content –– 52 per cent ( appox. )
Phenol formaldehyde resin
Liquid phenol formaldehyde was manufactured in the resin kettle by reacting phenol
and formaldehyde in the mole ratio of 1:2.1. The reactants were heated up to 600C. Due
to exo-thermicity, temperature goes up to 90r20C automatically. When the temperature
is stabilized it is lowered by cooling and the resin was condensed at 85r20C till the flow
time when measured in B4 cup of IS:3944 is 15-16 sec in hot condition. The resin is then
cooled to room temperature and discharged.
The resin manufactured had the following properties.
1. Flow time –– 27r5 seconds at 250C when measured in B4 flow cup of IS: 3944
2. Water tolerance –– 1:10-12 at 250C
3. Solid content –– 48-50 per cent
10

Adhesive formulation
The liquid resins manufacture above was compounded with 10 per cent filler/extender.
In case of UF resin 0.5 percent Ammonium chloride hardener (solid content basis) and
2.5 percent melamine fortifier was added before applying on to the strips.
Sorting of bamboo strips
Bamboo strips plained with 4 side moulder were checked for moisture content. The MC
at this stage should be 8 to 10 per cent. In case any strip was found to have higher
moisture content, it is sent for redrying. Strips were then sorted manually depending on
their quality and colour. Strips having no visual defects and uniform colour were taken
separately. Visual defects considered are non uniformity in thickness and width, strips
with splinters, decay, burn, hole, wide variation in colour etc. Strips having no defects
are used for top and bottom layer in horizontal laminates. Defective strips are used as
core layers in the horizontal laminates and vertical laminates. However strips with
defects beyond certain limits are rejected. The criteria of rejections are as follows.
Thickness variation : above 10 %
Decay/burn: more than 5 cms. Long and 1 cm wide. Some times when bamboo is stored
in a dry place without drying then it is prone to attack by fungus. Hence black spots
will be seen predominantly on the strips. These black spots are termed as burn.
Rejected strips can be used after elimination of defective parts. The small length strips
can form the mid core of vertical/horizontal laminates.
Pre assembly
Sorted and selected strips are taken separately and assembled for laminates of definite
width and thickness. During the present study the laminates of following dimensions
were made.
Length

Width

Thickness

Vertical Laminate :

1.22M

10-12 cms.

18-19 mms

Horizontal Laminate:

1.22 M

10-15 cms.

18-20 mm

Strips were pre assembled with chosen strips for face and core and bundled together.
Bundles are then taken for gluing.
Gluing of strips:
Under the present study gluing of strips were done by brushing with hand. In the case
of UF bonded laminates, strips were assembled immediately and taken for hot pressing.
For PF and UMF bonded laminates glue coated strips were allowed for open assembly
to obtain requisite moisture content of the glued strips. The desired MC of the glued
11


strips before hot pressing are 18-20 % for MUF resin and 16-18 % for PF resin. The
consumption of the glue per sq ft of laminate works out to 35-40 gms.
Note : Gluing of strips manually by brushing is laborious and time consuming. Better
means of gluing the strips is passing through a glue spreader. A glue spreader with 30

cms rubber roller will be sufficient for this purpose.
Table 9: Data on Average Glue Consumption of bamboo laminates
Species

B nutans
D hamiltonii
B nutans
B nutans
D hamiltonii

No of
strips
glued
22
22
22
22
22

Width
(mm)
21
21
18
18
18

Thickness
of strips
(mm)

