GREEN SAND

Page 1
Technical Presentation
Green sand Molding Management
01 Oct 2011, Suranaree University of Technology,
Nakhon Ratchasima
Page 2
Prepared by U. Ittipon
INTRODUCTION
Green sand Molding process
Green sand molding is more wide develop than any other
process.
Green sand molding is replacing many of the more
expensive molding methods as sand control is being
applied.
Page 3
INTRODUCTION
Types of Molding process
-Green Sand Molding process (bentonite bonded sand)
-Chemical Sand Molding process
CO2 Mold (Sodium Silicate binder)
Shell Mold (Phenoric resin binder)
Furan Resin Mold (Furan resin binder)
Cold Box (Polyurethane resin binder)
Page 4
INTRODUCTION
Why we use Green sand Molding process
-Reasonable cost.
-Environmental friendly.
-High productivity (Economical)
-Easily adaptable to manual , semi-auto and automatic
molding Machine.
Page 5
INTRODUCTION
Green sand Molding process
Jolt Squeeze _Video file
Automatic Molding
machine _Video file
Page 6
PROPERTIES
1- Green sand for moulding must fulfil and pack tightly round the pattern under
pressure. It must be “Flowable”.
2- Green sand for moulding should be able of being deformed slightly without
cracking, so that the pattern can be withdrawn. In other words, it must exhibit
“Plastic” behaviour.
3- Green sand must have sufficient strength to strip from the patterns and support its
own weight without deforming, and withstand the pressure of molten metal when the
mould is cast. It must therefore get “Green Strength”.
4- Green sand should be “Permeable”, so gases and steam can escape from the mould
at the beginning of pouring.
5- Green sand must get “Dry Strength” to prevent erosion by liquid metal during
pouring as the mould surface dries out.
6- Green sand must guarantee a good “Refractoriness” to withstand the high
temperature involved without melting or fusing with the metal.
Page 7
SAND SYSTEM
[Increase of
Compactibility]
Bentonite New Sand
Water
Additives
Core making
Aerator
PREPARATION
MOLDING
Homogenization
Hydration
Mixing
Dust
Extraction
COOLING
New Sand
Resins
Core wash
Vertical or Horizontal
CIRCULATION
SYSTEM
POURING
Screening
Sand extracted
Magnet.
Separator
•Increase of sand
temperature
Sand adhering to castings
Sand Losses
SHAKEOUT
(Drum or Vibratory)
•Burnout of Clay
and Sea Coal
•Gas emissions
Page 8
CASTING DEFECTS
Castings defects relative to Green Sand Moulding could be due to :
- The COMPONENTS of the Green Sand for Moulding
- The PROPERTIES of the Green Sand for Moulding
- The UTILIZATION of the Green Sand for Moulding
Page 9
GREEN SAND COMPONENTS
Foundry sand
Bentonite
Additives
Water
Dead Clay
Page 10
FOUNDRY SAND
Available Materials
SILICA
CHROMITE
ZIRCON
OLIVINE
Formula
SiO2
FeO Cr O3
Zr Si O4
2 (MgFe) O
SiO2
Specific Density
2.65
4.3
4.7
3.5
Bulk density
1.6
2.7
2.8
1.95
Sinterpoint
1730
2095
>2200
1857
Thermal
conductivity
Low
High
High
Low
Reaction
mold/metal
High
Low
Low
Low
Utilisation
All metals
Steel &
Manganese
Steel
Steel
Disponibility
High
Very low
Very Low
Good
Price
Low
High
High
Medium
Page 11
SILICA SAND
Material used for its « Economic » advantages and
sufficient thermal resistance
Important characteristics:
The Grain size
The Grains distribution
The Grain surface shape
The thermal resistance
(sinter Point)
Silica content
Page 12
SILICA SAND
Al2O3 = Max 0.13 %
Fe2O3 = Max 0.06 %
Physical properties:
Density = 1.5
Hardness = 7
pH = 7
LOI = Max 0.15%
50
Grain size Distribution
45
Individual residue in %
Main components:
SiO2 = Min 98 %
40
35
30
25
20
15
10
5
0
600
425
300
212
150
106
75
53
Pan
Sieves opening in M icrons
Moisture = Max 0.1%
•AFS No = 55 - 60
Sinter point = Min.1500 Co
•3 Screens Distribution with 80 % min on
cumulative ASTM sieves 50, 70, 100
Page 13
SILICA SAND
70 AFS
100
90
80
70
60
50
40
30
20
10
0
72 AFS
100
90
80
Residue %
70
60
50
40
30
20
10
27
0
14
0
70
40
20
27
0
70
14
0
70 AFS
40
35
30
25
20
15
10
µm
0
<5
3
27
0
20
0
14
0
10
70
50
40
30
20
12
5
0
6
Residue %
40
20
6
0
6
Residue %
AFS GRAIN FINENESS
Page 14
SILICA SAND
Thermal expansion
Temperature
Crystallography
of SiO2
Density
Expansion
rate
Ambient
α Quarz
2,65
= F (oC)
573 oC
Β Quartz
2,49
1,5%
867 oC
Tridymite
1470 oC
Cristobalite
2,33
3~5%
1730 oC
Amorphous Silica
Page 15
SILICA SAND
Thermal expansion
2
SILICA
1
OLIVINE
CHROMITE
14
00
12
00
10
00
80
0
60
0
40
0
20
0
0
0
% Expansion
ZIRCON
Bentonite
-1
Degrees Celsius
Page 16
GREEN SAND COMPONENTS
Foundry sand
Bentonite
Additives
Water
Dead Clay
Page 17
RULE OF BENTONITE = THE SAND BINDER
Sand Grains
x 3800
Bentonite
Sand Grains
(bridge between sand grains)
Page 18
WHAT IS BENTONITE?
