Transcript Practical Assesment for WCIF Foundry Technology Diploma

WCIF/AF Presentation
Gershwin van Harte
Atlantis Foundries, 16.10.2007
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Practical Assesment for WCIF
Foundry Technology Diploma
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• Hi! I am Gershwin van Harte
• Started at Atlantis Foundries on the 2nd of
February 2002
• I am currently working in the Melting
Department
Why am I doing the WCIF Courses?
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• To get a better knowledge of what I am
working with and the environment and to
know the product that I am producing
• To produce a good product at the end of
the day from the knowledge I gained from
the courses
• To uplift me in the workplace and strive
towards gaining opportunities at Atlantis
Foundries
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Introduction
WCIF Courses that I have done
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Cores & Core Making
Moulding & Moulding Sands
Fettling & Fettling Techniques
Supervisory Management
Production & Planning
Melting & Metallurgy
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Coremaking/Coreshop
Cured cores
Location cores
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The cores that I made was as
follow:
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Step 1: The wet-sand mix is prepared
by mixing sand with the two component
liquid and resin binder
Generally batch mixers are used
because it is more efficient and develop
greater core and tensile strength
Step 2: Sand was put in corebox and
tightly rammed
Step 3: Box was vented by putting a
rod through the center of the corebox
up to the other side
Step 4: The catalyst gas aimine
entered the corebox through the
ventalation hole and passes through the
core causing almost instantaneous
hardening of the resin coated sand
Step 5: The core was ready for
ejection from the corebox after
knocking it slightly with hammer
Good core compaction obviously benefits
casting surface quality and also
signifincantly improves core tensile
strength
Batchmixer
Amine machine
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Amine
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There is two kinds of gas catalyst mainly DMEA and TEA
At Atlantis Foundries we are using DMEA
Why DMEA?
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Cure cores faster than TEA
Characteristics of Amine
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It has a fishy odour
Extremely flammable
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Avoid skin contact
Avoid getting into eyes
High exposure causes blurred vision
Precautions
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Moulding/Cold Box Process
1 It is not dependent on any heat
sources for curing
4 It works well with all cast
metals
2 The process is less labour
intensive,therefore cheaper
3 The process can be used for
both core and mould production
5 Moulds are ejected from
the box fully cured and
dimensionally accurate
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6 The binders provide a flowable
sand mix that is easily
“rammed” and be used with
wood, metal or plastic tooling
8 Produces sound castings
with good surface finish, no
gas defects and low metal
penetration.
7 Designed for excellent castings
with good shake-out properties
in all metals
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9 It is permeable. If gasses doesn’t
escape properly it can cause mould
explosions
11 It possesses refractoriness to
withstand the high temperature
involved without melting and
fusing of sand grains
10 It has dry strength to prevent
erosion by liquid metal during
pouring
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Metallurgy/Melting Department
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What is the process of metal melting?
• Producing liquid metal at required rate and composition
• At required amount of super heat, at minimum cost
• Types of melting furnaces
Induction furnaces:
Examples ABB’s & VIP at Atlantis Foundries
After 250 heats it is relined
Most popular for grey cast iron
Pressure pour furnace:
This is were all castings are cast as per specification e.g. pouring
temperature, pouring time and slag free
Every year it is relined
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What is the process of metal melting?
We at Atlantis Foundries are
making use of induction
furnaces
Advantages:
•Precise controlled composition
of base liquid metal
•Can use a wide range of charge
materials
•Environmental Friendly
•Higher melting rate because of
stirring effect
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What is the process of metal melting?
