16-09-2016, 04:21 PM
1454998555-ProductionTechnology.pdf (Size: 5.4 MB / Downloads: 117)
Aim:
The automobile components such as piston, connecting rod, crankshaft, engine block,
front axle, frame, body etc., are manufactured by various types of production processes
involving casting, welding, machining, metal forming, power metallurgy etc. Hence B.E.
Automobile Engineering students must study this course Production Technology
Objectives:
To study and understand manufacturing of various types of production processes
involving casting, welding, machining, metal forming, power metallurgy etc
To study and understand manufacturing of automobile components such as piston,
connecting rod, crankshaft, engine block, front axle, frame, body etc
TEXT BOOKS
1.
2.
Hajra Choudhury, “Elements of Workshop Technology”, Vol. I and II, Media
Promoters and Publishers Pvt., Ltd., Mumbai, 2005.
Nagendra Parashar B.S. and Mittal R.K., “Elements of Manufacturing Processes”,
Prentice-Hall of India Private Limited, 2007.
CASTING:
Casting is a manufacturing process by which a liquid material is usually poured into a
mold, which contains a hollow cavity of the desired shape, and then allowed to solidify.
The solidified part is also known as a casting, which is ejected or broken out of the mold
to complete the process. Casting materials are usually metals or various cold setting
materials that cure after mixing two or more components together; examples are epoxy,
concrete, plaster and clay. Casting is most often used for making complex shapes that
would be otherwise difficult or uneconomical to make by other methods
CASTING AND PHASE DIAGRAMS
OBJECTIVE
In this experiment, you will become familiar with sand casting, a common industrial
fabrication process. Upon completion of the module you should be able to use
equilibrium phase diagrams to interpret solidification processes.
Casting, one of the oldest manufacturing processes, consists of pouring a molten metal
into a mold cavity, where it solidifies in the shape of the cavity. Casting can produce
complex shapes (including internal cavities) and large parts with small material wastage.
A disadvantage of casting is that during solidification, coring occurs, and as a result,
solute elements are concentrated at the grain boundaries. If these elements form brittle
particles, the cast alloy will have a low ductility. A post-casting normalizing heat
treatment may reduce the solute segregation.
In this lab, you will make a sand mold and assist in the melting and casting processes.
You will get exposure to the process parameters in casting: fluid flow, heat transfer,
metal solidification rates, and design of the metal feeding system. Thermocouples
embedded in thick and thin sections of each mold will be used to generate direct cooling
curves. Inflection temperatures will be compared to the equilibrium liquidus and solidus
of the alloy system.
PROCEDURE FOR MAKING THE CASTING
1.
2.
Make a mold from the oil bonded sand. Place one thermocouple in the thin
section and one in the thick section of the mold.
Begin melting the metal in the induction furnace as mold nears completion. Be
sure to wear safety gear around the furnace. Set-up the PC data acquisition
system and the Notebook program.
3.
4.
5.
6.
Place the mold in the sandbox. Connect the thermocouples to the leads from the
PC data acquisition system.
Skim the oxide from the surface of the melt. Remove furnace from the crucible,
start the data collection program, and pour the metal into the sand mold.
CAUTION! Students not assisting in the pouring operation should stand back as
splattering of the molten metal may occur. Remember, the aluminum is above
600C. Also, the oil in the molding sand will begin to burn, giving off noxious
fumes.
After solidification and cooling (>10 min.) remove the casting from the mold and
inspect it.
METAL CASTING PROCESSES
Casting is the process of forming objects by pouring liquid or viscous
material into a prepared mold or form.
Examples: Carburetors, frying pans, engine blocks, crankshafts, railroad-car wheels,
plumbing fixture, power tools, gun barrels, machine tool is bases etc.
Properly designed and properly produced castings do not have directional properties.
Casting can produce complex shapes. Cast iron has also very good dampening
characteristics.
Importance of casting
Complex shapes can be produced.
Minimal directional properties are obtained
Hollow sections can be produced
Very large part can be produced.
Metals that are very difficult to machine can be used to produce an object.
Metals that can be casted
Iron, steel, Al, brass, bronze, Magnesium and certain Zinc alloys.
Various Casting processes have been developed; each has its own
characteristics and applications to meets specific engineering and service
requirements.
Sand casting,
Die Casting,
Centrifugal Casting,
Shell-Mold Casting,