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Casting manufacturing process guru Gobind Singh indraprastha university
- 1. Casting • Manufacturing Process– liquid metal is going to solidify in given shape and size to get the desired product.
- 2. Casting Term ology •Mould / Mold – A void created in compact sand / metal / wax mass • Filled with molten metal to produce the casting. • Moulding / Molding – the process of producing the mould.
- 3. Pattern • Replica /model of desired casting • Packed in moulding material to produce the a cavity.
- 5. Flask • Hold thesand the intact. • Material – upper moulding flask • Cope – upper moulding flask • Drag- lower • Runner – is the passage trough which molten metal reach up to cavity. • Parting Line – drag cope surface meet each other. • Riser – Reservoir of molten metal – to compensate the reduction in volume of liquid metal due to contraction.
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- 8. Pattern Allowance • Thedifference in dimension of pattern to final dimension of casting. • Reason • 1. Shrinkage or contraction allowance– cooling from pouring temp to room temp.
- 9. • Liquid Contractionof riser – compensated by riser • Solidifying Contraction - compensated by riser • Solid Contraction --- compensated by pattern • Influencing Factor - pouring temp • Design and dimension of casting • Type of metal
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- 11. Draft allowance • Purpose– to facilitate easy withdrawal of pattern from the mould without damaging the surface and edge.
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- 15. Rapping or shakeallowance • R
- 16. Pattern Material • Numberof casting • Dimensional accuracy required • Surface Finishing • Casting method
- 17. Pattern Material • Wood– cheap and abundance • Shaped in different shape • Light in weight • Good surface finishing • Wear out quickly • Susceptible to moisture
- 19. Metals • Casting –large in number • Closer dimensional accuracy • Longer life • Costlier • Machining required • Heavy in weight • Rusted • Ex- cast iron, brass, Al etc.
- 20. plastics • Lightness inweight • High strength • Resistance to wear • Fine surface finish • Resistance to corrosion • Reasonable cost
- 21. plaster • Plaster ofparis or gypsum cement • Easily shaped • Carries high compression strength • Closer dimensional accuracy.
- 22. wax • Used ininvestment casting • For complicated shape
- 24. Master pattern • Usedfor preparing the moulds for metal castings which are later used as metal pattern for further moulding work. • Carry double shrinkage allowance.
- 25. Type of pattern •Solid and single piece pattern • Simplest in all type , made in one piece and carries no joint , partition or loose pieces. • Cheapest
- 27. Two piece orsplit pattern • Difficulty in mould making and withdrawn of pattern • Made in two parts joint at the parting line • Can be multiple piece
- 31. Match plate pattern •Objective – rapid production of small and accurate casting on large scale. • Greater dimensional accuracy • Construction cost is high but compensated by high production. • Pattern made in two parts. • One piece is mounted one side and other on the side of plate called match plate.
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- 34. Gated Pattern Objective –mass production of small casting Multi cavity moulds are prepared Patterns are connected to each other by gate former which provide suitable channels.
- 35. Sweep pattern • Usedfor preparing mould of large symmetrical casting. • Large saving in time, labour and material. • Consists – base, spindle, wooden template • Sweep rotated about the spindle to form the cavity.
- 38. Pattern with loosepiece • Have loose piece in order to enables their easy withdrawal from the mold.
- 39. Segmental pattern • Usedfor large circular casting • Avoiding the use of solid pattern of exact size. • Segment is moved from one position to second in mold .
- 40. Skeleton pattern- castingsize very large and heavy, hollow pattern
- 41. Only out sidefeatures
- 43. Cope and dragpattern- riser, runner and ingate are integral part of pattern
- 44. Properties required inthe Foundry sand • Refractoriness – with stand high temp. of molten temp. without fusing. • Depend upon – silicon oxide quantity in sand (melting temp. 1710 C) • Shape and size of sand grain • Presence of iron oxide, calcium, potassium and sodium.
- 46. Permeability • Allows thegases and steam to escape • Reason – casting unsound or blast • Depend upon – grain size and shape, proportion of water and clay, ramming of sand. • Increase by venting
- 50. Adhesiveness and Cohesiveness •Ad. – capability of adhering to the surface of other material • Objective- adhering to the moulding flask. • Coh.- rammed grain particle bind together • Depends upon- grain size, clay, and moisture content.
- 52. collapsibility • Sand mouldautomatically collapses after solidification of casting. • Reason – tear and cracking in casting.
- 53. Sand term ology-Green sand • Freshly prepared mould sand in which there is enough moisture to give it sufficient bond. • Composition – 70-85% silica, 10- 20% clay, 3-6% water, 1-6% additives
- 57. Effect of rammingon the moulding sand • Increase the density of mould • Increase the mould hardness and strength. • Decrease the permeability.
- 58. Other sand termology • O
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- 60. Solidification of liquidmetal • Skim forming • Dendritic growth
- 61. Chills • To provideunidirectional solidification in casting.
- 62. Gating system variable –Temp. Gradient, unidirectional solidification, erosion of sand, absorption of air * Top * Bottom * Side
- 63. Core • A solidbody of sand used to form a cavity of desired shape and size in casting
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- 66. Permanent Mould • Mouldis not destroyed after each casting. • Economical –High production rate • Used for low melting point material • Better dimensional accuracy , surface finishing • Less skilled labour • 2.4 mm thickness
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- 68. Die casting orpressure die casting • Liquid metal injected in to permanent mould under pressure.
- 69. Cold chamber diecasting • I
- 70. Hot Chamber diecasting • I
- 71. Centrifugal casting • Rotatingthe mould at a high speed with molten metal. • Adv. – impurities separation • Better dimensional accuracy • Proper directional solidification •
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- 77. Blow holes andcold shut • I
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- 79. Cupola • Furnace usedfor melting of cast iron.
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