Final composites file9

DEPARTMENT OF MECHANICAL AND INDUSTRIAL ENGINEERING
Report for the course project, Dec 2011; MECH-6521
Page 1
PRINCIPLES OF THE MANUFACTURING OF
COMPOSITE MATERAILS
MECH 6521 FALL -2011
MANUFACTURING
OF
COMPOSITE CHAIR
SUBMITTED TO: DR. SUONG V. HOA
PROJECT COORDINATOR: DR.MING XIE
SUBMITTED BY: Asmita Dubey 9796924
Charanpreet Singh Heer 6420753
Israt Jahan Eshita 9806946
Rajan Gupta 5769035
Rohit Katarya 6306160
Vikas Pandit 6238394
Number of pages: 18
Number of words: 2325

Page 2
Contents
Objective..........................................................................................................................................
1.Introduction................................................................................................................................ 3
2.Experimental procedure in lying up and making the seat ..................................................... 4
2.1.Selecting of material............................................................................................................ 4
2.2.Cleaning the mould surface ................................................................................................ 5
2.3.Applying releasing agent..................................................................................................... 5
2.4.Placement of pre-pregs........................................................................................................ 6
2.5.Curing................................................................................................................................... 7
3.Process Parameters, time, temperature, pressure................................................................... 8
3.1.Quality of Part as measured by............................................................................................
3.2.Optical microscope observation ......................................................................................... 9
3.3.Mechanical property from sitting test ..................................Error! Bookmark not defined.
4.Cost Estimation .........................................................................................................................15
5.Results ............................................................................................Error! Bookmark not defined.
6.Conclusions....................................................................................Error! Bookmark not defined.
7.Appendix................................................................................................................................... 18
References.................................................................................................................................... 20

Page 3
1. Introduction
Composite materials for construction, engineering, and other similar applications are formed by
combining two or more materials in such a way that the constituents of the composite materials are
still distinguishable and not fully blended. The two main constituents of composite materials
include fiber and matrix. However, one can use fillers to add extra strength to the product. Each
constituent of composite material has its own unique role to play.
A) Matrix in composite materials gives the shape to the composite part, protects the
reinforcements to the environment, transfer loads to reinforcements.
B) The aim of reinforcements i.e. fibres, in composites are to get strength, stiffness and other
mechanical properties, dominate other properties as coefficient of thermal extension,
conductivity and thermal transport.
C) Fillers like glass wool and other Nano particles give such properties to the material that
makes it unique from the other metallic or non-metallic materials.
Therefore, Composite materials have excellent compressibility combined with good tensile strength
[1]. Depending upon the type of geometry of product and type of resin used, there could be many
different techniques of to manufacture the composite materials. Like hand layup, fiber or filament
winding i.e. bradding, liquid composite molding (L.C.M), Pulltrusion, fiber placement etc. are some
few techniques of manufacturing. The type of resin used tells us whether the process is going to be
inside or out of autoclave. During the manufacturing, various defects like voids (porosity), Fibre
wrinkling, Fibre misalignment, distortion, inadequate wetting out of fibres. [4] etc. could be faced.
All of these defects reduce the performance and life of the product.
In the present project, as the geometry of product to be formed was not so complex. So, hand layup
technique was employed. The resin used was polyester that makes the process out of auto clave.
The glass fibers were used as a reinforcement material.

Page 4
2. Experimental procedure in lying up and making the seat
2.1 Selection of material
Selection of materials and specimen is very important for the manufacturing of a good quality
composite chair. In this project, glass fibre having plain weave fabrics and polyester along with
Plastic mould of chair was used.“A plain weave fabric is made by interlacing yearns in an
alternating over-and-under pattern. There is one warp fibre for one fill fibre without skipping. The
pattern gives uniform strength in two directions.” The skins are made from glass fibres and
polyester resins. Since the fabrics give uniform strength in two directions, we placed the layers over
each other without changing the angle.
As per our requirement of making the chair that can bear the load of 80Kgs, we choose
A) Glass- fibres,for reinforcement as it is cheaper and strong enough to bear that much load.
Fig. 1 Glass fibre fabric
B) Polyester resin, provide better packing of the material and this in turn gives higher
density, better strength, stiffness and environmental resistance and overall it does not need
autoclave for its curing.
Fig. 2 polyester as a resin

Page 5
C) Cobalt, accelerates the curing process, but it also reduces the pot life of the resin so we
used it in a very small amount,
Fig. 3 cobalt
2.2 Cleaning the mould surface
The mould surface should be cleaned properly as the final surface finish depends on it. Otherwise,
the surface finish would not be good. For to clean the mold surface, Frekote 700 N/c solution was
used. Extra material from the mould surface was scratched till it became smooth and clean.
Fig. 4 cleaning of mould Fig. 5 Application of Frekote 700 N/c

