Advantages and Disadvantages of Different Casting Processes

CASTING PROCESSES

Advantages & Disadvantages

Taha Mustahsan

Roll #: 14

Reg #: 2008-UET-IEFR-MECH-FD-08

Submitted to: Sir Syed Amjad Ahmed

Casting Processes | Advantages & Disadvantages

1

ADVANTAGES AND DISADVANTAGES OF DIFFERENT CASTING PROCESSES

PRESSURE DIE CASTING

Advantages Disadvantages

1. High speed production can be achieved as

the whole process is completely

automated.

2. Possible to obtain fairly complex castings

than that feasible by gravity die casting due

to the use of the movable cores.

3. Very small thicknesses can be easily filled as

the liquid metal is injected under high

pressure.

4. Very good surface finish can be obtained &

most of pressure die castings can be

directly electroplated without any further

processing.

5. Closer dimensional tolerances & better

mechanical properties can be obtained

compared to sand casting.

6. Very economical for large scale production.

1. Large capital investment is required to

set up a pressure die casting process.

2. The die casting machines & tooling

costs are very expensive.

3. Cannot be used for large castings as

the casting machine capacity is limited.

4. It is not suitable for all materials

because of the limitations of the die

materials & the alloys used must have a

low melting point.

5. High porosity is common & heat

treatment is difficult.

APPLICATIONS

Automotive parts like wheels, blocks, cylinder heads, manifolds etc.

Aerospace castings.

Electric motor housings.

Kitchen ware such as pressure cooker.

Cabinets for the electronics industry.

General hardware appliances pump parts, plumbing parts.

http://www.themetalcasting.com/pressure-die-casting.html


2

INVESTMENT CASTING


1. Complex shapes which are difficult by

any other method are possible.

2. Very close tolerances and excellent

surface finish can be obtained.

3. Ready for use with little or no

machining required.

4. Almost any metal can be cast.

5. No flash or parting lines.

6. Suit for producing complex shapes

where other manufacturing processes

are too costly and time-consuming.

1. Time consuming as shell molds cannot

be reused.

2. Expensive as many labor involved in

the preparation of the wax patterns &

shell molds.

3. The size of the casting is often limited.

4. Occasional minute defects.

APPLICATIONS

Typically materials that can be cast with this process are Aluminum alloys,

Bronzes, Stainless steels, Satellite etc. Glass mold accessory castings, Valves and fittings,

Gears, Levers and Splines are some of the popular usages.

LIMITATIONS

Time consuming process and costly. Exceptional surface finish possible but minute lacuna

can cause rejection of castings as a result scrap rates can be high.

http://en.wikipedia.org/wiki/Flash_(manufacturing)

http://en.wikipedia.org/wiki/Parting_line


3

SAND CASTING


1. Low capital investment means that

short production runs are viable.

2. Use of sand cores allows fairly complex

shapes to be cast.

3. Large components can be produced.

4. Suitable for small batch production

(small production rates).

5. It is a quick process.

6. All kind of metals can be used in sand

casting process.

7. There is no size limit.

1. The process has a high unit cost, as it is

labor intensive and time consuming.

2. The sand mold leaves bad surface

finish.

3. Further machining process is required.

4. We cannot make thin sections.

5. Not suitable for mass production.

6. Scrap metal increased.

7. Poor material strength.

APPLICATIONS

Sand casting process is used to make

Engine blocks,

Gear blanks

Crankshafts

Brake drums

Fan blades

Tubes etc.


4

PLASTER MOLD CASTING


1. Smooth "As Cast" finish (25 RMS)

2. Closer dimensional tolerance than

Sand Casting

3. Intricate shapes and fine details

including thinner "As Cast" walls are

possible

4. Large parts cost less to cast than by

Investment process

1. More costly than Sand or Permanent

Mold-Casting

2. Limited number of sources

3. Requires minimum of 1 deg. draft

APPLICATIONS

It can be used for making quick prototype parts as well as limited production parts.

LIMITATIONS

Poor productivity as it has lengthy processing problems.

Close monitoring of the production process.

The problems of poor mold permeability.

Impaired mechanical properties a possibility as a result of slow cooling of the casting.


5

CENTRIFUGAL CASTING


1. Relatively very light impurities move

inwards towards center. So they can be

removed easily thus helping in

producing sound castings.

2. These castings have a directional

solidification starting from outside to

inside.

3. Central core is not required for making

a hole or pipe

4. Employment of gates and risers is not

required

5. This technique is best suited for the

mass production of symmetrical

objects.

6. Castings yield is very high in some

cases it is even equal to 100%

1. Centrifugal castings require very high

investments.

2. Skilled labors are to be employed for

this process.

3. Only some shapes can be generated by

this casting process.

Applications

Bearings for machines

Pipes

Liners for IC engines

Rings and other annular components

Wheels nozzles and similar parts.


6

DIE CASTING


1. Good dimensional tolerances are

possible

2. Excellent part-part dimensional

consistency

3. Parts require a minimal post machining

4. The process is more economical and

efficient.

5. It offers a large range of shapes and

components than any other

manufacturing process.

1. Economical only in very large

quantities due to high tool cost

2. Not recommended for hydrostatic

pressure applications

3. For Castings where penetrant (die) or

radiographic inspection are not

required.

4. Difficult to guarantee minimum

mechanical properties

LOST FOAM CASTING


1. It is dimensionally accurate, maintains

an excellent surface finish and has no

parting lines so no flash is formed.

2. As compared to investment casting, it is

cheaper because it is a simpler process

and the foam is cheaper than the wax.

3. Foam is easy to manipulate, carve and

glue, due to its unique properties.

4. The flexibility of LFC often allows for

consolidating the parts into one

integral component.

1. The pattern costs can be high for low

volume applications and the patterns

are easily damaged or distorted due to

their low strength.

2. If a die is used to create the patterns

there is a large initial cost.

Application

Lost foam casting is used mostly for automotive applications.

http://www.themetalcasting.com/casting-process.html

http://en.wikipedia.org/wiki/Flash_(manufacturing)


7

PERMANENT MOLD CASTING


1. Less expensive than Investment or Die

Castings.

2. Dimensional Tolerances closer than Sand

Castings.

3. Castings are dense and pressure tight.

1. Only non-ferrous metals may be cast by this

process.

2. Less competitive with Sand Cast process

when three or more sand cores are

required.

3. Higher tooling cost than Sand Cast.

APPLICATIONS

Products include gears, splines, wheels, gear housings, pipe fittings, fuel injection housings, and

automotive engine pistons.

MOLD CASTING


1. It has better surface finish

2. It has better dimensional tolerances.

3. Machining process is reduced.

4. Less foundry space required.

5. Semi-skilled operators can handle the

process.

6. The process can be mechanized.

1. The raw materials are relatively expensive.

2. The process generates noxious fumes

which must be removed.

3. The size and weight range of castings is

limited.

APPLICATION

The applications of mold casting might be

Crankshaft fabrication

Steel casting parts

Molded tubing fabrication

Hydraulic control housing fabrication

http://www.themetalcasting.com/permanent-mold-cast.html

Documents

Advantages and Disadvantages of Different Casting Processes