• Bentonite is a type of clay whose main constituent is Montmorillonite
belonging to the smectite group.
CLAYS
(app. 200 types)
1/1 GROUP
Primary layers 7 Å
2/1-1 GROUP
Primary layers 14 Å
2/1 GROUP
Primary layers 10 Å
[Tetrahedral - Octahedral – Tetrahedral] Layers
Sub-groups and families
Sub-groups and families
Sub-groups and families
Other Clays family
Other Clays family
Other Clays family
Other Clays family
Other Clays family
SMECTITE FAMILY
Clays Classification
•Division : particles size less than 2 microns
• Appearance : no symmetrical particles with lamella tendency.
Sub-groups and families
MONTMORILLONITE:
[Hydrated Alumina and Magnesia silicates]
• Dispersion : possibility to make colloidal suspension with more or
less stability in water
• Chemical formula : alumina silicates
[Rk: 1 micron = 10,000 Angstrom units (Å)]
Page 19
WHAT IS BENTONITE?
Montmorillonite has been identified in France by Mr. Damour and Mr. Salvetat
in 1847 on a small mine nearby Montmorillon city (France).
Natural Treasure
The first industrial exploitation at the beginning of the 20th Century started at a
mine located near Fort Benton in Wyoming province (USA). This explains the
origin of the term “Bentonite” which was first a trade name.
Page 20
WHAT IS BENTONITE?
Bentonite is a relatively soft stone,
formed over geological time by the
natural alteration of volcanic tuffs
due to acid or alkaline rain.
Page 21
LATTICE STRUCTURE
Silicon-Oxygen tetrahedral layer
App.
10 Å
Aluminium dioctahedral layer
Silicon-Oxygen tetrahedral layer
Na+
Na+
Ca++
Na+
Na+
Na+
Silicon-Oxygen tetrahedral layer
Aluminium dioctahedral layer
Silicon-Oxygen tetrahedral layer
Page 22
BENTONITE MINES
In the nature, existing exchangeable cations are:
calcium => Natural Calcium Bentonite
sodium => Natural Sodium Bentonite
Most exploitable mines in the world are Natural Calcium Bentonite
Therefore, we are proceeding to a chemical treatment to substitute the Ca
cation by Na cation .
This operation is called “ACTIVATION PROCESS” that consist in
mixing bentonite with soda ash, combining specific moisture, mechanical
treatment and temperature conditions.
After activation, processed bentonites are called:
“Activated Sodium Bentonites”.
By pass
process
By pass
process and
characteristics
Page 23
BENTONITE : LAYERS STRUCTURE
The space between the layers is maximum with Na-Ions
Page 24
BENTONITE - MILLING
[ Material Flow – Milling ]
Cyclone
system
Granules
Box Feeder
Raymond
Mill
Quality
Control
Finish Product
Quality
Control
Page 25
BENTONITE : FROM MINING TO FOUNDRY
Mining
Exploitation
Stocking
Packing
Activation
Drying
Milling
(PM 12)
Page 26
BENTONITE : FROM MINING TO FOUNDRY
Mining Exploration
Mining Exploitation
Raw Material
Raw Material Stocking
Activation / Extrusion
Granules
Drying
Quality
control
Granules Stocking
Milling / Drying
Finish Product
Finish Products Stock
Packing
Delivery to Foundry Industry
Foundry
Page 27
BENTONITE : LABORATORY CONTROL
Swelling Volume
Methylen Blue Retention
Water content
Particle size
VDG P 69 Norm Method
Wet Tensile Strengths & Green Compression Strengths
Page 28
BENTONITE : MAIN CHARACTERISTICS
-Swelling: one of the main characteristics of Montmorrillonite is to fix water molecules between the
layers which causes the inner structural water. Swelling highly depends on the nature and quantity of the
exchanged cations but also on the % of Na2CO3 for Activated Sodium Bentonites.