Page 6
2.3Applying releasing agent
To remove the final product easily from the mould, release agent (Air Tech 2) was applied on the
mould surface. Later a sheet of fine fibre was then used to cover the mould for easy removal of the
final seat from the mould surface.
Fig. 6 Application of releasing agent Fig. 7 Application of fine fiber sheet
2.4 Placement of glass fibre fabric and Resin
Glass fibre sheet was cut according to the dimensions of mould. After the cutting was done, it was
placed and rolled properly on the same mould. Then for each layer of glass fibres, the resin was
prepared by stirring 400g of polyester and styrene with 0.8 g of cobalt well for 1 minute. After the
mixing of cobalt, 8g of MEKP was added and again the whole solution was stirred for another 5
minutes. This process was repeated for four glass fabric layers

Page 7
Fig. 8 Placement of fiber sheet Fig. 9 Application of resin
2.5Application of vacuum
In order to avoid the air entrapments, dry spots and resin rich areas, vacuum was applied. To do
the vacuuming, the samples were wrapped using Teflon and then breather material over it. Then
vacuum was generated using the suction pump.
Fig. 10 Breather placement Fig. 11 Vacuum application

Page 8
2.6Curing
The curing of polyester resin takes place at room temperature. So, autoclave was not used
throughout the process. And this was observed that only 4-5 hours were required for the complete
curing of product.
2.7Attachment of legs with the base
The final and most challenging task was to attach the legs with the base of seat so formed. As
bonding is the best way to attach something with the composite. So, In order to accomplish the task,
the plastic plate was bonded with the base using the smaller layers of same fabric. After the
solidification, the legs were simply screwed with the plate.
Fig. 12 Attachment of plate with base

Page 9
3 Optical microscope observation
3.1 Microstructure examination:
The mechanical property of any component made out from any composite material depends upon
its microstructure. In order to know about the microstructure of the chair, the microstructure
examination was done. This experimentation requires various steps to be followed, so that each and
every fibre should become visible under the microscope. Also the defects like voids, resin rich and
poor areas could be examined and appropriate value for volume fraction of fibre can be calculated.
The steps followed during the examination may consist of sample preparation, grinding, polishing
and analysing the specimens.
1. Sample preparation:
A) Firstly, 3 samples of 22.88 mm * 23.96 mm each with the help of diamond cutter were
taken out form the unwanted portion of the seat refer fig... The first and third samples were
taken out from the straight portion and the second sample was taken out from the curved
portion of the seat as shown in fig. 13.
Fig. 13 shows the samples positions

Page 10
Fig. 14 Preparation of sample Fig. 15 Molds containing solution & samples
B) Secondly, in order to mount the samples in the plastic containers, the solution using Epon
Resin 828 and Curing Agent 3046 was prepared. For each 100g Epon resin 828, 45g Cure
Agent 3046 should be added. After mixing the solution, the vacuum was applied for 15-20
minutes, so that no air bubbles should be remained in the solution and then the same
solution was poured into two moulds, shown in fig. 15. After 24 hrs the solution got
solidified and was taken out from moulds. Figure number 16, shows the samples after
complete solidification.
Fig. 16 Final samples

Page 11
2. Grinding and polishing
Fig. 17 Grinding Machine
After preparing the samples, the grinding operation is to be done. The grinding machine upon
which different grades of grinding papers were easy to mount and was capable of running at
variable speeds was used. Figure 17, shows the grinding machine used to grind the samples. The
grinding was done using silicon carbide paper of grade 240, 320, 400, 600, 800, 1200
sequentially. Diamond extender was used as the polishing solution and diamond suspensions (3µm
and 1µm) were used for primary polishing and colloidal silica suspension (0.05 µm) was then used
for final polishing, refer figure 18. Nylon artic and imperial was used for primary and final
polishing. The table no. 1 was referred throughout the process.

Page 12
Fig. 18 Grinding of samples
Table 1. Grinding and polishing (for Epon 828 with Epicure 3046)
Step Type Surface Grit size Lubrication Pressure
(psi)
Load per
Specimen
(lbf)
Rotation
Speed
(rpm)
Time
0 Grinding SiC Disc 240 Water 15 3 250 30 Sec
1 Grinding SiC Disc 320 Water 10-15 3 250 30 Sec
Repeat Step 1 unil ﬂatness of all samples
2 Grinding SiC Disc 600 Water 7‐10 3 250 30 Sec
3 Fine
Grinding
SiC Disc 800 Water 10‐15 3 250 45 Sec
4 Fine
Grinding
SiC Disc 800 Water 10‐15 3 250 45 Sec
5 Polishing Nylon
Artic
3 Micron
Diamond
Suspension
Water based
diamond
extender
17‐25 5 150 4 min
6 Polishing Nylon
Artic
1 Micron
Diamond
Suspension
Water based
diamond
extender
17‐25 5 150 4 min
7 Fine
polishing
Imperial 0.05 micron
SiC
Suspension
Norle 20‐30 6 150 5 min

