FOUNDRY SHOP 1. Introduction: Introduction: Foundry: The place where jobs are prepared by melting and pouring the molten metal into the moulds is known as foundry. Mould: A mould is cavity so prepared that can be used to make canting by pouring molten metal into it. Pattern: Pattern is a model of any component which is used to prepare moulds by placing it in sand. Casting: The molten metal poured into mould, on cooling is known as casting. Forgability: The capacity of a metal to get forged is called forgability. Types of Patterns: 1. Solid Pattern 6. 2. Split Pattern 7. 3. Multi-piece Pattern 8. 4. Match-plate Pattern 9. 5. Gated Pattern Moulding and Casting Processes: According to the method used:
1. Floor Moulding 2. Bench Moulding
Skeleton Pattern Sweep Pattern Cop and Drag Pattern Segmental Pattern
3. Pit Moulding 4. Machine Moulding
Types of Sand:
1. 2. 3. 4.
Green Sand Dry Sand Facing Sand Parting Sand
5. 6. 7. 8.
Baking Sand Core Sand Oil Sand Molasses Sand
Main Constituent of Moulding Sand
1. Silica Sand 2. Binder
3. Additives 4. Water
Qualities of Sand:
1. Good Refractoriness Refractoriness 2. Good Permeability 3. Good Flowability or Plasticity
4. Good Adhesiveness 5. Good Cohesiveness 6. Good Collapsibility
Other Requirements of moulding sand:
1. 2. 3. 4.
It should be cheap and easily available. It should be reusable to effect economy. It should not react chemically chemically with the molten metal. It should not stick to the surface of the casting.
Cores: A core can be defined as a body of sand which is used to form a cavity of desired shape and size in a casting. Cores are prepared separately in core boxes. Types of Cores:
1. Horizontal Core 3. Balanced Core 2. Vertical Core 4. Hanging Core Melting Furnaces: A melting furnace is very necessary equipment in foundry shop. It is used to melt the metal to be casted. Types of Furnaces:
1. Crucible furnaces: (a) Coke fired furnaces (b) Oil and Gas fired furnaces 2. Cupola furnace
2. Tools and Equipment used in Foundry Shop:
Foundry tools and equipment may be classified into six groups namely: 1. Hand Tools 2. Flasks 3. Mechanical Tools 4.SandTesting Equipment 5.Metal Melting Equipment 6. Fettling and Finishing Equipment I. Hand Tools: Shovel: It consist of iron pan with a wooden handle. It can be used for mixing and conditioning the sand then transferring the mixture in any container.
Trowel: These are used for finishing flat surfaces and corners inside a mould. They are made of iron with a wooden handle.
Lifter: A lifter is a finishing tool used for repairing the mould and finishing the mould sand. Lifter is also used for removing loose sand from mould.
Hand Riddle: It is used for ridding of sand to remove foreign material from it. It consists of a wooden frame fitted with a screen of standard wire mesh at the bottom.
Strike off bar: It is flat bar made of wood or iron to strike off the excess sand from the top of a box after ramming. It’s one edge is made bevelled and the surface perfectly smooth and plane.
Vent wire:It is thin steel rod or wire carrying a pointed edge at one end in a wooden handle or a bent loop at the other. After ramming and striking off the sand it is used to make small holes called vents in the sand mould to allow the exit of gases and steam during casting.
Draw Spike: It is tapered steel rod having a loop or ring at its one end and a sharp point at the other. It is used to draw pattern from the mould.
Rammers: Rammersare used for striking the sand mass in the moulding box to pack it closely around the pattern.
Slicks: They are used for repairing and finishing the mould surfaces and edges after the pattern has been withdrawn. The commonly used slicks are Heart and Leaf, Square and Heart, Spoon and Bead and Heart and Spoon.
Smoothers: They are also finishing tools used for repairing and finishing flat and round surfaces. Mallet: It is a similar wooden mallet as that used in carpentry work. In foundry work it is used for driving the draw spike into the pattern and then rapping it.
Swab:It is hemp fibre brush used for moistening the edges of sand mould which are in contact with the pattern surface, before withdrawing the pattern.
Sprue pin: It is a tapered rod of wood or iron which is embedded in the sand and later withdrawn to produce a hole, called runner through which the molten metal is poured into the mould.
Bellow:It is used to blow out the loose or unwanted sand from the surface and cavity of the mould.
Sprit level: The sprit level is used by the moulder to ensure that his bed of sand, moulding box or moulding machine table is horizontal. II. Moulding Boxes: Sand moulds are preparedin specially constructed box called flasks or moulding boxes. They are usually made in two parts, the top part is called the cope and the lower part is called the drag. These moulding boxes can be made of either wood or metal depending upon the purpose.
III. Crucibles: They are made of refractory material and are similar in shape to the ladles. They are used as metal melting pots.