swelling volume ml / g
20
18
15
17
15
10
10
5
5
0
0
2
4
6
8
activation rate : % soda ash
Page 29
BENTONITE : MAIN CHARACTERISTICS
-Swelling:
% Na2CO3 activation changes according to the origin and content of Montmorrillonite
Page 30
BENTONITE : MAIN CHARACTERISTICS
Control of the Activation = Wet Tensile Strength
Page 31
BENTONITE : MAIN CHARACTERISTICS
- Montmorillonite content:
The montmorillonite content is improperly associated to the measurement of the Methylene Blue
Retention. Other methods are difference of density or X-ray diffraction. A calibration is possible to make a
link between the % of Montmorillonite and the MB retention. Professionals agreed to call bentonite, all
clays with Montmorillonite content over 60%.
- Methylene Blue Retention = method based on the retention capacity of Montmorillonite by
the molecules of dyestuff the Methylene Blue. In fact, this test indicates the specific surface of bentonite.
Page 32
BENTONITE : MAIN CHARACTERISTICS
- Water content:
2 types of water must be considered in case of Montmorillonite:
- Bonding water (existing in the lattice network structure)
[ evaporation from 100 OC ] = important factors because:
- Exceeding, it can lead to plugging in the pneumatic transport system
- Too low means bentonite will be difficult to re-hydrate
- Constitution water in the macroscopic primary layers network
[ influence on the durability of bentonite - evaporation around 500 OC ]
Page 33
BENTONITE : MAIN CHARACTERISTICS
- Particle Size: measure of the sieve residue at 75µm with specific equipment.
- Too coarse particles can affect the speed of the water absorption.
- Too fine particles can affect the consumption of bentonite (lost in dust collectors)
Page 34
BENTONITE : MAIN CHARACTERISTICS
- Carbonates content:
The purpose is to determine the Total carbonates. (all carbonates existing in the bentonite ie. Na, Ca, Mg,
etc…). This process is not to control the activation level but the consistency of the bentonite.
[The volume of CO2 given off when attacked by hydrochloric acid. Results are expressed in CaCO3].
- Cohesion characteristics:
The purpose is to measure the binding capacity of bentonites. These characteristics will be measured by
introducing another component - Silica sand.
Rk = Control receipt on bentonite = VDG P 69 – Din Method as mixture of 100 parts silica sand (AFS 5560) with 5 parts bentonite and necessary water to get 45% Compactibility.
- Test of Compressive Strengths, Shear Strengths, Wet Tensile strengths.
Page 35
BENTONITE : MAIN CHARACTERISTICS
- Durability:
Capacity of the bentonite to loose its water more or less quickly.
3 methods can be applied:
1- Testing the cohesion characteristics on bentonite heated at 550OC (1/2 H in ventilated
furnace) based on the VDP 69 – Din Method. Durability is the % of drop between the characteristics
before and after heating.
2- Comparing the MBR on bentonite heated at different temperatures.
450
400
MBR mg/g
350
300
250
200
bentonite 1
150
bentonite 2
100
50
0
0
100
200
300
400
500
600
700
800
temperature °C
Page 36
GREEN SAND COMPONENTS
Foundry sand
Bentonite
Additives
Water
Dead Clay
Page 37
LUSTROUS CARBON FORMER
When molten metal is poured, the moulding sand undergoes some
modification that influence casting quality:
Liquid metal could penetrate in the green sand interstice
(Metal penetration defects)
The mould atmosphere is wet and could oxidize the metal.
Oxides could create defects but also react with silica and increase
the casting surface alteration.
Solution :
Addition of Lustrous
Carbon Former
Page 38
LUSTROUS CARBON FORMER
Basic data for Coals and resins (asphalt) suitable for the production of lustrous carbon:
Feature
LOI, %
Sulphur content, %
Nitrogen content, %
Volatiles, %
Swelling Index
(according to DIN 51741)
Lustrous Carbon, %
Surface quality
Coals
Resins
92 to 96
0,4 to 0,8
1,2 to 2,6
34 to 40
2 to 7
98 to 100
0,1 to 0,3
0,1 to 3,0
76 to 98
0
9 to 14
Moderate to very good
36 to 44
Only in combination with
sea coal, good to
excellent, especially with
thin wall castings.