Page 13
3. Analysis of specimen
After the preparation of samples, the unpolished side of the specimen was cut to make it straight so
that one can analyse those same samples correctly. Now, the specimens were placed under the
microscope, the magnification power of the lenses used was increased step by step. At 10X the
images were taken out using image analyser software. Fig. 19, shows the microscope used and
figure no. 20, 21, 22. shows the images of the samples taken.
Fig. 19 Microscope

Page 14
Microscopic images of samples
Fig. 20 Fig. 21
Fig. 22

Page 15
Though, the cross-section of fibres appeared to be somehow elliptical, but the calculations for
diameter of fibres were done by taking it to be circular in cross-section. Some voids, resin rich
area and dry spots were identified, which eventually lead to lower the strength of the sample.
Figure number 20, clearly shows the orientations of fibers in 0 and 90 degrees. The vertical
lines show fibers at 0 degrees and the circles shows the fibers at 90 degrees. The dark black
portions show the defects in the samples.
3.2 Calculations for fibre volume fraction:
51.9 μm 57.9 μm
Sample 1 sample 3
53 μm
Sample 2
Fig. 23 shows the sections of samples 1, 2, 3 under microscope

Page 16
In order to calculate the volume fraction of the fibre, the square elements of lengths 51.9, 57.9
& 53 micro meters from the microscope snap shots for sample 1, 3 and 2 are taken into
consideration.
For sample 1 square element, the number of fibres in this square element observed as 9 fibres
and the diameter of each fibre is calculated to 16 micrometers. Therefore the total area
occupied by 9 fibres and area of square element can be calculated and by using the relation for
volume fraction, given by:
The value for Volume fraction for fibres can be calculated and comes out to be 66.965%.
For sample 3, diameter of fibre is comes out to be 16.2 micrometers and by using the above
relationship; the volume fraction is calculated to 61.5%.
Also, same calculations for sample 2 are performed with diameter of fibre and length of square
element taken as 15.47 micrometer, 53 micrometer respectively, the volume fraction of fibres
come out to be equal to 60.25%.
4. Cost Analysis:
In order to have a good idea about the expenses of whole project, the costs related to almost all
the materials and labour costs per hour were taken into consideration. Table no 2 & 3 show the
total cost for materials and Labour costs respectively.

Page 17
A) Material cost details:
Table no. 2 Total Material Cost
Material used Quantity Unit Cost (CAD$) Total Cost
(CAD $)
Woven glass fiber
sheet
3.65$ per lb 11
Polyester with
styrene
MEKP
Cobalt
Breather 5.9 $ per Yard 2.5
Release Film 0.25 $ per Kg 0.1
Release Agent 14 $ per 100ml 2.8
Legs 10
Sum

Page 18
B) Labor Cost Detail:
Table no. 3 Total labor cost
Type of work Persons involved Unit Cost
(CAD$ /hrs.)
Time taken
(Hrs.)
Cost (CAD $)
Preparing materials and
cutting
2 10 3 60
Laying up 3 14 3 126
Grinding 2 14 1 28
Inspection(Macroscopic
and Microscopic)
1 14 1/2 7
Other cost 20
Sum 241

Page 19
Appedix
Table no. 4 Materials and equipment used in the whole project
S.no. Material and
equipment
Specification and application Dimension
( if any )
Quantity
1. Mold Plastic chair to give the shape to your chair Fig
. 4
1
2. Woven fabric
sheet
Glass fiber 4
3. Cleaning agent Frekote 700 N/c 200 gm
4. Breather Non woven ultra high temperature breather,
Air wave UHT-800 For proper vacuuming at
elevated temperature.
5. Release film Release film 5200 MFG-Airtech, For easy
removal from the mould
6. Adhesive tape Yellow, 2 cm wide ,for proper sealing the
vacuum bag
1 roll
7. Vacuum plastic
bag
Plastic sheet, to create vacuum
8. Vacuum pump Max pressure inlet -150PSIG, Max
temperature-125◦F ,product no -3532-1082,To
suck the air from the composite
1
9. Cutting Machine Small diamond cutter , too cut the samples 1
10. Polyester resin (
for Mounting)
To make composite and adhesion to the layers
and plastic plate
11. oven Fisher, small isotemperature vacuum oven
model no-281
1
12. Polishing
Machine
To smooth the sample for further test 1
13. Optical digital
microscope
To analyse the quality of the composite we
prepared for your seat.
1
14 MEKKP For curing process

Page 20
References

Final composites file9

More Related Content

What's hot (20)

Similar to Final composites file9 (20)

Recently uploaded (20)

Final composites file9