4.00
4.00
3.5
3.5
3.5

Glue
consumption
(gms)
250
250
200
250
250

Type of Type
of
Resin
Laminates
MUF
MUF
PF
UF
UF

Vertical
Vertical
Vertical
Vertical
Vertical

Assembling and hot pressing
Once the glued bamboo strips are ready they are taken for assembly. The strips which
were pre assembled for a particular laminate are again reassembled and tied together (
at least in 3 places ) along the length. The assembly is covered with BOPP film which act
as releasing material. The assembly is now ready for hot pressing. A number similar
assemblies are made ready together depending on the capacity of the hot press.
Hot press used for pressing bamboo laminates is a simple hydraulic press with flat
platens and arrangement for applying pressure vertically. The hot press is equipped
with the following additional facilities to make the press suitable for pressing bamboo
laminates.
i)
Arrangement for applying pressure horizontally.
ii)
There are dividers placed on the platen. The dividers are steel bars of
rectangular shape having 5 cm width and thickness equal to the
thickness of the laminates to be made.
For the present study dividers of 19 mm thick were used. The hot press platens were
heated with steam. Temperature of the platens was kept at 105 –– 1100C for UF resin, 115
–– 1200C for MUF resin and 140 –– 1450C for PF resin. Hot press pressure varying from
10-14 kg/cm2 with side pressure 2.5 kg/cm2, vertical pressure for vertical laminates. 10 14kg/cm2 vertical pressure and 2.5 kg/cm2 side pressure for horizontal laminates were
applied. Hot press time was 12 minutes for 18 mm thick laminates. If the side pressure
is more than the required then there are chances of buckling of the finished product and
the rejection rate will be more.
Planing and finishing of laminates with various surface coating agents

12


Laminates manufactured in the pilot plant were on both ends to obtain smooth, square

ends. The laminates were then plained in a plaining machine to get smooth surface.
Sanding and surface coating of the product need to be carried out to obtain the finished
product.
Testing of bamboo laminates
10 samples of vertical laminates were tested for block shear strength, MOR, MOE, screw
withdrawal strength, compression strength and abrasion resistance properties.
Results and Discussions
The outer diameter of bamboo is in the range of 60-70 mm, which is very much less for
parallel splitting. The minimum diameter required for splits of uniform width with
maximum yield should be in the range of 85 to 95 mm. The weight of the bamboo also
varies considerably; this may be due to uneven moisture content percentage of moisture
varied from one bamboo to other and also it may be due to different age groups.
Selection of bamboo for making laminates is one of the important criteria from the point
of view of not only quality but also to make it cost effective. The results of the cross
cutting operation indicate that it is a simple and low time consuming step with
negligible wastage. Splitting can be done in three ways i.e. [1] Radial splitting, [2]
Parallel splitting and [3] Hand splitting. From the table it is clear that parallel splitting
is more time consuming and 1 percentage of wastage is also more. The only advantage
of parallel splitting is the width of strips is in the range of 23 to 25 mm, which is suitable
for horizontal laminates. If proper design of blades are carried out which can fit into
radial splitting machine it is possible to obtain 25-30mm width size strips. In case of
radial splitting the width of the slabs are less but it is fast and wastage is also less. This
may be used as a core material in the horizontal laminates and can also be used for
vertical laminates. Hand splitting depends on the efficiency of the persons and also
number of blades present in the hand split equipment.
After splitting the strips are manually dressed with machete so that it can fit into the
knot removal machine. This machine needs some modification to suit Indian bamboos.
It was observed that the break down of the machine is more often during processing
which will be a bottleneck during continuous production. Hence it has to be reviewed
thoroughly before recommending for commercial production. The strips then either

can be sent to four side planning or it can be boiled with preservative to remove starch.
If the strips are boiled and then dried four side planning will be quick and the dust
comes out will be easily extracted from the dust extraction chamber. Since the diameter
of bamboo is less than 80 mm, the concavity is more in the strips thereby by planing
wastage is more, hence the strips obtained will be of 4 mm thickness only. If the
diameter of bamboo is in the range of 85 to 100 mm then the thickness of the strips can
be increased to 6 to 7 mm depending on the wall thickness of bamboo.
Properties of bamboo strips obtained from parallel splitting is higher than that of radial
splitting including density. This might be due to higher width of the splits in parallel
splitting. Properties of both species of bamboo in parallel splitting has given almost
13


