Design for casting and weldments design of casting

1. DESIGN FORCASTING
ANDWELDMENTS
M. SANTHOSH 2021507312
N.GOKULAKANNAN 2021507313
B.S.VENU GOPAL 2021507314

2. Welding
Machine
A welding machine is used to create the
heat and apply the filler metal. The filler
metal is supplied to form the joint, either
from the electrode itself (or) by
filler material. The temperature of the heat
produced is of the order of 6000° to
7000°c.

3. Types of
Welding
Processes
1.MIG welding
2.TIG welding
3.Stick welding
4.Flux cord arc welding
5.Plasma Arc welding
6.Electron beam welding
7.Laser beam welding
8.Gas welding
9.Automic hydrogen welding
10.Electroslag welding

4. WELD
DESIGN
RECOMMEND
ATION
Cost Reduction
Minimizing Distrotion
Weld Strength

5. COST
EDUCTION
Reduce no of weld parts
Easy to Access weld joints
Provide minimum amount of weld

6. Provide
minimum
amount of weld
Define, stack weld,
intermitten weld
( if the application doesn’t
involve high stress or leak
proof)

7. DESIGNER
SHOULD
AWAREOF
POORAND
GOOD FITUP
PARTS

8. Minimizing
Distortion
Use good Fitup to minimize weld time,
control distortion

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Weld gap should be as per standard
Use thicker component to reduce weld
distortion
Use short flange to reduce distortion

10. Continue…
Weld
flange

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12. Design for
solder and
brazed
assembly
 One of the most common joining processes,
Brazing, works on the principle of capillary action.
 It uses a filler metal that is melted and distributed
between the faying surfaces by capillarity.
 The process ensures that only the filler metal melts
and the base metals are unaffected.
 This is because the filler metal has a melting
temperature lower than that of the base metal that is
to be joined.

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The most common brazing metals are alloys of silver or of copper.
Filler metals of these materials have a melting point greater than
425°C.
Following are some of the heat sources via which the filler metal is
melted :
Heated iron (solder only)
 Gas torch
 Furnace
 Induction coils
 Dipping in either molten filler metal or a molten salt bath
 Electrical resistance (of the work piece itself)
 Infrared lamps

14. Brazing has
several
advantages
over welding.
These are
 Any metal including dissimilar metals can be
joined
 Thin wall parts that cannot be welded can be
brazed
 Less heat and power required than that in
fusion welding
 As the working temperature is low, problems
in the heat affected zone in the base metal are
reduced
 Joint areas that are inaccessible by many
welding processes can be brazed

15. Some
disadvantage
s and
limitations of
brazing
include
o Joint strength is less as compared to that in a
welded joint.
o Joint strength is less than that of the strength of
the base metal.
o The brazed joint is weakened by high service
temperatures.
o Sometimes color of the brazed surface and base
metals are dissimilar

16. Uses of the
Brazing
process
Some of the industries that use brazing on a
large enough scale include automotive
(joining tubes and pipes), electrical
equipments (joining wires and cables),
cutting tools (brazing cemented carbide
inserts to shanks), and jewelry marking
industries.

17. Soldering
Somewhat similar to brazing, soldering is a
joining process in which the filler metal has a
melting point less than 4250C and is melted and
distributed by capillary action between the faying
surfaces of the metal parts being joined. The filler
metal is called solder and is added to the joints,
which distributes itself between the closely fitting
parts.
Common materials which act as solders are based
on lead and tin (for higher temperatures) or on
brass and silver. Details of soldering are similar
to brazing.

18. Advantage
Low energy input relative to brazing and
welding
Variety of heating methods available
After soldering the joint has good
electrical and thermal conductivity.
Capable of making air-tight and liquid
tight seams for containers
Rework and repair are easy.

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Disadvantage :
Low joint strength unless reinforced by
mechanical means
 Possible weakening or melting of the joint
in elevated temperature service
Application :
Wide applications in the electronics
industry.
Used for mechanical joint but not for joints
subjected to elevated stresses or
temperature

20. TYPICAL
CHARACTERISTICS
Usually brazed and soldered assembly types are
recommended if either the configuration with single piece
is not possible or it is not economical to make from a
single piece. Such situation arises when:
Metals are dissimilar
The requirement is an intricate lightweight assembly
Machining is not feasible on parts that are very thin and
that have a high chance of breakage
Faced with leak proof joints of hollow shapes such as
tanks, floats and evaporators

21. SUITABLE
MATERIALS
 Various forms of solders available are - bar, wire (solid
or flux-cored) and paste forms.
 Solderable metals in the order of decreasing
solderability are listed below.
 1. Tin 2. Cadmium 3. Silver
 4. Copper 5. Brass 6. Bronze
 7. Lead 8. Nickel 9. Monel
 10. Zinc 11. Steel 12. Inconel
 13. Stainless steel 14. Chromium
15. Nichrome 16. Silicon bronze
17. Alnico 18. Aluminum

22. DETAILED
DESIGN
RECOMMEN
DATIONS
Joint Design :
Lap joint is the recommended form for these assemblies.
Generally, the area of overlap in the joint is kept large in
order to make it stronger than the weakest member of the
assembly.
A common thumb rule: Allow an overlap of at least three
times the thickness of the thinnest member.
The clearance between the joint surfaces varies from 0.025 to
0.20 mm with an average value of about 0.10 mm and usually
depends on the fluidity of the filler metal.

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Assembly :
 Parts considered for brazed assemblies process
are designed for easy assembly. The most
economical soldered and brazed assemblies are
those that are self-jigging, i.e., the assembled parts
and the filler metal hold together during the heating
cycle without any external fixture.
 The approaches involved for holding parts together
are gravity, spot and tack welding, friction and
press fits, staking and peening, swaging, crimping
and forming, threading, and riveting. These
methods have been illustrated

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Placement of Braze Metal :
 Metals used for soldering and brazing can be in
a number of forms namely, wire (commonly
formed into rings for circular joints), slugs,
shims, paste and sprayed or plated coatings and
these permit pre-placement before heating.
Sprayed or plated coatings are especially
applicable to copper brazing.

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1. If filler metal is in shims, the assembly should
be such that the parts are free to move when the
filler metal melts. This allows a stronger, narrow-
gap joint
2. One of the ways of avoiding gas entrapment in
joints is to provide a vent hole in the joint.