sand casting steps
Post on 04-Apr-2018
255 Views
Preview:
TRANSCRIPT
-
7/31/2019 Sand Casting Steps
1/30
SAND CASTING STEPS
-
7/31/2019 Sand Casting Steps
2/30
-
7/31/2019 Sand Casting Steps
3/30
-
7/31/2019 Sand Casting Steps
4/30
Advantages of sand casting
-
7/31/2019 Sand Casting Steps
5/30
Low cost of mold materials and equipment.
Large casting dimensions may be obtained.
Wide variety of metals and alloys (ferrous and non-ferrous) may be cast (including high
melting point metals).
Disadvantages of sand casting
Rough surface.
Poor dimensional accuracy.
High machining tolerances.
CoarseGrain structure.
http://www.substech.com/dokuwiki/doku.php?id=grain_structurehttp://www.substech.com/dokuwiki/doku.php?id=grain_structurehttp://www.substech.com/dokuwiki/doku.php?id=grain_structure -
7/31/2019 Sand Casting Steps
6/30
-
7/31/2019 Sand Casting Steps
7/30
This process takes advantage of the lowboiling point of foam to simplify the investment
casting process by removing the need to melt the wax out of the mold
http://en.wikipedia.org/wiki/Boiling_pointhttp://en.wikipedia.org/wiki/Boiling_pointhttp://en.wikipedia.org/wiki/Boiling_point -
7/31/2019 Sand Casting Steps
8/30
-
7/31/2019 Sand Casting Steps
9/30
LOST FOAM CASTING STEPS
-
7/31/2019 Sand Casting Steps
10/30
-
7/31/2019 Sand Casting Steps
11/30
-
7/31/2019 Sand Casting Steps
12/30
-
7/31/2019 Sand Casting Steps
13/30
For liner also the same procedure:
-
7/31/2019 Sand Casting Steps
14/30
Centrifugal casting
Centrifugal casting is a method of casting parts having axial symmetry. The method involves
pouring molten metal into a cylindrical mold spinning about its axis of symmetry.
The mold is kept rotating till the metal has solidified.
As the mold material steels, Cast irons, Graphite or sand may be used.
The rotation speed of centrifugal mold is commonly about 1000 RPM (may vary from 250 RPM to
3600 RPM).
A centrifugal casting machine is schematically presented in the picture:
Centrifugal casting process
Mold preparation
Pouring
Cooling
Casting removal
-
7/31/2019 Sand Casting Steps
15/30
Finishing
Mold preparation
The walls of a cylindrical mold are first coated with a refractory ceramic coating, which
involves a few steps (application, rotation, drying, and baking).
Once prepared and secured, themold is rotated about its axis at high speeds (300-3000
RPM), typically around 1000 RPM.
Pouring
Molten metal is poured directly into the rotating mold, without the use of runners or a
gating system.
The centrifugal force drives the material towards the mold walls as the mold fills.
Cooling
With all of the molten metal in the mold, the mold remains spinning as the metal cools.
Cooling begins quickly at the mold walls and proceeds inwards.
Casting removal
After the casting has cooled and solidified, the rotation is stopped and the casting can be
removed.
Finishing
While the centrifugal force drives the dense metal to the mold walls, any less dense
impurities or bubbles flow to the inner surface of the casting.
As a result, secondary processes such as machining, grinding, or sand-blasting, are
required to clean and smooth the inner diameter of the part.
http://www.substech.com/dokuwiki/doku.php?id=steels_and_cast_ironshttp://www.substech.com/dokuwiki/doku.php?id=cast_ironshttp://www.substech.com/dokuwiki/doku.php?id=graphitehttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/lib/exe/detail.php?id=centrifugal_casting&cache=cache&media=centrifugal_casting.pnghttp://www.substech.com/dokuwiki/doku.php?id=solidificationhttp://www.substech.com/dokuwiki/doku.php?id=steels_and_cast_ironshttp://www.substech.com/dokuwiki/doku.php?id=cast_ironshttp://www.substech.com/dokuwiki/doku.php?id=graphite -
7/31/2019 Sand Casting Steps
16/30
A cylinder liner is a
cylindrical part to be fitted into an engine block to form a cylinder.
Formation of sliding surface
The cylinder liner, serving as the inner wall of a cylinder, forms a sliding surface for
the piston rings while retaining the lubricant within.