Page 39
ECOSIL
Lustrous carbon former, (sea coal)
is added to green sand in order to :
• prevent metal penetration.
• obtain a smooth casting surface.
• lessen the incidence of expansion
defects (silica sand dilution).
• reduce the mould-wall movement
and formation of shrinkage
cavities.
• create excellent breakdown
characteristics of the mould upon
shakeout.
• reinforce and to stabilise the
green strength properties of
moulding sand.
Page 40
ADDITIVES
Organic Carbohydrates - Starch
To improve moulding sand properties as:
- Elasticity (sand deformation)
- Erosion and abrasion resistance
In specific cases, could compensate the expansion of silica grains (in
fact to reduce expansion defects as scab, rat tail, veining, etc…)
Page 41
GREEN SAND COMPONENTS
Foundry sand
Bentonite
Additives
Water
Dead Clay
Page 42
WATER
One of the most influent element.
Development of the Moulding Sand Properties
Contains impurities that affect the bentonite properties
Page 43
WATER : INFLUENCE OF SALTS
Normal
Na+
Na+
Salt de-actives the
bentonite electrostatic
bonding properties
Polluted
Na+
Na+
Cl-
Page 44
COMPOSITION : INFLUENCE OF WATER
De-activation phenomenon could be verified by the WTS test.
Page 45
COMPOSITION
Foundry sand
Bentonite
Additives
Water
Dead Clay
Page 46
DEAD CLAY
Oolitisation process
The part of bentonite heated above 500OC loses its structural water and settles itself on
the sand grain.
This bentonite loses permanently its properties and becomes a “dead clay”.
At each sand circulation, a part of the sand grains is coated by this dead clay. This is
the “Oolitisation process” .
Dead clay reduces the expansion of the green sand and permits to fix a part of the free
water in the mold.
Dead Clay
High Oolitisation
Low Oolitisation
Page 47
COMPOSITION
GREEN SAND MOULDING FORMULA
100 % = (Silica sand+Dead Clay) + (Active Clay+Combustibles) + Water
Refractory
Absorbents
Catalyst
100 % = SiO2 + DC + AC + LOI+ H2O
The Green Sand Formula depends mainly on:
- the type of sand plant (mixer, cooling system, etc..)
- the type of moulding process
- the type of shake-out process
- the materials used (new sand, bentonite, additives, etc…)
- the castings produced (sand/metal ratio, type of metal, etc..)
Page 48
COMPOSITION
GREEN SAND MOULDING COMPOSITION
100 % = (Silica sand+Dead Clay) + (Active Clay+Combustibles) + Water
Generally, the moulding sand is made up with :
[Iron Castings]
[Steel Castings]
SiO2= 75% to 85%
SiO2= 75% to 85%
DC= 5% to 8%
DC= 6% to 9%
AC= 6% to 10%
AC= 8% to 12%
LOI= 3% to 5%
LOI= 2% to 3%
H2O= 2% to 4%
H2O= 2% to 4%
Page 49
CONTROL THE COMPOSITION
1- Active Clay (using Methylene-blue method)
•
The AC determines the quantity (in %) of bentonite that is able to bond the sand
grains. The AC represents the bentonite that could absorb a methylene-blue
solution.
•
The AC content mainly depends on:
•
The type and origin of bentonite (MB retention of the bentonite in use in the
sand system) – up-date its value regularly and calibrate each new MB solution
before dosage
•
The durability of the bentonite (thermal resistance)
•
The type of metal pouring (grey iron, ductile iron, steel, etc..)
•
The Foundry equipments (molding process, mixing process, cooling process,
shake-out process)
Page 50
CONTROL THE COMPOSITION
2- Loss on Ignition (LOI)
•
The LOI determines any element burnt at 900oC that is the combustible materials
in the green sand system. In fact, LOI relates to the carbon former (seacoal), the
structural water of bentonite, the carbonless of core sand, etc….
•
LOI permits to estimate the exchange of sea coal in the sand system.
The LOI content mainly depends on:
•
The type and origin of sea coal (composition of the original sea coal added in
the sand system),
•
The quantity and type of core sand
•
The type of metal pouring (grey iron, ductile iron, steel, etc..)