Terms Related To Sand Moulds
Cope is the upper part and Drag is the lower part of the moulding box. Runner is the passage through which molten metal is poured. Gate is the small passage connecting the runner to the mould cavity. Parting Line is the line along which the sand surfaces of the Drag and Cope join each other.
Riser is the passage through which the molten metal rises up after filling the mould cavity. Pouring Basinis the enlarged portion in the form of a countersunk, at the top of the runner. Casting Defects:
1. 2. 3. 4. 5. 6.
Shrinkage Blow Holes Scar Cracks Short Casting Mould Shifting
Safety Precautions in Foundry and Casting Shop:
1. Always wear apron in the shop. 2. Don’t throw sand on each other during working. 3. Don’t waste the moulding sand. 4. Prepare sand properly before start working. 5. Select cope and drag part of proper fitting. 6. Place the pattern properly and carefully in the moulding box. 7. Draw the pattern carefully from the moulding box. 8. Never put water on molten metal, this can cause a huge explosion. 9. Never pour molten metal over wet floor. 10. Foundry shop should be properly ventilated as f umes and other chemicals may be toxic. 11. Always use glasses during casting. 12. Never use damaged or dropped crucible.
JOB No. 1 Job: To prepare a mould of single piece Solid Pattern using Green Sand. Material Required: Green Sand Tools and Equipment required: Showel, Trowel, Rammers, Sprue Pins, Draw Spike, Strike off bar, Slick, Lift, Vent wire, Hand bellow, Sprit Level, Moulding Box and given pattern. Procedure
1. 2. 3. 4. 5. 6. 7.
First of all prepare the sand properly before start working. Select cope and drag part of proper fitting. Place the drag part on moulding board. After filling the drag part with sand start ramming. Now place the pattern in the sand so that the parting line remains on the upper plane of the drag. Ram the sand properly from all sides around the pattern. Then by ramming and putting sand make surface plane around the pattern with the help of strike off bar and rammer. 8. Sprinkle a fine layer of parting sand over the drag surface. 9. Place the cope part of the moulding box over the drag portion. 10. Place two sprue pins in the vertical positions. 11. Fill the moulding box with sand. 12. Ramming is done to compact the sand. 13. After ramming excessive sand is removed with the help of strike off bar. 14. Take out the sprue pins. 15. Check the level with the help of sprit level. 16. Small holes are pierced into the level surface of t he cope with vent wire. 17. Then cope part is lifted up very carefully. 18. Then pattern is taken out with the help of draw spike. 19. Pouring basin, gates and runners are made. 20. Loose sand is taken out with lifter and hand bellow, then cope is place over the drag portion.
Precautions:
1. 2. 3. 4.
Prepare sand properly. Ramming should be done properly Pattern should be drawn carefully from the mould. Repair of moulding cavity should be done carefully.
JOB No. 1 Job: To prepare a mould of single piece Solid Pattern using Green Sand.
Diagram:
JOB No. 2 Job: To prepare a mould of Split Pattern using Green Sand. Material Required: Green Sand Tools and Equipment required: Showel, Trowel, Rammers, Sprue Pins, Draw Spike, Strike-off bar, Slick, Lift, Vent wire, Hand bellow, Sprit Level, Moulding Box and given pattern. Procedure
1. 2. 3. 4. 5.
First of all prepare the sand properly before start working. Select cope and drag part of proper fitting. Place the drag part on moulding board. After filling the drag part with sand start ramming. Now place the half portion of the pattern in the sand so that the parting line remains on the upper plane of the drag. 6. Ram the sand properly from all sides around the pattern. 7. Then by ramming and putting sand make surface plane around the pattern with the help of strike off bar and rammer. 8. Place the top part of the pattern assembled in position with the lower part. 9. Spray a fine layer of parting sand over the drag surface and pattern 10. Place the cope part of the moulding box over the drag portion. 11. Place two sprue pins in the vertical positions. 12. Fill the moulding box with sand. 13. Ramming is done to compact the sand. 14. After ramming excessive sand is removed with the help of strike off bar. 15. Take out the Sprue pins. 16. Check the level with the help of sprit level. 17. Small holes are pierced into the level surface of t he cope with vent wire. 18. Then cope part is lifted up very carefully. 19. Then pattern is taken out with the help of draw spike. 20. Pouring basin, gates and runners are made. 21. Loose sand is taken out with lifter and hand bellow, then cope is place over the drag portion.
Precautions:
1. 2. 3. 4. 5.
Prepare sand properly. Place the half part of the pattern in correct alignment with the second half part. Ramming should be done properly Pattern should be drawn carefully from the mould. Repair of moulding cavity should be done carefully.
JOB No. 2 Job: To prepare a mould of Split Pattern using Green Sand.
Diagram:
