Manufacturing Process - Introduction, Steps in Sand Casting, Patterns, Binders, Additives

1. Manufacturing Process
In industries, many different processes or
manufacturing methods are used. To be able to select
the technically and economically best manufacturing
sequence for a product, it is necessary to have a broad
fundamental knowledge of the possibilities and
limitations of the various manufacturing processes,
including work materials used and geometries, surface
finishes & tolerances required.
The term process can in general be defined as a change
in the properties of an object, including geometry,
hardness, state, information content (form data), and
so on.

2. The progress and the prosperity of human civilization
are governed and judged mainly by improvement and
maintenance of standard of living through availability
or production of ample and quality goods and
services for men’s material welfare (MMW) in all
respects covering housing, clothing, medicine,
education, transport, communication and also
entertainment. The successful creation of men’s
material welfare (MMW) depends mainly on
• availability of natural resources (NR)
• exertion of human effort (HE); both physical and
mental
• development and use of power tools and machines
(tools), etc.

3. Production or manufacturing can be simply
defined as value addition processes by which raw
materials of low utility and value due to its
inadequate material properties and poor or
irregular size, shape and finish are converted into
high utility and valued products with definite
dimensions, forms and finish imparting some
functional ability.
Manufacturing Process basically deals with the
conversion of raw materials to end product or
useful material (output or finished product or
component).

4. Manufacturing Processes refers to science and technology
of manufacturing products effectively, efficiently,
economically and environment-friendly through
• Application of any existing manufacturing processes and
system
• Proper selection of input materials, tools, machines and
environments.
• Improvement of the existing materials and processes
• Development of new materials, systems, processes and
techniques
All such manufacturing processes, systems, techniques have
to be
• Technologically acceptable , • Technically feasible
• Economically viable , • Eco-friendly

5. Classification of Manufacturing Processes
It is extremely difficult to tell the exact number of various
manufacturing processes existing and are being practiced
presently because a spectacularly large number of processes
have been developed till now and the number is still
increasing exponentially with the growing demands and rapid
progress in science and technology. However, manufacturing
processes can be broadly classified in four major groups as
follows:
(a) Shaping or forming : manufacturing a solid product of definite size
and shape from a given material taken in three possible states:
• solid state – e.g., forging, rolling, extrusion, drawing, etc.
•liquid or semi-liquid state – e.g., casting, injection molding , etc.
• powder form – e.g., powder metallurgical process.

6. (b) Joining process : Welding, brazing, soldering etc.
(c) Removal process : Machining
(Traditional – turning, drilling, milling, shaping, grinding or
Non-traditional – ECM, EDM, ECG, EBM,LBM, Ultrasonic
Machining, photochemical Machining, etc.)
(d) Regenerative manufacturing : Production of solid
products in layer by layer from raw materials in different
form: (Rapid Prototyping & Manufacturing)
• liquid – e.g., Stereo Lithography (STL)
• powder – e.g., Selective Laser Sintering (SLS)
• sheet – e.g., Laminated Object Manufacturing (LOM)
• wire – e.g., Fused Deposition Modeling FDM)

7. Fundamentals of Casting
Casting, one of the oldest manufacturing processes, dates
back to 4000 B.C. when copper arrowheads were made.
Casting processes basically involves the introduction of
molten metal into a mold cavity, where upon
solidification, the metal takes on the shape of the mold
cavity.
Simple and complicated shapes can be made from any
metal that can be melted.
Example of cast parts: frames, structural parts, machine
components, engine blocks, valves, pipes, statues,
ornamental artefacts, ……
Casting sizes range from few mm (teeth of a zipper) to 10 m
(propellers of ocean liners).

8. ● Introduction of molten metal into a mold cavity
where the metal confirms to the shape of the
cavity
● Intricate shapes in a single piece
● Internal cavities
● Very small and hollow parts can be produced
Important factors in casting operations
● Solidification
● Molten metal into mold cavity
● Heat transfer during solidification and cooling of
the metal in the mold
● Influence of the type of the mold material

9. Components are produced by pouring molten metal into a
contoured (mould) cavity followed by cooling to a solid
mass.
Cooled solid mass represents the configuration of the cavity
and is the required shape of the component.
Components thus produced are referred to as castings.
The cavity corresponding to the shape of the components is
called as the mould.
The mould may be made of refractory grains (sand moulds)
or metal (metal moulds).
The cooling of liquid metal to solid metal is termed phase
transformation.
The place where this activity is carried out is referred to as
foundry.

10. Steps in Sand Casting
- Pattern making
- Core making
- Gating systems
Furnaces Solidification Shakeout Additional heat Defects
Removal of risers treatment Pressure tightness
and gates
Molding
Pouring
into mold
Inspection
Cleaning &
Finishing
Heat
Treatment
t
Casting
Sand
Melting
of Metal
Mold

11. Ken Youssefi Mechanical Engineering Dept., SJSU
Sand Casting Process

12. Examples of Cast Parts

13. Advantages of Casting Process
● any intricate shape & shape can be cast, both internal & external
● any metal or alloy that can be heated to the liquid state can be
cast
● Is the easiest and quickest way from drawing to the production
● Some methods are highly suitable for mass production
● Some operations capable of producing parts to net shape require
no further machining
● rapid cooling provides small grain size and good strength to casting
Limitations of Casting Process
● Limitation on mechanical properties
● Poor dimensional accuracy and surface finish
● Removal of pattern of the thin & small parts is very difficult
● Safety hazards to humans & environmental problems
● Internal defects cannot be completely eliminated

14. Basic Terminology in Casting Process
● Mould (Mold or flask) - is essentially a negative of the
final product or having a cavity of the casting shape
which is to be manufactured, in which molten metal is
poured.
● Pattern - made of wood or metal, is a replica of the
final product and is used for preparing mould cavity.
● Core – is an obstruction (made of either sand or metal)
positioned in the mold does not permit molten metal to
fill space occupied by core, thereby making holes or
hollow cavities inside a casting.
● Mold Box – is a combination of two halves; upper half
is called cope and lower half drag.

15. ● Mold material – is one out of which mold is made,
must retain its shape till metal has solidified. Wax,
plaster of Paris, ceramics, etc. are some materials.
● Pouring cup - is a funnel shaped cup which forms
the top portion of sprue and allows operator to
direct flow of metal from crucible to sprue.
● Sprue – is a vertical channel ( square or round)
through which molten metal flows downward in
the mold and enters the runner & gate.
● Pouring basin – acts as a reservoir from which
molten metal moves smoothly into sprue, holds
back slag & dirt which floats on top.

16. ● Runner – channels that carry the molten metal
from the sprue to the mold cavity.
● Gate – is the portion of the runner through which
the molten metal enters the mold cavity; more
gates for large castings can be made.
● Riser – serve as reservoirs to supply the molten
metal necessary to prevent shrinkage, permits
escape of air & mold gases.
● Ladle – used to carry
molten metal from
the furnace to the
molding boxes.

17. Pattern and Mould

20. Steps involved in Casting Process
● Pattern Making
● Sand mixing & preparation
● Core making
● Melting
● Pouring
● Finishing
● Testing
● Heat Treatment
● Re-testing

21. Open and Closed Mould

22. Sand Casting