•
The Foundry equipments (shake-out process and dust collectors)
Page 51
CONTROL THE COMPOSITION
3 – Water content
•
The Water Content is one of the most important and easiest test. Water content
affects every properties of green sand, but mainly permits to swell the bentonite.
The test represents the water loss at 105oC.
•
Control sometimes its pH, conductivity (<500 µS/cm²), hardness and composition if
necessary
•
The Water content depends on:
•
The type, origin and quantity of bentonite, sea coal and foundry sand in the
system.
•
The type of metal pouring (grey iron, ductile iron, steel, etc..)
•
The Foundry equipments and its influence on the compactibility required
(molding process, mixing process)
•
The cooling process (water content in the returned sand system)
Page 52
CONTROL THE COMPOSITION
4 – Silica and Dead clay content
•
The silica and dead clay represent the refractory part of the green sand.
•
Dead clay is the bentonite that has lost its structural water.
The Silica content mainly depends on:
•
The type, origin and quantity of foundry sand and core sand in the system. (Vs
the sintering point of original foundry sand)
The Dead clay content mainly depends on:
•
The type, origin and durability of the original bentonite added in the sand
system,
•
The type of metal pouring (grey iron, ductile iron, steel, etc..)
•
The quantity of silica sand added in the system.
Page 53
CONTROL THE COMPOSITION
Inactive fines
•
Dead- burnt bentonite ( Bentonite which has lost the structural water)
•
Coal dust particles less than 0.02 mm.
•
Dead –burnt coal dust ( coke, ash).
•
Natural fines from the base sand.
•
Crushed and thermally disrupted silica sand grains.
Total fines ( Total clay)
Fines are defined as all the particles size that are smaller than 0.02 mm.
•
Active fines (active bentonite)
•
Inactive fines
Page 54
CONTROL THE COMPOSITION
100 % = (Silica sand+Dead Clay) + (Active Clay+Combustibles) + Water
Example:
100
Water
75
LOI
50
Active Clay
25
Dead Clay
Silica
0
1
2
No 1 :High silica content (85%), therefore low bentonite , sea coal and dead clay contents.
Main problems are : all defects in relation with the expansion of the silica as veins, scabs but also explosion
- metal penetration, erosion, abrasion defects.
No 2 : Lower silica content (70%) no problem in relation with the expansion of the silica.
Main problems are: all defects as broken mould, formation of lumps, sand-slag defects,…
Page 55
Page 56
PROPERTIES
“First” Control
•
•
•
•
Compactibility = Plastic or not?
Water content = Dry or wet sand?
Temperature = Hot or cold?
Strengths = Brittle or not?
Page 57
PROPERTIES : COMPACTIBILITY
The compactibility indicates the water tempering degree of the green sand moulding.
Represented by a percentage number, the compactibility test determines the
decrease in height of a loose mass of sand under the influence of a controlled
compaction.
The compactibility is directly related to the sand quality or the performance of a molding
sand mixture.
The following factors affect the compactibility :
The water content (sand temperature of returned sand)
The mixing time (calibration and mulling energy)
The Active clay and LOI levels
The inert fines (fines from silica absorbing water)
The quality of Bentonite (Swelling capacity, water holding capacity)
The quality of sea coal (type of coal and coke transformation capacity )
The used of starch and Cereals (change the bonding properties)
Video. file
Page 58
COMPACTIBILITY
Compactibility %
46
Dry sand
50 mm±1
Wet sand
44
OK
42
40
38
36
34
Sand Specimen
Compactibility
32
Water Content %
Page 59
PROPERTIES : COMPACTIBILITY
Compactibility %
46
Active clay (MBR) %
44
42
40
7%
8%
9%
38
36
34
32
Water content %
Page 60
PROPERTIES : STRENGTH
The mould sand strength can be expressed by several standard tests :
Green Compression Strength :
Wet Tensile Strength
Dry Compression Strength
But also : green shear strength, resistance to fissuring, resistance to abrasion,
etc…
They depend on the composition and the preparation of the moulding sand
Page 61
PROPERTIES
Green compressive strength - GCS: (N/cm2)
The working strength of molding sand is a combination of
compressive strength and deformation or mold plasticity ( Keep mold
wall stability).
The most influential factor in controlling GCS is the tempering
moisture , general composition, type and amount of Bentonite binder
and degree of mulling ( Active clay and moisture ratio)
Green tensile strength: mostly effect to mold wall stability of
horizontal molding on cope side.
Green Shear strength: mostly effect during remove the pattern or put
core in Mold.
