Moulding work is a basic need to almost every manufacturing process. It is a highly skilled profession. To carry out his craft the moulder has to apply his skill to the vision of the designer and draftsman, the art of the sculptor, the preciseness of the machinist and the exactness of the mathematician. As a result, the moulder has an unchallenged position in the industrial progress in the world.
Foundry work deals with the making of moulds, melting the metal and pouring of these metals into moulds to form castings. Industrial foundries are often identified according to the type of metal used in the pouring. Foundries which specialize in casting brass, bronze, aluminium and white metal are classified as nonferrous foundries. A foundry which cast principally grey cast iron, steel and malleable cast iron is classified as ferrous or iron foundry.
Types of Moulding Tools
Moulders Flask – The box like container in which the sand mould is made, is called a flask. Flasks are made entirely of wood, of wood with metal fittings, or entirely of metal. The flask is generally made in two parts; the bottom part is called the drag and the top part the cope. The drag is fitted with pins which fit into corresponding holes in the ears of the cope.
A three-part flask made up of a cope and drag with the addition of a third section called a check is used for some complicated moulds. Wooden flasks arc often avoided in industrial foundry because excessive usage makes them useless in a relatively short time.
Moulding Board – A moulding board is needed at the bottom and top of the mould. The size of moulding board is governed by the size of the flask with which it is to be used. Moulding boards are made either of metal or wood. Steel boards are more expensive, but will last longer than those made of wood. In either case the surface of the board must be smooth and flat.
Sprinkler – A common ten-quart garden watering can with a rose head sprinkler is ideal for wetting down and tempering the moulding sand. The rose sprinkling head should be detachable for easy cleaning.
Shovel – The foundry shovel is used for mixing and tempering the moulding sand. A square blade shovel with ‘D’ handle is the most practical.
Riddle – Foundry riddles are used by the moulder to shift the foundry sand to ensure an even deposit of fine moulding sand over the pattern. Riddle frames are generally round, and their size is denoted by the diameter of the frame and the coarseness of the wire screen. A No. 10 mesh has ten openings per linier inch. For general purpose moulding, a riddle with No. 12 or No. 14 mesh is recommended.
Rammer – Foundry rammers are often used in pairs for packing or ramming the sand into the mould. The moulder uses one in each hand as he rams up the mould. The rammer is generally made up of hard wood with a cylindrical butt about 3″ in diameter. The wedge shaped peen is used to force the land sideways in the flask.
Moulder’s Trowel – The moulder’s trowel is used in the foundry to smooth and patch large surface. In the mould. The blade is made of high quality steel, and has either a rounded or square point.
Slicks, Spoons, Lifters and Cornering Tool – The moulder makes use of variety of various shaped tools for fine patching and smoothing operations on the mould after the pattern has been removed. For removing particles of sand from recess in the mould, a. lifter is used. The lifter may also be used to make mould repairs in restricted places. Corner tools are used to repair corners on the inside or outside the mould.
Strike Off Bar – The strike off bar is a piece of metal or wood with a straight edge. The length of the strike off bar should be somewhat longer than the diagonal across the flask. It is used by the moulder to strike off the excess sand at the top of the cope or the bottom of the drag so that the moulding board will fit flat on the flask.
Vent Wire – Moulds must be vented to permit gases to escape while the molten metal is being poured. A vent wire is the tool used to make a series of small holes for this purpose over the mould.
Gate Cutter – A small piece of tin plate shaped serves as a tool for cutting gates and runners in the mould. It should be made from a thin piece of sheet about 4 square inches.
Bulb Swab – The bulb swab is used to paint water on the corners of the mould before the pattern is removed. This helps to prevent the mould from breaking while the pattern is being drawn. The rubber bulb is filled with water and squeezed as the brush is drawn along the mould.
Shake Bag – The shake bag is used to dust the parting compound on the mould. This can be easily made from a loosely woven cotton cloth.
Crucible – A crucible is a clay or graphite container in which metal is melted and transported to the mould. Crucibles vary in size from the smallest, which will hold but a few ounces,” of metal, to those which are designed to hold several hundred pounds. The capacity of crucible in pounds is determined by the weight of the molten metal which it will hold. Aluminium weighs less than iron of equal volume. A good example of crucible of standard size is No. 40 Crucible, which will hold approximately 40 pounds of aluminium.
Ladles – A ladle differs from a crucible in that it is constructed of pressed steel or riveted steel plate and is usually lined with fire clay. Molten metal is transferred from the furnace to the ladle and hence to the moulds. The most commonly used ladle in the shop is the hand type. It resembles a bucket with a removable long handle shank.