-
7/31/2019 Sand Casting Steps
17/30
The most important function of cylinder liners is the excellent characteristic as sliding
surface and these four necessary points.
(1)High anti-galling properties
(2)Less wear on the cylinder liner itself
(3)Less wear on the partner piston ring
(4)Less consumption of lubricant
Bearing bushes
Piston bearings
-
7/31/2019 Sand Casting Steps
18/30
A piston ring is a split ring that fits into a groove on the outer diameter of apiston in
a reciprocating engine such as an internal combustion engineorsteam engine.
The three main functions of piston rings in reciprocating engines are :
Sealing the combustion/expansion chamber.
Supporting heat transfer from the piston to the cylinderwall.
Regulating engine oil consumption.
Fly wheel
-
7/31/2019 Sand Casting Steps
19/30
A flywheel is an inertial energy-storage device.
It absorbs mechanical energy and serves as a reservoir, storing energy during the period
when the supply of energy is more than the requirement and releases it during the period
when the requirement of energy is more than the supply
The Basic Permanent Mold Process
Permanent mold casting (gravity die casting) is a casting process involving pouring a molten
metal by gravity into a steel (orcast iron) mold.
The permanent mold casting is similar to the sand casting process . In distinction from sand molds,which are broken after each casting a permanent mold may be used for pouring of at least one
thousand and up to 120,000 casting cycles with the rate 5-100 castings/hour.
Manufacturing metal mold is much more expensive than manufacturing molds forSand
casting orinvestment casting process mold. Minimum number of castings for profitable use of a
permanent mold is dependent on the complexity of its shape.
Ferrous and no-ferrous metals and alloys are cast by the permanent mold casting
process: Aluminum alloys, Copper alloys, Magnesium alloys, zinc alloys, steels and Cast irons.
Permanent mold casting process
Design aspects of permanent mold casting
Advantages and disadvantages of permanent mold casting
http://en.wikipedia.org/wiki/Reciprocating_enginehttp://en.wikipedia.org/wiki/Pistonhttp://en.wikipedia.org/wiki/Reciprocating_enginehttp://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Steam_enginehttp://en.wikipedia.org/wiki/Cylinder_(engine) -
7/31/2019 Sand Casting Steps
20/30
Permanent mold casting process
The interior surfaces of the two parts (cope and drag) of a permanent mold are coated with
a thin ceramic coating. The mold is preheated before coating to 300-500F (150-260C).
The cores are inserted and installed in the mold assembly.
The mold is closed.
The molten metal is poured into the mold.
After the casting has solidified and cooled down to the desired temperature the mold is
opened and the casting is withdrawn from it.
The gating system is cut away from the casting.
The finish operations are carried out.
to top
Design aspects of permanent mold casting
Permanent molds are made ofCarbon steels, grey cast irons, Graphite (for
casting steels and Cast irons) orbronze.
Since the metallic mold of a permanent casting expands when it is filled with a molten
metal and then both the casting and the mold shrinks during cooling the shrinkage allowances
taken in the permanent mold design are smaller than those in the Sand casting.
External cooling (by water or air) may be used for creating desired solidification direction
and reducing shrinkage defects and internal stresses.
Parts of 0.4 lb (0.1 kg) to 150 lb (70 kg) may be cast.
The section thickness of permanent mold casting may vary in the range 0.1 - 2 (2.5-50
mm).
The dimensional tolerances are 0.015-0.06 (0.4-1.5 mm) depending on the casting section
thickness.
Allowances of 0.01-0.03 (0.25-0.75 mm) are taken for the dimensions crossing the parting
line of the mold.
The draft angle is commonly 1-3%.