Test Simpson _Video file
Test Rid _Video file
Test Shear _Video file
Page 62
PROPERTIES
Wet Tensile Strength – WTS : N/cm2
The working strength for the sand resistance to scabbing and other
sand expansion defect that occur on the iron – sand face after pouring.
The water (moisture) from sand layer moves away from casting
surface and creating a water condensation zone between the dry and
wet sand area.
The strength of the sand in layer of condensation zone is called “ Wet
tensile Strength”
The most influential factor in controlling WTS is type and amount of
bentonite including the content of inactive fines and permeability
Test _Video file
Page 63
Strengths:
Problem zones of bentonite bonded sand”
Heat penetration into
Foundry Mold
Form – Compacted moulding sand
Condensation zone
Form - Dried and Burnt moulding sand
Liquid Iron
Molten
Metal
Dry tensile strengths
Condensation
zone
“WTS Area”
Form-- Dried sand
Form
Form – Tempered Molding
sand
Green strengths
- - - - Effect of Starch
Strengths N/cm2
Strengths profile during the heat penetration into moulds
Molten
Metal
Condensation
zone
Form-- Dried sand
Form
Distance to the liquid metal (mm)
Form – Tempered Molding
sand
Permeability
Permeability through different zones of moulding during pouring process
Page 64
PROPERTIES : PERMEABILITY
The permeability indicates the ability of the gas to escape through the mould
The permeability is directly related to the sand composition
The following factors affect the permeability :
The water content
The silica sand AFS index and its repartition
The Active clay, dead clay and LOI levels
The inert fines (fines from silica absorbing water)
The used of starch and Cereals
The moulding machine
The shake-out
Page 65
Green Sand Molding test report
Page 66
Green Sand Molding test report
Page 67
Materials Consumption Vs Cast Iron Quality
Heat penetration into mold
Iron – Sand ratio
New sand Consumption
Bentonite Consumption
Coal Dust Consumption
Page 68
Metal Cast into the mould
“Heat Penetration”
__________
Transformations of the molding sand materials
Page 69
FOUNDRY
MOULD
Page 70
Pouring
Page 71
Evaporation of the water
at the mould surface
(to external forms of the mould)
Page 72
Condensation of
the water:
“Formation of wet layers”
Page 73
Heat Radiation from liquid metal
Page 74
Reducing Atmosphere
Page 75
Lustrous Carbon Film
Formation of a
Lustrous carbon film
Gas Cushion
Page 76
CASTING
FOUNDRYC
ASTING
SAND BURNT
Wet layers
Page 77
Influences : Iron – Sand Ratio
Foundry Example
Iron-Sand ratio = 1:10
Sand Replenishment = 90 kg/t Fe
Bentonite consumption = 45 kg/t Fe
Coal dust consumption = 18 kg/t Fe
Page 78
Influences
Foundry Example
Iron-Sand ratio = 1:10
Sand Replenishment = 90 kg/t Fe
Bentonite consumption = 45 kg/t Fe
Coal dust consumption = 18 kg/t Fe
Page 79
Influences
Foundry Example
Iron-Sand ratio = 1:10
Sand Replenishment = 90 kg/t Fe
Bentonite consumption = 45 kg/t Fe
Coal dust consumption = 18 kg/t Fe
Page 80
Influences
Foundry Example
Iron-Sand ratio = 1:10
Sand Replenishment = 90 kg/t Fe
Bentonite consumption = 45 kg/t Fe
Coal dust consumption = 18 kg/t Fe
Page 81
Bentonite-bonded molding sand Balance
Why a “Balance” is necessary:
• to maintain a constant composition of the green sand molding
• to stabilize the properties of the green sand molding
• to control the right utilization of the green sand molding
• to simulate a specific future condition or future phase of
development
Circulation system – General principle
[TOTAL AMOUNT = 100]
A0
0,1 A0
10% Removed
A
B
[TOTAL AMOUNT = 100]
90 A
10 B
90 A
B
HOMOGENISATION
A0
0,1 A0
90 A
10 B
B
[TOTAL AMOUNT = 100]
81 A
19 B
81 A
9B
B
10% Removed
10% Addition
Circulation 2
HOMOGENISATION
A0
0,1 A0
81 A
19 B
B
[TOTAL AMOUNT = 100]
10% Addition
Circulation 1
72,9 A
17,1 B
B
10% Removed
10% Addition
Circulation 3
HOMOGENISATION
Page 83
Circulation system – General principle
From this relation, it can be determined how “high” the percentage of a newly added material is,
at a specific time.