same reasons. Vertical bamboo laminates made out of parallel split strips of the two
species of bamboo and it can be seen that there is not much difference between the
properties of Bambusa nutan and Dendrocalamus hemaltonii except that the strength is
directly proportional to the density of the final bamboo wood. Compressive strength,
block shear strength, screw holding strength [edgewise] is very much higher in case of
Dendrocalamus hemaltonii compare to Bambusa nutan. One of the reasons for this
might be the brittleness of Bumbusa nutan. The results summarized are based on
limited number of samples tested due to time constraints. It can be seen that the overall
yield varied from 9.5 to 11 percent. The yield can be improved, if the diameter of the
bamboo is more than 85 to 95 mm and also if some improvements are made in the
machinery used at various stages. The cost of the bamboo processed at the Institute
facilities available have been calculated, taking into consideration the cost of bamboo,
power consumed by each machine, labour, preservative chemicals, resin adhesives, etc.
This is only an indicative and there may be some difference in regular production. The
cost will also come down on regular production. In four side plaining machine the dust
extractor has to be improved to increase the efficiency. The process of making bamboo
laminates is more labour intensive and to increase the efficiency of the workers, proper

training has to be given not only in the operation of the machine but also in handling of
materials especially in the field of assembling, pressing and finishing, so that the
product quality and finishing can be improved considerably.
Observations and Suggestions
The present study aimed at finding out various process parameters of the manufacture
of bamboo laminates, performance of the available machinery, constrains involved and
suggest probable remedial measures.
Raw Material
The quality of bamboo required for manufacture of laminates can be discussed with
reference to hardness, girth, wall thickness, straightness, age, moisture content etc.
Hardness: Softer species cut better than the harder ones. High silica content accelerates
blunting of the cutting knifes/blades. During the study it was found that knot removal
and width sizing is found to be difficult with hard bamboo due to frequent jamming of
the machines and also fibre raising is higher.
Girth: One of the important factor controlling the yield and quality of strips is the girth
of the bamboo. Higher the girth of bamboo, easier to make strips and higher is the yield.
Girth of 100mm or more is suitable for conversion to strips. Bamboo having lower girth
is difficult to process using the available machines and the yield is also low due to
higher wastage. Bamboo with lower girth gives strips of concave nature the thickness of
the strips will come down considerably for converting into a rectangular strip.
Wall Thickness: It is one more important property of bamboo, which affect both
processing as well as yield of strips. Bamboo having wall thickness 10-15 mm have been
found ideal for processing to obtain increased yield. Strips having wall thickness less
than 6 mm is difficult to process because the cutter system cannot remove both the
14


epidermal and endodermal layers of the strips. With higher wall thickness of the
bamboo, the present knot removing machine are not suitable hence part of the thickness
have to be removed prior to processing in the knot removing machine. Thus the yield

becomes lower.
Straightness: This property of bamboo has profound importance on the yield and
quality of strips. During radial splitting of bamboo the splitting takes place along the
grain direction of the bamboo. If the bamboo is curved in nature, all the strips will be
curved. Such strips are difficult to process further. Same thing will also happen if the
splitting is done by hand. In the case of parallel splitting, the yield will come down as
wastage will be more during cutting of straight strips from a curved bamboo.
Age of Bamboo: Bamboo of age group 3-4 year old have been found most suitable for
making strips. Although bamboo matures in 1-1.5 years, the strength of the bamboo will
be very much less compared to higher age. More than 4 years old bamboo starts drying
and deteriorating and hence difficult to process and quality and yield of strips are also
poor.
Moisture Content: This is one very important factor affecting the quality of strips. The
ideal MC of bamboo for strip making is 50-60 per cent.
Selection of quality of bamboo is one of the important criteria to initiate manufacture
bamboo laminates. Selection has to be done at the source before felling. Procurement of
unwanted material will affect the yield and ultimately the economy of the production.
Table-10: Test data on Bamboo strips
Moisture content 10 –– 12 %
SL.NO

1

2

3

4

Properties

Density, g/m3
a. Average
b. Standard deviation
c.Variation Coefficient, %
Modulus of rupture,N/mm2
a. Average
b. Standard deviation
c.Variation Coefficient, %
Modulus of elasticity,N/mm2
a. Average
b. Standard deviation
c.Variation Coefficient, %
Compression strength,N/mm2
a. Average
b. Standard deviation
c.Variation Coefficient, %

Sample no Sample no Sample no
BN/R
BN/P
DH/P
0.61

0.81

0.86

146.9
42.5
29.2

218
63
29

225
48
21

25000
8100
32.5

35700
19400
54.2

37400
6500
17.3

47.12
14.32
30.4

45.6
21.2
46.5

50.4

17.9
35.6

Laminates withstood cyclic boil dry test without any delamination.
15


BN - Bambusa nutans
DH - Dendrocalmus Hemiltonii
P - Parallel
R - Radial
Table –– 11 Test data on Bamboo Laminates *(Vertical)
Moisture content 10 –– 12 %
SL.NO

