DESCRIPTION
Field of invention: Composite Materials
Background of Invention:
Metal Matrix Composite (MMC) can be produced by various techmques whch include liquid
state fabrication methods and solid state fabrication methods, out of whch stir casting is the
most economical' and widely used method around the world for production of MMC. Stir
casting is a liquid state method of composite materials fabrication, in which a dispersed phase
(ceramic particles) is mixed with a molten matrix metal by means of mechanical stirring. It is
the simplest and the most cost effective method of liquid state fabrication. The liquid composite
material is then cast by conventional casting methods and may also be processed by
conventional metal forming technologes. In this process particles are often tend to form
agglomerates, whch can be only dissolved by intense stimng. However, gas access into the
melt must be absolutely avoided, since ths could lead to unwanted porosities or reactions.
Careful attention must be paid to the dispersion of the reinforcement components, so that the
reactivity of the components used is coordinated with the temperature of the melt and the
duration of stirring, since reactions with the melt can lead to the dissolution of the
reinforcement components. Because of the lower surface to.volume ratio of spherical particles,
reactivity is usually less critical with stirred particle reinforcement than with fibers.
Detailed Description of the Invention:
For the production of MMC, stir casting setup incluQng the stirrer assembly was developed.
The main problem that persists with the stir cast techque for the production of MMC is the
agglomeration, porosity and the non -uniform distribution of the reinforcement particles that
are added to enhance the properties of the matrix material. Keeping this in mind a novel setup
is developed which will counter these problems and helps create low cost and high quality
MMC free from these defects. The stir casting setup includes various components whlch
includes muffle furnace, stirrer stand, stirrer slider, heat shield, c-plate, stirrer rod, and stirrer
impeller. The muffle furnace is having inlet and outlet gas ports through whch an inert gas can
be fed into the furnace to shield the melt from getting in contact with the atmospheric gases
thus eliminating porosity (figure 1.1). A stirrer assembly is designed and developed to create
vortex in the melt which will eradicate the conventional problems like agglomeration and nonuniform
distribution of the reinforcement particles related with the development of MMC.
Detailed design of the various components along with a 3D model of the setup is shown below'
(figure 1.1 - 1.9).
The design of the stirrer base stand is shown in figure 1.2. The height of the base stand is 62"
fiom the floor whlch gives us the freedom to use the stirrer with Qfferent sizes of the furnace.
The base of the stirrer is provided with ribs for malung the structure more rigid.
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function of the C-plate is to hold the DC
x P a cut into the plate for placing the digtal
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, .
1 RPM meter whch shows the value of revolution the stirrer is making per minute and another
slot to put the systems onloff switch.
The design of the stirrer slider is shown in figure 1.4. The function of the s1ider.i~to enable the
stirrer assembly to slide in the vertical duection along the length of the stirrer base stand. The
stirrer slider is equipped with a bolt assembly whch can stop the stirrer assembly to any desired
position wihn the boundary of the developed system. The stirrer slider is also equipped with
the arrangement of placing the rpm sensor which senses the rotation of the impeller blade by a
nut bolt assembly whch is attached on the sleeve of the rotating motor thus enabling us to read
the rpm of the DC motor.
The design of the heat sheld is shown in figure 1.5. The function of the heat shield is to protect
the motor from the heat of the furnace whch can damage the motor coils. The bottom face of
the heat sheld is provided with a ceramic blanket whch restricts the transfer of heat from the
furnace to DC motor thus protecting the system from getting damaged from overheating.
The design of the stirrer blades are shown in figure 1.6. The function of the stirrer blades is to
I create vortex in the melt whch enables the reinforcement to be uniformly distributed in the
melt and avoids the agglomeration of the particles during the casting process. The figure shows
three different impeller blades having blade angle of 90°, 120" and 180" which can be used to
vary the intensity of the vortex forces. The stirrer along with the impeller blades is made from
stainless steel (Grade 304) whch has very high melting point (1400°C) thus malang it suitable
to be used with casting of metals having low melting point.
! The design of the stirrer assembly is shown in figure 1.7 which shows the assembled view of
the sti,rrer assembly. Individual parts are marked and are shown in the table provided in the
I figure. The 3D model of the furnace along with the stirrer is shown in figure 1.8 and figure 1.9
respectively.
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. . Brief description of the drawings:
. .
. . . Figure 1.1 : ~esign'otfh e muMe furnace
. . 1:. Figure 1.2: Design of stirrer base stand
Figure 1.3: Design of C-plate for mounting the DC motor '
Figure 1.4: Design of the stirrer slider
Figure 1.5: ~esignof the heat shield
Figure 1.6: Design ofstirrers used for creating vortex in the melt
Figure 1.7: Stirrer mechanism design of the complete assembly
Figure 1.8: 3D model of the muffle furnace used for the production of MMC
Figure 1.9: 3D model of the stirrer assembly

CLAIMS
We claim:
1. The muffle furnace is designed with inlet and outlet gas ports through whch any inert
gas can be fed into the furnace which will help eliminate gas entrapment in the
developed MMC.
2. The developed furnace is designed to acheve temperature of 1000" C.
3. The furnace mouth is designed with a size of 8"x8"x14" whch can ackmrnodate -
various sizes of the crucible.
4. The stirrer base stand IS having height of 62" whch provides us the freedom of using
the stirrer with various sizes of the furnace.
5. The stirrer can be locked at different heights (ranging from 0-30" from the top of the
base stand) depending upon the height of the furnace used for production of casting.
6. The developed system is portable and cost effective whch can be used to produce
casting of very hlgh quality and low cost.
7. The stirrer assembly is designed and developed whch can acheve rotation from zero to
1500 rpm (rated capacity of the installed motor) without any wobbling effect of the
stirrer rod.
8. The stirrer rods are designed with dfferent blade angles so as to produce vortex in the
melt which will help eliminate agglomeration effect and will aid in the uniform
distribution of the reinforcement particles.
9. The developed product is designed, developed, and tested successfully. The setup was
used to produce more than 50 (fifty) aluminium castings successfully with 5 minutes of
stirring time for each casting.