Page 84
Application to the sand circulation system
Bentonite New Sand
Water
Core making
New Sand
Resins
Core wash
Sea Coal
PREPARATION
MOLDING
Homogenization
Hydration
Mixing
Dust
Extraction
COOLING
Vertical or Horizontal
1.
Time needed per sand circulation
2.
Number of circulations per working
time (hour/day/shift).
3.
CIRCULATION
SYSTEM
Exchange rate of materials per
POURING
circulation at a specific time
Screening
Sand extracted
Magnet.
Separator
Sand adhering to castings
Sand Losses
SHAKEOUT
• Burnout of Clay
and Sea Coal
• Increase of sand
temperature
• Gas emissions
(Drum or Vibratory)
Page 85
Application to the sand circulation system
When considering the total moulding sand system,
- A0 is the total amount of sand in the system as [sum of the sand in the machine bunkers, in the used
sand silos, on the cooling conveyor, etc…].
- BZ is the sum of all additives as [new sand +recovered core sand + bentonite + sea coal]
- Bn is the percentage of all new additives in the total sand system after “n” circulations.
⇒Bn is the part of the total sand that has been exchanged by the total new additives after “n”
circulations.
Circulation: During a circulation “x” parts of Material (B) is added to an amount of Material (A) and
the same quantity (x parts) is drawn out of the system. After this both materials are homogenised.
Addition: Material (B) is added, “x” is the quantity added as a percentage of the amount of material
(A).
Exchange: After “n” circulations there remains 100% material (B). Material (A) is completely
exchanged.
Page 86
Application to the sand circulation system
Page 87
UTILIZATION : green sand circulation report
40
F OUN D R Y XXX - A ddit ives
co nsumpt io n in k g/ T o f liquid met a l
35
30
25
20
15
10
5
0
J
a
n
F
e
b
M A
a p
r- r-
M
a
y
J
u
n
J
ul
-
S
e
p
O N
ct o
- v
D
e
c
J
a
n
F
e
b
M A M
a p a
r- r- y
J
u
n
New sand 2
2. 0. 0. 7. 20 35 42 48 24 16 15 11 20 15 4. 1. 5.
New sand 1
65 96 50 26 24 21 15 21 26 15 20 26 22 13 37 48 63
Core sand
62 61 62 53 58 61 53 63 78 60 68 81 52 67 71 62 57
Seac oal
5. 5. 7. 7. 8. 10 7. 7. 6. 9. 5. 6. 6. 5. 5. 5. 6.
bentonite
33 32 25 28 29 25 29 28 27 30 24 29 30 26 30 32 30
180
160
140
120
100
80
60
40
20
0
s
a
n
d
sc
o
n
s
u
m
p
tio
n
s
e
a
c
o
a
la
n
db
e
n
to
n
itec
o
n
s
u
m
p
tio
n
The green sand circulation system report : essential
driver for technicians
Follow the consumption
of your additives in kg/T
of liquid metal
Be aware of :
-Sand system circulation speed
-Regeneration of additives
-Changes of additives formula
Page 88
UTILIZATION : Data collection (example)
Consumption
Date
Total mix
Sand
Bentonite
Sea coal
- kg -
ADDITIVE RATIO ON JANUARY-FEBRUARY 2007
Consumption ratio ~ kg per Mt Melting ~
Core Sand
Melting
- Mt -
Sand
Bentonite
Sea Coal
Actual
Core Sand
Recovery
Total Sand
Total Bentonite Total Seacoal
08/01/2007
590
5900
6490
1180
13367
140.6
41.97
46.17
8.39
76.1
118.05
46.17
8.39
09/01/2007
587
5870
6457
1174
14631
154.0
38.12
41.94
7.62
76.0
114.14
41.94
7.62
10/01/2007
519
5190
5709
1038
13529
122.4
42.39
46.63