Bambusa nutans

Dendrocalmus hemiltonii

B1

B2

B1

B2

0.81
0.02
1.69

0.78
0.02
1.94

0.77
0.01
0.67

0.99
0.01
1.47

103
-

68
-

93.9
-

236
-

12910
-

9870
-

12100
-

23400
-

93.27
6.78
7.27

81.71
0.59
0.72

76.89
9.06
11.78

124.2
5.59
4.50

-

-

-

-

2926
-

4055
-

3248
-

4285
-

1886
-

2088
-

1556
-

4000
-

Properties
g/cm3

1

2

3

4

5

6

Density,
a. Average
b. Standard deviation
c.Variation Coefficient, %
Modulus of rupture,N/mm2
a. Average
b. Standard deviation
c.Variation Coefficient, %
Modulus of elasticity,N/mm2
a. Average
b. Standard deviation
c.Variation Coefficient, %
Compression strength,N/mm2
a. Average
b. Standard deviation
c.Variation Coefficient, %
Block shear strength,N/mm2
a. Average
b. Standard deviation
c.Variation Coefficient, %

Screw withdrawal strength, N
i Face
a. Average
b. Standard deviation
c.Variation Coefficient, %
ii Edge
a. Average
b. Standard deviation
c.Variation Coefficient, %
.

* Made out of strips obtained by parallel splitting.

16


Table-12

Test data on Bamboo Laminates *(Horizontal)
Moisture content 10 –– 12 %
SL.NO

1

2

3

4

5

6

Properties
Density, g/cm3
a. Average
b. Standard deviation
c.Variation Coefficient, %
Modulus of rupture,N/mm2
a. Average
b. Standard deviation
c.Variation Coefficient, %
Modulus of elasticity,N/mm2
a. Average
b. Standard deviation
c.Variation Coefficient, %
Compression strength,N/mm2
a. Average
b. Standard deviation
c.Variation Coefficient, %
Block shear strength,N/mm2
a. Average
b. Standard deviation
c.Variation Coefficient, %
Screw withdrawal strength, N
i Face
a. Average
b. Standard deviation
c.Variation Coefficient, %

ii Edge
a. Average
b. Standard deviation
c.Variation Coefficient, %
.

Bambusa nutans

Dendrocalmus
Hemiltonii

0.81
0.02
2.73

0.92
0.01
1.59

152.6
-

151.4
-

12840
-

13740
-

81.37
0.59
0.72

119.59
3.06
2.55

8.63
1.18
13.65

14.05
0.09
0.65

2078
-

2260
-

3945
-

5588
-

* Made out of strips obtained by parallel splitting.

17


Table 13:% Yield of the Final Finished product ( Bamboo Laminates)
Intial
Wt.

Cross
cutting
wt

%
yield

Splitting

53.5
56.7
53.5
62.8
57.8
45
51.8

51.76
55.24
48.8
58.1
52.9

44.4
46.6

96.748
97.425
91.215
92.516
91.522
98.667
89.961

51.7
32
48.2
36.8
52.4
24.3
26.3

42.8

41.8

97.664

18

Drying

%

yield

Four
side
plaining

%
yield

Sorting &
pressing

%
yield

72.5

25.8

48

10.3

19.3

7.3

14

23.4

38
25.1
28.7
20
16.9

41.3
71
40
49.7
44.4
32.6

17.7
29.6
18.4
22.3
15.1
11.7

31
55
29
39
34
23

8.8
12.8
8.3

9.5
6.3
8.1

15.5
23.9
13.2
16.4
14
15.6

6.7
7.8
7.7
7
0
6.3

12
15
12
12
0
12

15

35

11.8

28

5.1

11.9

4.4

10

%
yield

Knot
removal

%
yield

96.6

38.8

56.4
90.1
58.6
90.7
54
50.8

Rejecte
d
42.1

Trimming
& plaining

%
Yield

5.2
5.8
6.4
6
6

9.72
10.23
11.96
9.55
10.38

18


TABLE 14: POWER CONSUMPTION
Process

Cross cutting

Parallel
splitting
Radial
splitting
Internal &
External
Knot
removal
Sliver
Drying &
Chemical
Impregnation
Four side
planning

