Mastering the art of patterns and its making in the field of manufacturing

1. PATTERN AND
PATTERN MAKING

2. Introduction
Introduction
A pattern is a mold forming tool in the hands of
foundary men


A pattern is a model or the replica of the object to be
cast.


Except for the various allowances a pattern exactly
resembles the casting to be made.


A pattern is required even if one object has to be cast.


A pattern may be defined as a model or form around
which sand is packed to give rise to a cavity known as
mold cavity in which when, molten metal is poured,
the result is the CAST OBJECT.

3. FUNCTION OF PATTERNS
FUNCTION OF PATTERNS
A pattern prepares a mold cavity for the purpose of making a casting.


A pattern may contain projections known as core prints if the casting
requires a core and need to be made hollow.


Runner, gates and risers (used for introducing and feeding molten metal
to the mold cavity) may form a part of the pattern.


A pattern may help in establishing locating points on the mold and
therefore on the casting with a purpose to check the casting dimensions.


Patterns establish the parting line and parting surfaces in the mold.


A pattern may help position a core (in case a part of mold cavity is made
with cores), before the molding sand is rammed.


Patterns that are properly made and having finished and smooth surfaces,
reduce casting defects.


Properly constructed patterns minimize overall cost of the castings.

4. PATTERN MATERIAL
PATTERN MATERIAL
The following factors assist in selecting proper pattern material:


The number of castings to be produced. Metal patterns are
preferred when the production quantity is large.


The desired dimensional accuracy and surface finish required
for the castings.


Nature of molding process i.e., sand casting, permanent mold
casting, shell molding, investment casting etc.


Method of molding i.e., hand or machine molding.


Shape, complexity and size of the casting.


Type of molding materials i.e., sand etc.


The high probability of changing the casting and hence the
pattern in near future.

5. Materials for making patterns
Materials for making patterns
1.Wood
2.Metal
3.Wax
4.plastic
5.Plaster(POP)
1.Wood
2.Metal
3.Wax
4.plastic
5.Plaster(POP)

6. • The most common materials for making patterns for sand casting is the wood.
ADVNTAGE


Inexpensive.


Easily available in large quantities.


Easy to machine and to shape to different configurations and forms


Easy to join to acquire complex and large pattern shapes


Light in weight


Easy to obtain good surface finish


Wooden patterns can be preserved for quite long times with the help of suitable wood preservatives.
Limitations


Wooden patterns are susceptible to shrinkage and swelling.


They possess poor wear resistance.


They are abraded easily by sand action.


They absorb moisture, consequently get deformed and change shape and size.


They cannot withstand rough handling.


They are weak as compared to metal patterns.

7. Metal Patterns


Metal patterns are employed where large number of castings have
to be produced from the same patterns.


Metal patterns are cast from wooden patterns.


The different metals and alloys used for making patterns are,


Aluminium and Aluminium alloys


Steel


Cast Iron


Brass


White Metal

8. Plastic Patterns
Advantages


Moisture resistant.


A plastic pattern does not involve any appreciable change in its size or shape.


Lightweight.


Wear and corrosion resistant.


Provides good surface finish.


It possesses low solid shrinkage.
Limitations


Plastic patterns are fragile and thus light sections may need metal reinforcements.


Plastic patterns may not work well when subject to conditions of severe shock as in
machine moulding.
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9. Plaster (POP) Patterns
Advantages


can be easily worked by using wood working tools.


Intricate shapes can be cast without any difficulty.


It has high compressive strength (up to 285 kg/cm?)
Disadvantages


Can be used for small castings only


Plaster Patterns Material: Plaster patterns may be made out of Plaster of
Paris or Gypsum cement.


Applications: Plaster is used for making (i) Small and intricate patterns,
and (ii) Core boxes.

10. Wax Patterns


Advantages


Wax patterns provide very good surface finish
They impart high accuracy to the castings.
After being molded, the wax pattern is not taken
out of the mold like other patterns; rather the
mold is inverted and heated; the molten wax
comes out and/or is evaporated. Thus there is no
chance of the mold cavity getting damaged while
removing the pattern


Applications


Wax patterns find applications in Investment Fig-Lost Wax Technique

11. For selecting a particular kind of pattern for making a
casting, one may consider the following points:
Quantity of castings to be produced.


The size and the complexity of the shape of the casting to be produced.


Type of molding method to be used (i.e., hand or machine molding).


Problems associated with the molding operation such as withdrawing the pattern
from the mold etc.


Other difficulties resulting from poor casting design or pattern design
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15. Conclusion
Conclusion
Mastering pattern making requires an understanding of key
principles such as body measurements, ease, and grainline,
as well as techniques like draping and flat pattern making.
With practice, you can create patterns that fit well and look
flattering. This skill can lead to unique designs and a better
fitting wardrobe.
Mastering pattern making requires an understanding of key
principles such as body measurements, ease, and grainline,
as well as techniques like draping and flat pattern making.
With practice, you can create patterns that fit well and look
flattering. This skill can lead to unique designs and a better
fitting wardrobe.

16. Thanks!
Thanks!
Do you have any questions?
addyouremail@freepik.com
+91 620 421 838
yourcompany.com
Do you have any questions?
addyouremail@freepik.com
+91 620 421 838
yourcompany.com