8.48
88.4
130.80
46.63
8.48
11/01/2007
522
5220
5742
1044
9901
118.2
44.18
48.60
8.84
67.0
111.22
48.60
8.84
12/01/2007
579
5790
6369
1158
10890
136.5
42.41
46.65
8.48
63.8
106.23
46.65
8.48
15/01/2007
673
6730
7403
1346
12034
147.7
45.56
50.12
9.11
65.2
110.74
50.12
9.11
16/01/2007
529
5290
5819
1058
8978
127.4
41.53
45.69
8.31
56.4
97.93
45.69
8.31
17/01/2007
599
5990
6589
1198
15304
160.7
37.27
41.00
7.45
76.2
113.45
41.00
7.45
18/01/2007
577
5770
6347
1154
12820
141.4
40.80
44.88
8.16
72.5
113.31
44.88
8.16
19/01/2007
646
6460
7106
1292
12169
144.5
44.72
49.19
8.94
67.4
112.10
49.19
8.94
22/01/2007
635
6350
6985
1270
11017
145.2
43.74
48.11
8.75
60.7
104.44
48.11
8.75
23/01/2007
632
6320
6952
1264
11581
153.1
41.29
45.42
8.26
60.5
101.83
45.42
8.26
24/01/2007
646
6460
7106
1292
10765
151.0
42.77
47.05
8.55
57.0
99.80
47.05
8.55
25/01/2007
621
6210
6831
1242
10633
151.1
41.09
45.19
8.22
56.3
97.36
45.19
8.22
26/01/2007
597
5970
6567
1194
10066
148.7
40.14
44.15
8.03
54.1
94.28
44.15
8.03
28/01/2007
250
2500
2750
500
6411
58.6
42.64
46.90
8.53
87.5
130.11
46.90
8.53
29/01/2007
523
5230
5753
1046
8348
126.2
41.46
45.60
8.29
52.9
94.40
45.60
8.29
30/01/2007
533
570
5330
5700
5863
6270
1066
1140
8566
11241
120.2
151.8
44.34
37.56
48.77
41.31
8.87
7.51
57.0
59.3
101.34
96.81
48.77
41.31
8.87
7.51
31/01/2007
TOTAL
AVG
SD
10828
108280
119108
21656
212250
2599
570
5699
6269
1140
11171
136.8
41.79
45.97
8.36
66.02
107.81
45.97
8.36
90.61
906.10
996.71
181.22
2232.13
22.77
2.33
2.56
0.47
10.76
10.85
2.56
0.47
Page 89
31
/01
/2
30
/01
/2
29
/01
/2
28
/01
/2
27
/01
/2
00
7
00
7
00
7
00
7
00
7
00
7
31
/01
/2
30
/01
/2
29
/01
/2
28
/01
/2
27
/01
/2
26
/01
/2
00
7
00
7
00
7
00
7
00
7
00
7
00
7
00
7
00
7
00
7
00
7
00
7
00
7
00
7
00
7
00
7
00
7
29
/01
/20
07
30
/01
/20
07
31
/01
/20
07
27
/01
/20
07
28
/01
/20
07
25
/01
/20
07
26
/01
/20
07
23
/01
/20
07
24
/01
/20
07
22
/01
/20
07
20
/01
/20
07
21
/01
/20
07
18
/01
/20
07
19
/01
/20
07
17
/01
/20
07
15
/01
/20
07
16
/01
/20
07
13
/01
/20
07
14
/01
/20
07
11
/01
/20
07
12
/01
/20
07
08
/01
/20
07
09
/01
/20
07
10
/01
/20
07
Foundry sand
26
/01
/2
00
7
25
/01
/2
24
/01
/2
23
/01
/2
22
/01
/2
21
/01
/2
20
/01
/2
19
/01
/2
18
/01
/2
17
/01
/2
16
/01
/2
15
/01
/2
00
7
00
7
00
7
00
7
00
7
00
7
00
7
Bentonite
25
/01
/2
00
7
00
7
00
7
00
7
00
7
00
7
00
7
00
7
00
7
Sea coal
24
/01
/2
23
/01
/2
22
/01
/2
21
/01
/2
20
/01
/2
19
/01
/2
18
/01
/2
17
/01
/2
16
/01
/2
00
7
kg / Mt of liquid Metal pouring
15
/01
/2
14
/01
/2
13
/01
/2
12
/01
/2
11
/01
/2
10
/01
/2
09
/01
/2
08
/01
/2
kg / Mt of liquid Metal pouring
00
7
00
7
00
7
00
7
00
7
00
7
00
7
kg / Mt of liquid Metal pouring
14
/01
/2
13
/01
/2
12
/01
/2
11
/01
/2
10
/01
/2
09
/01
/2
08
/01
/2
UTILIZATION : Consumption report (example)
FOLLOW-UP OF THE CONSUMPTION'S RATIO
SPEC = 150-250 kg
250.00
225.00
200.00
175.00
150.00
125.00
100.00
75.00
50.00
SPEC = 40-60 kg
70.00
60.00
50.00
40.00
30.00
20.00
SPEC = 15-20 kg
25.00
20.00
15.00
10.00
5.00
Page 90
UTILIZATION : GSB calculation(example)
Page 91
Thank you
Page 92