hand molding demonstration process

HAND MOLDING DEMOSTRATION PROCESSGONZALVO, Zaira D.

Different tools used in Hand Molding Ramming Venting Sprue making Riser putting Putting powder in parting line Gate Making Cores placement Safety and Precautions

MOLDING is the process of manufacturing by shaping

pliable raw material using a rigid frame

TOOLS USED IN HAND MOLDING

TOOLS USED IN HAND MOLDING

o FLASKS are wood or metal frames in which the mold is made.

BELLOWS are used to blow excess parting materials from the pattern and also to blow loose sand and dirt from the mold cavity.

TOOLS USED IN HAND MOLDING RIDDLES are used for sifting the

sand over the surfaces of the pattern. The size of the riddle is given by the number of meshes to the inch.

RAMMERS used to compress the moulding sand

TOOLS USED IN HAND MOLDING STRIKE-OFF BAR are used

to scrape the extra sand from the top of the cope or drag after ramming.

DRAW SPIKES are tapered steel rods having a loop at one end and a sharp point at the other. to draw pattern from the

mold

TOOLS USED IN HAND MOLDING TROWELS are made of

iron and wooden handle. for making joints for finishing, smoothing cutting ingates Giving shape Repairing molds

VENT WIRES – Thin steel rod or wire used for making holes(vents) in the rammed sand molds

TOOLS USED IN HAND MOLDING SWAB is a small brush

having long hemp fibers used for applying water around the edges of a pattern

SHOVEL is like a rectangular pan fitted with a handle used for mixing the molding sand and for moving it from one place to the other.

TOOLS USED IN HAND MOLDING CLAMPS are used to hold

the cope and drag of the complete mold together so that the cope may not float or rise when the molten metal is poured into the mould.

LIFTERS are used for removing loose sand from deep cavities in molds.

TOOLS USED IN HAND MOLDING SPIRIT LEVEL is used

to check that the sand bed, moulding box or table of moulding machine is horizontal.

SPRUE CUTTERS used to cut openings in the sand mold for downsprues 

TOOLS USED IN HAND MOLDING GAGGERS are iron rods

bent at one or both ends. These are used to reinforce the moulding sand in the top portion of the moulding box and for supporting hanging sand

CHAPLETS are metal supports used to hold a core in place when core prints are inadequate.

TOOLS USED IN HAND MOLDING SLICKS are used for

repairing and providing finishing to mold surface and edges after the pattern has been withdrawn. Heart and leaf slick,

Square and heart slick, spoon and bead slick, Heart and spoon slick, Leaf and spoon slick

TOOLS USED IN HAND MOLDING GATE CUTTERS are

pieces of sheet brass bent to a semicircle on one edge. They are used to cut the in gate in the drag leading from the base of the sprue to the mold cavity.

TOOLS USED IN HAND MOLDING RAPPING PLATE (OR) LIFTING PLATE is used to

facilitate shaking and lifting large pattern from the mold.

RAMMING

RAMMING Hand ramming is the method of packing sand

to produce sand mold.Uniform throughout the moldFirm enough to consolidate the sand,

but not hard enough to reduce the porosity which may prevent gases from escaping when the mold is poured.

Never strike the pattern forcibly because it may damage it or dislodge the pattern from its position.

RAMMING Sprinkle some parting dust or graphite powder on

the pattern. Use the riddle to sift some molding sand over the

pattern until it is covered. Ram more sand in place over and around the

pattern, eventually filling the drag with rammed sand above the top edge.

VENTING

VENTING Venting is a process that is used to remove

trapped air from the closed mold and volatile gases from the processed molten material.

Concept: provide many pathways to allow trapped air and volatile gases to escape from the mold quickly and cleanly

VENTING Pathways should

lead directly from the edge of the cavity image of the mold, to the outside atmosphere surrounding the mold

to be deep enough to let air and gases out easily, but not deep enough to allow the molten metal to escape through them.