Permanent cores are commonly used for permanent mold castings, however if a casting has
cavitys shape not allowing a withdrawal of the core it is made of chemically bonded sand or
other materials used for preparation of expendable cores. New consumable cores are added
http://www.substech.com/dokuwiki/doku.php?id=steels_and_cast_ironshttp://www.substech.com/dokuwiki/doku.php?id=sand_castinghttp://www.substech.com/dokuwiki/doku.php?id=sand_castinghttp://www.substech.com/dokuwiki/doku.php?id=investment_castinghttp://www.substech.com/dokuwiki/doku.php?id=aluminum_alloyshttp://www.substech.com/dokuwiki/doku.php?id=copper_alloyshttp://www.substech.com/dokuwiki/doku.php?id=magnesium_alloyshttp://www.substech.com/dokuwiki/doku.php?id=steels_and_cast_ironshttp://www.substech.com/dokuwiki/doku.php?id=sand_castinghttp://www.substech.com/dokuwiki/doku.php?id=sand_castinghttp://www.substech.com/dokuwiki/doku.php?id=sand_castinghttp://www.substech.com/dokuwiki/doku.php?id=investment_castinghttp://www.substech.com/dokuwiki/doku.php?id=solid_solutionshttp://www.substech.com/dokuwiki/doku.php?id=aluminum_alloyshttp://www.substech.com/dokuwiki/doku.php?id=copper_alloyshttp://www.substech.com/dokuwiki/doku.php?id=magnesium_alloyshttp://www.substech.com/dokuwiki/doku.php?id=steels_and_cast_ironshttp://www.substech.com/dokuwiki/doku.php?id=cast_ironshttp://www.substech.com/dokuwiki/doku.php?id=permanent_mold_casting#permanent_mold_casting_processhttp://www.substech.com/dokuwiki/doku.php?id=permanent_mold_casting#design_aspects_of_permanent_mold_castinghttp://www.substech.com/dokuwiki/doku.php?id=permanent_mold_casting#advantages_and_disadvantages_of_permanent_mold_casting -
7/31/2019 Sand Casting Steps
21/30
after each pour. The process combining permanent mold and consumable parts (cores) are
called semi-permanent casting.
to top
Advantages and disadvantages of permanent mold casting
Advantages of permanent mold casting process are determined by relatively high cooling rate
caused by solidification in metallic mold:
Bettermechanical properties.
Homogeneous grain structure and chemical composition.
Low shrinkage and gas porosity.
Good surface quality: 40-250 inch (1-6 m) Ra.
Low dimensional tolerances: typically about 0.04 (1 mm}.
Little scrap process.
Disadvantages ofpermanent mold casting:
High cost of the molds.
Limitations in casting of high melting point metals into metallic molds.
Intrinsic and complex shapes can not be cast.
Large parts can not be cast.
http://www.substech.com/dokuwiki/doku.php?id=solidificationhttp://www.substech.com/dokuwiki/doku.php?id=permanent_mold_castinghttp://www.substech.com/dokuwiki/doku.php?id=steels_and_cast_ironshttp://www.substech.com/dokuwiki/doku.php?id=cast_ironshttp://www.substech.com/dokuwiki/doku.php?id=copper_alloyshttp://www.substech.com/dokuwiki/doku.php?id=casting_properties#shrinkagehttp://www.substech.com/dokuwiki/doku.php?id=solidificationhttp://www.substech.com/dokuwiki/doku.php?id=permanent_mold_castinghttp://www.substech.com/dokuwiki/doku.php?id=carbon_steelshttp://www.substech.com/dokuwiki/doku.php?id=cast_ironshttp://www.substech.com/dokuwiki/doku.php?id=graphitehttp://www.substech.com/dokuwiki/doku.php?id=steels_and_cast_ironshttp://www.substech.com/dokuwiki/doku.php?id=cast_ironshttp://www.substech.com/dokuwiki/doku.php?id=copper_alloyshttp://www.substech.com/dokuwiki/doku.php?id=casting_properties#shrinkagehttp://www.substech.com/dokuwiki/doku.php?id=sand_castinghttp://www.substech.com/dokuwiki/doku.php?id=sand_casting -
7/31/2019 Sand Casting Steps
22/30
http://www.substech.com/dokuwiki/doku.php?id=permanent_mold_castinghttp://www.substech.com/dokuwiki/doku.php?id=metal_properties_and_testshttp://www.substech.com/dokuwiki/doku.php?id=grain_structurehttp://www.substech.com/dokuwiki/doku.php?id=casting_propertieshttp://www.substech.com/dokuwiki/doku.php?id=casting_properties -
7/31/2019 Sand Casting Steps
23/30
-
7/31/2019 Sand Casting Steps
24/30
Pressure Die Casting
Pressure die casting is a quick, reliable and cost-effective manufacturing process for production of
high volume, metal components that are net-shaped have tight tolerances. Basically, the pressure
die casting process consists of injecting under high pressure a molten metal alloy into a steel mold
(or tool). This gets solidified rapidly (from milliseconds to a few seconds) to form a net shaped
component. It is then automatically extracted.
Advantages of Pressure Die Casting :
Lower costs compared to other processes.