Unit

No of
cross
cuts

9250

Culms
of
1.2m/hr
Culms
of
1.2m/hr
Strips

of
1.2m/hr

450

Plaining
Total:

Actual
output
per hr

Machine

HP of
m/c

Hrs
Required

Power

Total Units

Kw-hr

In 300 days

19.27

2

28.7508

8625.25

15

30

3

67.14

20142

1400

100

14

7.5

78.33

23499

44050

1000

44.05

15

492.92

147875.85

42.33

1515.75

454725.792

547.688

164306.5

480

strips

44050

Strips
of
1.2m/hr
m2

44050

900
6.954

32

10

238.72

71616

Parquet
pieces

204.28
(in 2
shifts)
1824
(both
sides of
parquet)

90

20.26

2

30.2279

9068.376

m2

204.28

16

2

23.872

71616

Pressing
Trimming

Unit to
be
processed
per day

48

48.94444 15

98.83

971474.768

At 80% load factor, and Rs.3.5/ unit,
Cost of power is 971474 x .8 x 3.5 = Rs.27.2 lakhs

19


Table 15: CAPAC ITY UTILIZATION OF VARIOUS MACHINES

Process

Unit

Unit to
be
processed
per day

Actual
output
per hr

Machine

Machine
Utilisation

No. of

Machines
Required

Hrs
Required

Cross cutting

No of
cross
cuts

9250

480

19.27

2.4

3

Parallel
splitting

Culms
of
1.2m/hr
Culms
of

1.2m/hr
Strips
of
1.2m/hr

450

15

30

3.75

1400

100

14

1.75

2(
double
station)
2

44050

1000

44.05

5.50625

5

Radial
splitting
Internal &
External
Knot
removal
Sliver
Drying &
Chemical
Impregnation
Four side
planning

strips

44050

Strips
of
1.2m/hr
m2

44050

900

48.94444

6.118056

6

6.954

32

4

2

Parquet
pieces

204.28
(in 2
shifts)
1824
(both
sides of
parquet)

90

20.26

2.5

2

m2

204.28

Pressing
Trimming

48

16

2

2

Plaining
Total:

20


Technology Profile for a Bamboo Board Manufacturing Unit
Assumptions
1. Assuming that all machines operate at 70% of production capacity
2. For obtaining a true picture, actual data from trial runs of indigenously developed machinery has

been assumed
3. From observations that that the radial splitting is more than 6 times faster than parallel splitting,
wastage is almost nil but wastage during subsequent stages are more than in parallel spitting, it
has been assumed that 70% of cross cuts are split radially. Slightly larger diameter straight cross
cuts undergo parallel splitting
4. Cost of bamboo culm has been assumed at Rs.25/pole from where 4 sections can be obtained and
6 strips from each cross cut
5. Assuming spacers take up some portion of the platen, the number of parquet in each operation is
taken as 19. The press has been assumed to run for two shifts to maintain production capacity.
6. Energy per unit has been assumed at Rs.3.5 and 80% load utilization
7. Covered area of 90sq m for the factory @4500/ sq m has been assumed
8. Contribution of the promoter is 30% of the total project cost. The margin working capital of 30%
the total working capital is included within project cost
9. The final product will be unfinished boards which for use as flooring tile would require sanding
and surface coating

21


Project Cost
Unit cost
Cost
Total
Rs in lakhs Rs in lakhs Rs in lakhs

Partticulars
I. Land and
Land Development
Land and land development , 2 Acres
of Land @ Rs. 1.5Lakh/Acre

Sub-Total I

12.00

II. Civil Work
1) Fencing with barbed wire
and live Fencing m.
2) Gates with RCC pillars
3) Building sq.mt
4) Boring,Water storage ,
distribution/drainage and
general illumination, piping.
5) Electrification.
Sub-Total II
III Plant and Machinery