VENTING There are three major dimensions for the

vent. 1. “D”- Depth2. “W”-Width - 1/8 inch wide or more. 3. “L”- Length - minimum of 0.030 inch and a

maximum of 1/8 inch

VENTING HOW MANY VENTS ARE NEEDED?

have at least 30% of the perimeter of the cavity image in vents, equally spaced around that perimeter

Vent the runner

SPRUE MAKING

SPRUE MAKING Sprue- the hole through which plastic or

metal is poured or cast into gate or reservoir and then into the mold.

SPRUE MAKINGPlace a sprue pin in the sand adjacent to

the pattern and about one inch away from it.The location of sprue is not important to

symmetrical patterns because metal can be fed anywhere around the edge with equally good results

If pattern has some thin sections which are hard to fill completely, 2 or more sprues may actually be required

RISER PUTTING

RISER PUTTING Riser (Feeder Head)

A passage of sand made in the cope during ramming

Molten metal rises in the riser after mold cavity is filled up

The metal compensates for the shrinkage as the casting solidifies

Size depends on the freezing ratio

RISER PUTTING Effective if:1. The riser cools after the casting, 2. The riser has enough material to

compensate for the casting shrinkage, and 3. the casting directionally solidifies towards

the riser.

PUTTING POWDER IN THE PARTING LINE

PUTTING POWDER IN THE PARTING LINE

A parting line, or seam in moldmaking is the place where two or more parts of the mold meet.

Parting Powder: is used to release cope from drag and over pattern preventing the molding sand from sticking and ruin the mould finishing.

(Talc, Graphite, Dry silica powder)

Dust bag

GATE MAKING

GATE MAKING Gate - is a channel which connects runner

with the mould cavity and through which molten metal flows to fill the mould cavity. - should not have sharp edges - thin cross section

GATE MAKINGThe Gating System

Minimize turbulent flow so absorption of gases, oxidation of metal and lessen the erosion of mould surfaces

Regulate entry of molten metalEnsure complete filling of mould cavityPromote temperature gradient within

casting so all sections could solidify properly

GATE MAKING Pouring Basin: where the molten metal enters

the mold. Down Sprue: Path from the pouring basin, where

molten casting travels; Tapered Sprue Base: Where the casting's inner cavity

begins. Ingate/Choke Area: Runners: Are passages that distribute the liquid

metal to the different areas. Main Cavity: The impression of the actual part to

be cast is often referred to as the main cavity. Vents: Assist in the escape of gases Risers: Risers are reservoirs of molten material.

GATE MAKING GATE DESIGN RULES

Gate symmetrically to avoid warpage Gate into thicker sections for better filling

and packing Gate long, narrow parts from an end for

uniform flowMultiple gates shorten flow lengthsLocate gates on either side of a weak core

CORES PLACEMENT

CORES PLACEMENT Core

used in casting and molding processes to produce internal cavities and reentrant angles.

Normally a disposable item that is destroyed to get it out of the piece.

CORES PLACEMENT Cores

Created from sand and a binder(resin) that cures through heat or gasification

Once prepared, they are set in place in the mold.

CORES PLACEMENT Cores

1. Horizontal Core- used in horizontal position always at the paarting line between two mold boxes

2. Vertical Core- set in it’s vertical position.• Top and bottom ends are supported in the

seats formed by the core prints in molding sand

3. Balanced core- has one core to maintain alignment

1. - often used to produce blind cavity4. Drop core (Stop-off core)- used when cavity

either above or below the parting line

CORES PLACEMENT5. Hanging core (cover core)- hangs vertically in the mold with no support at it’s bottom end

- mold cavity in the drag only

SAFETY AND PRECAUTION

SAFETY AND PRECAUTUION Wear clothing suited for the job, wear shoes with thick

soles Do not play with the tools and equipment Always see that work and cutting tools on any machine

are clamped securely before starting. Keep the floor clean of metal chips or curls and waste

pieces, put them in container provided for such things. Put tools always when not in use Think about what you are doing at all times. Focus on

the job at hand and the next step. Have all moves planned and rehearsed prior to any operation.

Educate yourself beforehand and always be careful of your own and bystander safety