Foundry Technology

Introduction” Foundry or casting is the process of

producing metal/alloy components of desired shapes by pouring the molten metal into a prepared mold and then allowing the metal to cool and solidify. The solidified piece of metal is known as a CASTING”

Different Sections in Foundry Pattern making Sand mixing & preparation Mould and core making Mould assembly & handling Melting Pouring Knockout & Shot blasting Fettling & finishing Heat treatment Inspection & testing

Metals and alloys commonly used in Foundries:

1. Ferrous2. Non-Ferrous

FERROUS:a. Cast ironsb. Steels

NON-FERROUS:c. Copper alloysd. Aluminium alloyse. Nickel alloys

Pattern Making• A Pattern is a model or the replica of the

object to be cast.• Except for the various allowances a pattern

exactly resembles the casting to be made.• A Pattern may contain projections known as

core prints if the casting requires a core and need to be made hollow.

Materials for making patterns:a. Woodb. Metalc. Plasticd. Plastere. Wax.

Types of Patterns:1. Single piece

pattern.2. Split piece

pattern.3. Match plate

pattern.4. Cope and Drag

pattern.

Molding materialsIt also known as foundry sands, it defined by eight characteristics:• Refractoriness • Chemical inertness• Permeability• Surface finish • Cohesiveness • Flowbility• Collapsibility• Availability/cost

Sand Mixing &PreparationThe main ingredients of any molding sand are:• Base sand Base sand is the type used to make the mold or core without any binder• Binder Binders are added to a base sand to bond the sand particles together• AdditivesThese are added to the molding components to improve dry strength Refractoriness surface finish cushioning properties

A Typical Composition of Molding Sand:

Molding Sand Constituent Weight Percent

Silica sand 92

Clay (Sodium Bentonite) 8

Water 4

SAND-CASTING

MOLDING:Sand placed

into bottom mold form & compacted

MOLDING: Pattern placed into mold

sand casting process. . .

First of all, mix the sand.

21THEN

SAND-CASTINGMOLDING: Add the top mold form

3

4 MOLDING: Fill top form with compacted sand.

A tube or pipe provides a path to pour the metal in

Pattern is still inside!

SAND-CASTINGMOLDING: Take the top mold off and remove pattern & pipe or post

5

6 MOLDING: Replace the top mold and fasten securely!

Pouring hole

In the middle of the sand is a cavity shaped like the pattern!

SAND-CASTING

7 CASTING: Pour the metal (container is filled from furnace immediately before you are ready to pour)

8 Wait for the metal to cool(minutes to days, depending on the size of the casting)

SAND-CASTING

8 SHAKE OUT: Break apart the two halves of the mold & take out the part—usually requires vibrating or striking the mold to break apart the sand

CLEANING. Sand is cleaned off the part, the “tab” where metal flowed in must be removed.

9

A copy of the pattern has now been made in metal

10 Mold forms are reused

11Sand is broken up, screened to remove debris and clumps, and sent for remixing

Sand Casting: Parts of a Sand Mold

Sand mold - opened

Sand mold - closed

Mixing moulding sand with binders & adhesives

Filling sand in moulding flasks

Melting furnace

Pouring molten liquid

Knock out

Heat treatment

Machining

final products of casting

Thank you