Processing Machinery
1) Cross-cutting
2) Parallel Splitting
3)Radial Splitting
4) Knot removal and width sizing
5)Four side plaining
6) Surface Planer
Sub-Total III
Other Equipment
1) Drying & Chemical Impregnation
2) Hot press 8ft x 4ft
3) Grinding
4) Trolleys

5) Measuring instruments including lab
6)Standby Generator 325 KVA
7) Air compressor
8) D.D.Saw
9) Boiler
10) Oil heated resin kettle
11) Glue mixer
12) Maintenance costs with tools

4.7
2
1
90sq m 4500/sq m

0.00001
40
4.00

4.00
52.70

3
2
2
5
6
2

0.35
0.70

2.14
4.74
3.50
1.25

1.05
1.4
4.28
23.7
21
2.5
53.93

1
2
1
6

22.66
10.00
0.50
0.10

1
1
1
1
1
1
1

12.00
0.25
1.25
7.00
2.00
0.50
0.60

22.66
20
0.5
0.6
1
12
0.25
1.25
7
2
0.5
0.6

Sub-Total IV
V Electrical Power and
Water Supply.

68.36

1) Electrical installation for
about 350KVA load.

2) Water supply including

12
2

22


storage tank of 5000 liter
capacity
Sub-Total V

Miscellaneous

1) Vehicle (Mini Truck)
2) Jeep/car
3) Communication
4) Office equipements
5) Furniture and fixture
Sub-Total VI

14.00

1
1

7.00
5.00
2
4.00

2.50
20.50
221.49

Total Capital cost (I toVI)
VI Prelimnary and
preoperative expences.

(5% of Project Cost)

VII Margin money for
working capital.

(30% of working capital)

11.075

72

VIII Contigencies

0.50

A )Total Project Cost.

305.06

23

PRODUCTION COST OF UNFINISHED BAMBOO LAMINATES
(On the basis of 300days in 8 hours working)
I

II

Rs. in Lakhs

Total in Lakhs

Raw Material
Bamboo
Adhesive
Preservative
Releasing agent Bopp film

138.75
13.17
3.95
16.04

171.91

Energy and other Manufacturing costs
Maintenance charges

30.00
6.00

36.00

III Salaries, wages and Overheads
Salaries
Managerial staff
Factory manager
Foremen
Supervisory staff
Sales manager
Administration
Casual labours and security to
Staff

2.40
1.80
0.72
1.92
0.96
1.92
21.0

30.72

IV Sales promotion and commission to
dealers

2

V

240.63

Total Production cost for 61286.4 sq mts
(300days)
Production cost Per sq mt in Rs.
Add Depreciation
Buildings
Machinery

254.69
.50
8.00

8.50

Add Interest
Term loan of Rs213 lakhs @3.5%
7.47
Working Capital loan Rs.72 lakhs @3.5% 2.52

9.99

Total Manufacturing Costs
Production cost per sq mt in Rs
Production cost per square feet in Rs

259.12
422.8
~ Rs.39

24

Raw Material Assessment

Sl

Particulars

Dimensions

Value

1.12m
x .001344
10cm
x
12mm
b
Volume of one strip after four side 1.12mx20mm 89600
planing
x 4mm
c
Surface area of each parquet
1.12m
x 0.112
0.10m
d
Surface of hydraulic machine platen
1.22
x

2.14
f
No. of parquet which can be made in one
19
operation (d/c)
g
No. of cycles per hour
3
h
Area of parquet which can be made in
102.14
two 8 hr shifts(16 x g x f x c)
i
Annual Production in 2 shifts using 2
61286.4
presses
j
No of parquets per annum(i/c)
547200
k
Strips required per parquet
21
l
Total no. of strips required per annum(j/k)
11491200
Assuming about 15% of wastage due to colour and dimension variations
n
No. of strips required for maintaining
13214880
production capacity per annum

o
No. of strips required for maintaining
44050
production capacity per shift(m/300)
l
No of bamboo culms of approx. dia Assuming 4 1850
cuts
(85cm ) and length (5m ) required per cross
and 6 strips (1836)
shift (o/4 x 6)
from
each
cross cut
a

Volume of each parquet

Unit
m3
mm3
m2
m2
Pieces
m2
m2
pieces
pieces
pieces
pieces
pieces

Pieces

25