Channel furnace/holding
furnace
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There are 3 furnaces at Atlantis
Foundries that holds 50 tons of
Molten metal each
This is not a Melting furnace but
a storage place for liquid metal
Precise control of temperatures
Every second year it is relined
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Factors that will cause a lining to fail
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Thermal design
Mechanical design
Chemical damage
Material selection
Anchoring failure
Installation
Commissioning
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Raw materials
Types
Returns
Steel scrap
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Raw materials
Coils
Snippers
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Ferro Alloys
Fe Cr
Fe S
Fe Mn
Fe Si
Carburiser/
Carbon
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Typical Furnace charge as per work
instruction at Atlantis Foundries
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Returns
Scrap blocks
Steel scrap
Snippers
Bails
Coils
Pig iron
2000 kg
2000 kg
1000 kg
1500 kg
1500 kg
1000 kg
1000 kg
Total =
10 000 tons
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The Casting
After knock out
After shot
blast
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Melt Quality Control Test that
was done
• Wedge chill test
• Temperature: 1460 degrees
• Pouring time: plus + 5 sec
• Chemical composition
• Spectrometer machine
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The results of the spark analysis of that day was as follow:
Actual Result Of Test
Specification for 460 block
Carbon
3.25
Carbon
3.25/3.30
Silicon
2.06
Silicon
2.00/2.08
Manganese
0.66
Manganese
0.60/0.68
Phosphorus 0.013
Phosphorus 0.005 Max
Sulphur
0.090
Sulphur
0.085/0.090
Chromium
0.22
Chromium
0.22/0.24
Alumimium
0.006
Alumimium
0.005 Max
Copper
0.19
Copper
0.40/0.50
Titanium
0.010
Titanium
0.012
Lead
0.002
Lead
0.005
Tin
0.070
Tin
0.070/0.080
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Design of gating system/runner system
Ingate
Runner bar
Runner system
before cutting
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The idea was that the metal must run down to the end of the runner
bar, all the inclusions in the metal and sand from the runner system
are trapped within the runner bar
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Inoculation Of Grey Cast Iron
Name the effects of inoculation of graphite flake iron?
• Reduce chill and promote graphite
• To reduce fine graphite and associate it ferrite
• To promote uniform structures
• To obtain a small increase in strength
There are two main ways of inoculation?
• Ladle inoculation
• Late inoculation
There are 3 ways of late-inoculation
• Instream inoculation
• Wire feed inoculation
• In mould inoculation
What is the nucleation of iron?
• It increase the number of points available providing site for the
growth of graphite
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Why must cast iron
have enough
inoculation?
• The possibility of white
iron forming in the fast
cooling parts of grey iron
castings is high and it will
have negative effects of
including Iron Carbide
• Iron Carbide is very hard
and brittle and machining
is extremely difficult
Very good
inoculation
Small chilled
area
Poor
inoculation
Large chill
area
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Micro Structure
In Atlantis Foundries the casting will be
97% Pearlite, 3% Ferrite & traces of Cementite
Main constituents in cast iron
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Cementite
Pearlite
Ferrite
Phosphide- eutectic
Factors that influence the properties
of the structure of grey cast iron
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Basic elements for the
composition of cast iron
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Carbon
Silicon
Phosphorus
Manganese
Sulphur
Size
Amount
Contribution of graphite flakes
Composition
Cooling
Degree of nucleation of the iron
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Characteristics Of Elements
Ferrite
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Single phase solid solution
It is very soft
Low strength
Low wear resistance
Hardness (100 Brinell to 150 Brinell)
Good machine ability
Under which circumstances will ferrite occur/forms?
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Slow rates of cooling
High silicon contents
High carbon equivalent
Pearlite
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High wear resistance
Very good tensile
Good machine ability
Cementite
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Very hard
High wear resistance
Extremely poor machine ability and brittle
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Quality/Defects
Scabbing defects can be caused by:
• High pouring temperatures
• Long pouring times
Blows
• High pouring temperatures
• Long pouring times
• Not drilling vent holes at the mould line
• Turbulence while pouring metal
• Increase resin for Coremaking
Slag
• Ladles not being slagged off properly, not using slag bond
• Pouring basin not being kept clean from slag build up
• Mould line not using correct filters to stop slag going into casting
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Slag
• Slag is formed in an electric melting furnace
• It is formed from sand, dirt or rust on the raw materials
• Slag floats on the surface of metal and must be removed
before tapping/transferring to pressure pour furnace
• Slagging off is a very unpleasant job for a Furnace Operator
• It is advisable to use less dirt, sand and rust-free charge
materials
• Many slags are liquid and difficult to collect
• It is adviceable to use SLAX-SLAGBOND
• Slax granules expands at metal temperature and it mops up
slag that is on the metal and can be lifted up with ease from
the metal
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Dangerous contaminations in
metal that can cause defects
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Lead
It can cause losing your tensile strength on casting
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Boron
It causes cracking and chill in casting
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Aluminum
May cause Pinholing defects in casting
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Nitrogen
It can cause blowholes, heavy sections in castings are mostly
affected
Titanium neutralise the effect of nitrogen
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