Economical - typically production of any number of components from thousands to
millions before requiring replacement is possible.
Castings with close dimensional control and good surface finish
-
7/31/2019 Sand Casting Steps
25/30
Castings with thin walls, and therefore are lighter in weight
High Pressure Die Casting
Here, the liquid metal is injected with high speed and high pressure into the metal mold. The basic
equipment consists of two vertical platens. The bolsters are placed on these platens and this holds
the die halves. Out of the two platens, one is fixed and the other movable.
High Pressure Die Casting Process
This helps the die to open and close. A specific amount of metal is poured into the shot sleeve and
afterwards introduced into the mold cavity. This is done using a hydraulically-driven piston. After
the metal has solidified, the die is opened and the casting eventually removed.
Types of High Pressure Die Casting:
http://www.rajshiindustries.com/pressure-die-casting.html -
7/31/2019 Sand Casting Steps
26/30
Both the processes are described below. The only difference between the two processes is the
method being used to inject molten metal into the die.
Hot Chamber Process
The hot-chamber process is applicable only for zinc and other low melting point alloys that does
not affect and erode metal pots cylinders and plungers.
The basic components of a hot-chamber diecasting machine and die are illustrated below:
Types of Pressure Die Casting
Depending upon the pressure used, there are two types of pressure die casting namely High
Pressure Die Casting and Low Pressure Die Casting. While high pressure die casting has
wider application encompassing nearly 50% of all light alloy casting production. Currently
low pressure die casting accounts for about 20% of the total production but its use is
increasing. High pressure castings are must for castings requiring tight tolerance and
detailed geometry. As the extra pressure is able to push the metal into more detailed
features in the mold. Low pressure die casting is commonly used for larger and non-critical
parts.
However, the machine and its dies are very costly, and for this reason pressure die casting
is viable only for high-volume production.
HOT CHAMBER DIE CASTING PROCESS
Hot chamber machines are used primarily for zinc, copper, magnesium, lead and other low
melting point alloys that do not readily attack and erode metal pots, cylinders and plungers.
The injection mechanism of a hot chamber machine is immersed in the molten metal bath
of a metal holding furnace.
The furnace is attached to the machine by a metal feed system called a gooseneck.
-
7/31/2019 Sand Casting Steps
27/30
As the injection cylinder plunger rises, a port in the injection cylinder opens, allowing
molten metal to fill the cylinder.
As the plunger moves downward it seals the port and forces molten metal through the
gooseneck and nozzle into the die cavity.
After the metal has solidified in the die cavity, the plunger is withdrawn, the die opens and
the casting is ejected.
COLD CHAMBER DIE CASTING PROCESS
Cold chamber machines are used for alloys such as aluminum and other alloys with high
melting points.
The molten metal is poured into a "cold chamber," or cylindrical sleeve, manually by a
hand ladle or by an automatic ladle.
-
7/31/2019 Sand Casting Steps
28/30
A hydraulically operated plunger seals the cold chamber port and forces metal into the
locked die at high pressures.
Low Pressure Die Casting
High quality castings, of aluminium alloys, along with magnesium and other low melting point
alloys are usually produced through this process. Castings of aluminium in the weight range of 2-
150 kg are a common feature.
The process works like this, first a metal die is positioned above a sealed furnace containingmolten metal. A refractory-lined riser extends from the bottom of the die into the molten metal.
Low pressure air (15 - 100 kPa, 2- 15 psi) is then introduced into the furnace. This makes the
molten metal rise up the tube and enter the die cavity with low turbulence. After the metal has
solidified, the air pressure is released . This makes the metal still in the molten state in the riser
tube to fall back into the furnace. After subsequent cooling, the die is opened and the casting
-
7/31/2019 Sand Casting Steps
29/30
extracted.
With correct die design it is possible to eliminate the need of the riser also. This is because of the
directional freezing of the casting. After the sequence has been established, the process can be
controlled automatically using temperature and pressure controllers to oversee the operation of
more than one diecasting machine.
Casting yield is exceptionally high as there is usually only one ingate and no feeders.
Low Pressure Die Casting Process
Application of Pressure Die Casting
Automotive parts like wheels, blocks, cylinder heads, manifolds etc.
Aerospace castings.
Electric motor housings.
Kitchen ware such as pressure cooker.
-
7/31/2019 Sand Casting Steps
30/30
Cabinets for the electronics industry.
General hardware appliances, pump parts, plumbing parts.
top related