The document discusses the casting process for hydraulic cylinder pistons. It begins by introducing pistons and their use in hydraulic mechanisms. It then describes the casting process, noting that large pistons are typically gravity die cast while smaller pistons may be sand cast. The casting process involves pouring molten metal into a mold. Further processes include lathe work to machine diameters and faces and milling holes. Pistons are widely used in engines and hydraulics.

1. Casting of

2. Introduction
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Hydraulic cylinder piston is used in
mechanism.
hydraulic
It is used to separate the pressure zones inside the
barrel.
Piston is machined with grooves to fit elastomeric or
metal seals and bearing elements.
Difference in pressure between the two sides of the
piston causes the cylinder to extend and retract piston.
It is attached with the piston rod by means of threads,
bolts, or nuts to transfer the linear motion.
Hydraulic cylinder piston

3. Processes on Piston

4. Casting
On large Scale
• The majority of original equipment and aftermarket pistons are manufactured through
casting.
• The technical description is 'gravity die casting'. However for the sake of simplicity, a cast
piston is manufactured by pouring molten metal into a mold to make the rough layout of
piston.
• There are traces of many other metals in cast pistons, including copper, nickel, manganese and
magnesium, all of these adding somewhat to the overall behavior and strength of the piston.
• Piston made by casting has some allowance to perform further processes on it.
Small Industries
• On small scale where production is low sand casting is used as it is the cheap.
• Other benefit of it is that the pattern is reused that reduces the marked cost of the part.

5. Foundry
A foundry is a small
factory that produces
metal castings.Metals
are cast into shapes
by melting them into
a liquid, pouring the
metal in a mold, and
removing the mold
material or casting
after the metal has
solidified as it cools.

6. Sand Casting
Place
a pattern in
sand to
create a
mold.
Break away
the sand
mold and
remove the
casting.
Incorporate
the pattern
and sand in a
gating
system.
Allow the
metal to
cool.
Remove the
pattern.
Fill the mold
cavity with
molten
metal.

7. Pattern
• Before casting mold is prepared by using the pattern,
pattern may be permanent or temporary i.e. made of
plastic or rubber
• In our case its permanent.
Pattern
Bonding agent
• A suitable bonding agent (usually clay) is mixed or
occurs with the sand.
• The mixture is moistened, typically with water,
but sometimes with other substances, to develop
strength and plasticity of the clay and to make the
aggregate suitable for molding
Bonding agent

8. Mold
• As the part is simple in shape, sand
mold is used as it is cheap.
• Different molds are used time to time.
mold

9. Electric furnace
Manual furnace (coal is
used )

10. The Process
• The process starts by heating the material to 1200
degrees Celsius.
• This is well above the melting point of the metal,
but below its boiling point.
• The material is then scooped up with a ladle from
the crucible (the pot that holds the molten
material).
• This is then poured into the mold through the
spruce. The material is then allowed to cool before
it is removed from the mold and placed into a bin of
hot water.
• This water is used to facilitate a more even settling
of the hot metal.
• After the castings have had time to cool.
• This process tempers the casting and ensures the
piston will have improved qualities.
Molten metal

11. Lathe Process
The casted piston is taken to the lathe machine for further processes. The following processes are
done on piston on lathe;
Turning
The piston is set in the jaws of lathe and set to rotation. The turning is the process in which the
diameter of the piston is reduced. The required diameter of piston is determine in this process. This
process is also used for the polishing of the piston.
Facing
The piston is set in the jaws of lathe and set to rotation. In facing the length of the piston is
reduced. The require length of piston is set in this process.
Other operation
The additional lines for the Rings of piston which are shown on the figure which are seen on
the piston are also done on lathe machine.

12. Turning , facing on the lathe

13. Milling operation
The other shape which needed on the piston which can’t be made on the lathe machine is made
with the help of milling machine. Like the hole for the connecting pin which connects the piston
with piston rod is made by the Milling machine.
Polishing
The sides of the piston are highly
polished to reduce the friction. This
process can be done by rubbing sand
papers on the piston. For high
polished surface piston are placed on
the lathe machine and then the sand
paper are used as the tool to polish the
surface of piston as shown in the
figure.

14. Uses
• Pistons are widely used in the engines of
automobiles, Ships, etc.
•
It is used with hydraulics for the lifting purpose.
• The main function of the piston is to separate the
pressure zones inside the barrel.