1 / 11

METAL CASTING LECTURE 12

METAL CASTING LECTURE 12. CASTING. Basically involves i. Pouring molten metal into a mould patterned after the part to be made WITHOUT TURBULANCE , SERIES OF EVENTS TAKES PLACE INFLUENCE SIZE, SHAPE, UNIFORMITY OF THE GRAINS FORMED,

lebel
Télécharger la présentation

METAL CASTING LECTURE 12

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. METAL CASTING LECTURE 12

  2. CASTING Basically involves i. Pouring molten metalinto a mould patterned after the part to be made WITHOUT TURBULANCE , SERIES OF EVENTS TAKES PLACE INFLUENCE SIZE, SHAPE, UNIFORMITY OF THE GRAINS FORMED, AND THUS THE OVERALL PROPERTIES. ii. Allow it to cool HEAT TRANSFER DURING SOLIDIFICATION iii. Remove from the moldINFLUENCE OF THE TYPE OF MOULD MATERIAL SIMILARITY WITH POURING CAKE MIX INTO A PAN

  3. POURING CAKE MIX INTO A PAN (MOULD) & BAKING IT*SELECT THE KIND AND SIZE OF PAN, *CONTROL THE COMPOSITION OF THE MIX, * CAREFULLY POUR THE MIX, * SET THE PROPER BAKING TEMPERATURE, * SET THE TIMER FOR PROPER BAKING TIME, * LEAVE THE CAKE IN THE MOULD FOR A CERTAIN AMOUNT OF TIME BEFORE REMOVING.(CASTING OF PLASTICS & CERAMICS - DIFFERENT)

  4. Knowledge of certain fundamental relationships is essential to produce good quality economic castingsThis knowledge helps in establishing proper techniques for mould design and casting practice.Castings must be free from defects, must meet the required strength, dimensional accuracy, surface finish

  5. ADVANTAGES OF CASTING PROCESS • Process is cheap • More suitable for mass production • Most suitable for manufacturing complex/complicated/intricate shaped products. • Large parts weighing several tonnes and also small components weighing a few grams can be cast. • No limitation on the size of component. • Directional properties absent in castings. Components with uniform properties as well as with varying properties at different locations can be cast. • By use of cores, saving in machining of holes achieved. • Internal stresses are relieved during solidification in many types of castings. • Even some materials which cannot be made by other processes made by casting: eg. Phosphor-Bronze.

  6. Outline of production steps in a typical sand casting operation Moulding - pattern making - Core making - Gating system Mould Sand Melting Pouring casting Heat Treat Clean Inspect Furnaces Solidification Shakeout Addl. Heat Treatment Defects, pressure tightness, dimensions

  7. PATTERN • Model of a casting constructed such that it forms an impression in moulding sand

  8. PATTERN • 1st step- Prepare model (pattern) Differs from the casting Differences Pattern Allowances. • To compensate for metal shrinkage, • Provide sufficient metal for machining • Easiness in moulding • As Shrinkage allowance, Draft allowance, Finishing allowance, Distortion or camber allowance, Shaking or rapping allowance

  9. MATERIAL • WOOD. • METAL Al, CI, Brass, 3.For special casting processes, Polystyrene which leaves mould as gas when heated also used. Types- many Simple-Identical patterns; Complex, intricate- with number of pieces. Single or loose piece; Split; gated; Match Plate; Sweep; Segmental; Skeleton(frame, ribbed), skell; Boxed Up; Odd shaped etc. Sketches

  10. Material 1. WOOD. (+) Cheap, easily available, light, easiness in surfacing, preserving (by shellac coating), workable, ease in joining, fabrication (-) Moisture effects, wear by sand abrasion, warp during forming, not for rough use. Must be properly dried/ seasoned, free from knots, straight grained Egs. Burma teak, pine wood, mahogany, Sal, Deodar, Shisham, Walnut, Apple tree

  11. 2. METAL: For durability, strength Egs: Al alloys, Brass, Mg alloys, Steel, cast Iron for mass production (first, wooden pattern is made, then cast in the metal) Type of material depends on shape, size, number of castings required, method of moulding etc.

More Related