Core and core prints and types of cores by polayya chintada

1. Production Technology:
CORE AND TYPES OF CORES
COURSE CODE: C211
REGULATION: R19
2nd BTECH 2nd SEM
PREPARED BY :
POLAYYA CHINTADA M.TECH,M.B.A,(PhD)
ASSISTANT PROFESSOR
LENDI INSTITUTE OF ENGINEERING AND
TECHNOLOGY

2. 2
PRODUCTION TECHNOLOGY
SYLLABUS
UNIT 1:
Introduction: Importance and selection of manufacturing processes.
Casting Processes: Introduction to casting process, process steps; pattern: types, materials
and allowance; Cores: Types of cores, core prints, principles and design of gating system;
Solidification of casting: Concept, solidification of pure metal and alloy; Special casting
processes: Shell casting, investment casting, die casting, centrifugal casting, casting defects
and remedies.
provide insight into Working
principles of different metal casting
processes and gating system
COURSE OBJECTIVE:
COURSE OUTCOMES:
Explain different metal
casting processes and
gating systems. (L2)
APPLICATIONS:
Identify different patterns and
their allowances (L3)
1. Heavy Equipment : Construction,
farming and mining
2. Defence : Vehicles, artillery,
munitions, storage and supporting
equipment
3. Hardware : Plumbing industry
pipes, joints, valves and fitting
Identify the various casting
defects. (L3)

3. CORE
• Core can be made by sand +binder+water
• The shape of the core depends on to the shape of the internal feature to
obtained
• Core is metal or sand body, which is set into the prepared mould before
closing or pouring it .
• These are used to produce holes, projections, cavities in casting.
• Cores are used where some shapes cant be produced by pattern
• core as a sand shape is generally produced separate from the sand mold and
is then baked (hardened) to facilitate handling and setting into the mold.
• Cores may be made up of sand, metal, plaster or ceramics.
• Cores are used in sand molding as well as permanent molding
• core is kept on seat in the mould box prepared by pattern.

4. EXAMPLES OF CORE AND ITS PRODUCTS

5. CORE FUNCTIONS & CHARACTERISTICS
Different Functions (Purposes) of Cores
• For hollow castings, cores provide the means of
forming the main internal cavities.
• Cores may provide external undercut features
• Cores may be employed to improve the mold
surface
• Cores may be inserted to achieve deep recesses in
the castings.
• Cores may be used to strengthen the molds
• Cores may be used to form the gating system of large
size molds.
• A Core must possess
– Sufficient strength to support itself and to get handled
without breaking.
– High permeability to let the mold gases escape through
the mold walls.
– Smooth surface to ensure a smooth casting.
– High refractoriness to withstand the action of
hot molten metal (metal penetration etc.).
– High collapsibility in order to assist the free
contraction of the solidifying metal.
Characteristics of (dry sand) Cores

6. TYPES OF CORES
Cores may be classified
according to
A. The state or condition of core
1. Green sand core
2. Dry sand core
B. The nature of core materials
employed
1. Oil bonded cores
2. Resin bonded cores
3. Shell cores
4. Sodium silicate cores
D. The shape and position of the core
1. Horizontal core
2. Vertical core
3. Hanging or cover core
4. Balanced core
5. Drop core or stop off core
6. Ram up core
7. Kiss core.
C. The type of core hardening process employed
1. The hot box process
2. The cold set process
3. Fluid or cast able sand process
4. Furan-No-Bake system
5. Oil-No-Bake process

7. Green sand cores
• Green sand cores are formed by the pattern
itself.
• A green sand core is a part of the mold.
• A green sand core is made out of the same
sand from which the rest of the mold has
been made i.e., the molding sand.
DIS ADVANTAGE S
• Lack of strength
• Difficult to make long narrow core features

8. Dry sand cores
• Dry sand cores (unlike green sand cores )are not produced as a part
of the mold.
• Dry sand core are over come some of the dis advantages of green
sand core
• Dry sand cores are made separately and independent of the mold.
• A dry sand core is made up of core sand which differs very much
from the sand out of which the mold is constructed.
• A dry sand core is made in a core box and it is baked after ramming.
• A dry sand core is positioned in the mold on core-seats formed
by core-prints on the patterns.
• A dry sand core is inserted in the mold before closing the same.

9. Horizontal core
• Fig. shows horizontal core.
• A horizontal core is positioned horizontally in the mold.
• A horizontal core may have any
shape, circular or of some other
section depending upon the shape
of the cavity required in the casting.
• A horizontal core is supported in core seats at both ends.
• Uniform sectioned horizontal cores are generally placed
at the parting line.
• A horizontal core is very commonly used in foundries.

10. Vertical core
• Fig. shows a vertical core.
• On the cope side, a vertical core needs more taper so as not
to tear the sand in the cope while assembling cope and
drag.
• A vertical core is named so because
it is positioned in the mold cavity
with its axis vertical.
• The two ends of a vertical core are supported in core seats
in cope and drag respectively.
• A big portion of the vertical core usually remains in the
drag
• A vertical core is very frequently used in foundries.

11. Hanging or cover core
• Fig. shows a hanging (cover) core
• It is known as hanging core because it hangs;
it is also called cover core if it covers the
mold and rests on a seat made in the drag.
• A simple hanging core is one which is not
supported on any seat rather it hangs from
the cope with the help of wires, etc.
• A hanging core is supported from above and it hangs vertically in the mold cavity.
• A hanging core has no support from bottom.
• A hanging core is provided with a hole through which molten metal reaches
the mold cavity.
• Hanging cores can be made up of either green or dry sand.

12. Balanced core
• Fig. shows a balanced core.
• A balanced core is one which is supported and
balanced from its one end only.
• only blind holes or holes which are open at one
side are produced by balanced casting.
• A balanced core requires a long core seat so that
the core does not sag or fall
into the mold.
• A balanced core is used when a casting does not
want a through cavity.

13. Drop or stop off core
• Fig. shows a Drop or stop off core.
• A stop off core is employed to make a cavity (in the
casting) which cannot be made with other types of
cores.
• A stop off core is used when a hole, recess or cavity,
required in a casting is not in line with the parting
surface, rather it is above or below the parting line
of the casting.
• Depending upon its shape and use, a stop off core
may also be known as tail core, saddle core, chair
core, etc.

14. Yours:
POLAYYA CHINTADA M.TECH,M.B.A,(PhD)
ASSISTANT PROFESSOR