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Gershwin van Harte Atlantis Foundries, 16.10.2007

WCIF/AF Presentation

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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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WCIF Courses that I have done• Cores & Core Making• Moulding & Moulding Sands• Fettling & Fettling Techniques• Supervisory Management• Production & Planning• Melting & Metallurgy

Introduction

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Coremaking/Coreshop

Cured cores

Location cores

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The cores that I made was as follow:

• 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• There is two kinds of gas catalyst mainly DMEA and TEA• At Atlantis Foundries we are using DMEA

Why DMEA?

• Cure cores faster than TEA

Characteristics of Amine

• It has a fishy odour • Extremely flammable

Precautions

• Avoid skin contact• Avoid getting into eyes• High exposure causes blurred vision

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Moulding/Cold Box Process1 It is not dependent on any

heat sources for curing

2 The process is less labour intensive,therefore cheaper

3 The process can be used for both core and mould production

4 It works well with all cast metals

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

7 Designed for excellent castings with good shake-out properties in all metals

8 Produces sound castings with good surface finish, no gas defects and low metal penetration.

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9 It is permeable. If gasses doesn’t escape properly it can cause mould explosions

10It has dry strength to prevent erosion by liquid metal during pouring

11It possesses refractoriness to withstand the high temperature involved without melting and fusing of sand grains

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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 furnacesInduction furnaces: Examples ABB’s & VIP at Atlantis FoundriesAfter 250 heats it is relinedMost 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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Channel furnace/holding furnace

• There are 3 furnaces at Atlantis Foundries that holds 50 tons of Molten metal eachThis is not a Melting furnace but a storage place for liquid metal

• Precise control of temperaturesEvery second year it is relined

What is the process of metal melting?

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Factors that will cause a lining to fail

• 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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SnippersCoils

Raw materials

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Ferro Alloys

Fe S

Fe Cr

Fe Mn Fe Si

Carburiser/Carbon

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Typical Furnace charge as per work instruction at Atlantis Foundries

• Returns 2000 kg• Scrap blocks 2000 kg• Steel scrap 1000 kg• Snippers 1500 kg• Bails 1500 kg• Coils 1000 kg• Pig iron 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

• 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

Runner bar

Ingate

Runner system before cutting

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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 strengthThere are two main ways of inoculation?• Ladle inoculation• Late inoculation

There are 3 ways of late-inoculation • Instream inoculation• Wire feed inoculation• In mould inoculationWhat 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• Cementite• Pearlite• Ferrite• Phosphide- eutectic

Factors that influence the properties of the structure of grey cast iron

• Size• Amount• Contribution of graphite flakes• Composition• Cooling• Degree of nucleation of the iron

Basic elements for the composition of cast iron

• Carbon• Silicon• Phosphorus• Manganese• Sulphur

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Characteristics Of ElementsFerrite• Single phase solid solution• It is very soft• Low strength• Low wear resistance• Hardness (100 Brinell to 150 Brinell)• Good machine abilityUnder which circumstances will ferrite occur/forms?• Slow rates of cooling• High silicon contents• High carbon equivalentPearlite• High wear resistance• Very good tensile • Good machine abilityCementite• 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

• Lead It can cause losing your tensile strength on casting

• BoronIt causes cracking and chill in casting

• AluminumMay cause Pinholing defects in casting

• NitrogenIt can cause blowholes, heavy sections in castings are mostly affected

Titanium neutralise the effect of nitrogen

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