daily_snaps

Photographs of the process
Pattern Making
	Pattern Making From customer's drawings we have to manufacture a pattern generally from wood, although we can use metal, fibreglass or polystyrene. Allowances are made on the sizes of the pattern to allow for the shrinkage of metal as it cools. Iron contracts at 1 mm every 100 mm, steel 1 mm for every 60 mm. Each metal has its own rate of contraction and the pattern is built taking this into account. Where the finished casting is to be machined allowances of 5 mm to 15 mm are made to add this extra metal onto the correct areas.
	This is a pattern, shown upside down as used on the vehicle, to make a 1 tonne counterweight casting for a JCB forklift truck. We were involved at the initial design stage and produced castings from a flimsy model for sampling. Adjustments were made to fit the casting to the auxiliary engineering of different motor types, tyre sizes etc. 37 minor alterations to the pattern were made to establish fitting and cosmetic design. This casting forms the rear end of the 'teletruc' forklift. The bumper area is cast in and light clusters, insignia, tow hole all forming part of the design. www.jcb.co.uk
	Pattern shown red and black. The sample casting looking gold. The core box ( black and white ) is filled with sand to produce a core, which will take out the centre of this casting. The red on the pattern depicts what will be metal and the black is where the core will go.
	Cores Cores made in sand and oil mix. They are in an oven where they will be baked hard so they can be handled and resist the weight of iron when casting. The pattern and core boxes can be used repeatedly to make moulds and castings.
	A mould made in the floor. The pattern has been removed and the shape it has left in the sand is painted with a ceramic ( white ) to stop the heat of the metal from turning the sand to a glassy material and sticking to the casting when the molten metal is poured in.

Photographs of the process
Pattern Making

Pattern Making

From customer's drawings we have to manufacture a pattern generally from wood, although we can use metal, fibreglass or polystyrene.
Allowances are made on the sizes of the pattern to allow for the shrinkage of metal as it cools. Iron contracts at 1 mm every 100 mm, steel 1 mm for every 60 mm.
Each metal has its own rate of contraction and the pattern is built taking this into account. Where the finished casting is to be machined allowances of 5 mm to 15 mm are made to add this extra metal onto the correct areas.

This is a pattern, shown upside down as used on the vehicle, to make a 1 tonne counterweight casting for a JCB forklift truck. We were involved at the initial design stage and produced castings from a flimsy model for sampling. Adjustments were made to fit the casting to the auxiliary engineering of different motor types, tyre sizes etc. 37 minor alterations to the pattern were made to establish fitting and cosmetic design. This casting forms the rear end of the 'teletruc' forklift. The bumper area is cast in and light clusters, insignia, tow hole all forming part of the design.
www.jcb.co.uk

Pattern shown red and black.
The sample casting looking gold.
The core box ( black and white ) is filled with sand to produce a core, which will take out the centre of this casting.
The red on the pattern depicts what will be metal and the black is where the core will go.

Cores

Cores made in sand and oil mix. They are in an oven where they will be baked hard so they can be handled and resist the weight of iron when casting. The pattern and core boxes can be used repeatedly to make moulds and castings.

A mould made in the floor. The pattern has been removed and the shape it has left in the sand is painted with a ceramic
( white ) to stop the heat of the metal from turning the sand to a glassy material and sticking to the casting when the molten metal is poured in.

	MOULDING The box on the right is a mould with both the top half and bottom half closed. The circular hole in the top is where the metal will be poured in to the mould. The box on the left is without the top and shows the impressions in the sand made by the pattern. One of the patterns is on the box on the right. The metal will flow into the cavity, when cool we will have a solid casting.
	This is another mould formed in the ground. It was originally designed as a fabricated beam to be welded. However, because it was so thin the steel was twisting under the heat of the welding. It is 5300 mm long. As iron cools the metal contracts, this causes the casting to bend and lift at the ends, so we shape it in the mould using camber to bend the mould so the casting will come straight when it cools.
	The person in the light shirt is stood in a mould for a stator made for GEC. The core to take out the centre of the casting is in the crane behind his head. The mould is contained in a metal box, the sand wall being about 75 mm thick. Pressures created when casting require a box to hold the sand in position.
	The top half of the core is lowered into the mould and checked for being central. The cores and sides of the mould have been painted with coatings to give the castings a smooth surface when cast. There were 18 cores used to take out the centre and provide various access points for the electrics and panels to be fitted to the finished casting.
	One of our larger moulds, a gate valve casting for the water industry. The bits by his feet are the strengthening ribs of the casting. The circular parts either side of the moulder will be cored out and form flanges where the pipes will be attached either side of the valve. The shut off blade will travel from where his right hand is and block the flow between the two pipe flanges. When the core is placed in the mould it will leave a wall thickness of 40 mm for the metal to flow into.

	MELTING We melt by using electric furnace and a cupola ( blast furnace ). See Melting Page The cupola uses coke to melt with and an air blast to superheat the coke to approx. 1550-1600 C The coke is Cwm coke from Wales. It is about 150 mm cube in size and we use around 10% weight of metal to melt with.
	Recycling Scrap metal consisting of old brake drums, engine blocks and other quality produced parts are supplied in sizes suitable for handling. Metals such as aluminium are removed from the scrap as it may cause gas holes in the finished castings. Copper left in will strengthen the metal.
	Charging the Cupola The materials for charging include steel to dilute carbon and silicon levels, coke for melting, pig iron for increasing the silicon level, manganese for reducing sulphur in the iron and pictured at the back limestone for balancing the acidity of liquid contents as the iron melts through the coke while also increasing the fluidity of the slag.
	Through the Looking Glass Holes in the side of the cupola (tuyeres) allow the air blast to enter the furnace. This view is into the heart of the furnace. The darker edging is the clay lining of the furnace. The golden/white blocks is the coke and the dark spots silhouetted are drops of molten metal.
	The Slag Hole Slag floats on the top of the metal, as the metal level rises the slag pours out through a hole 700 mm above the base of the funace. The picture shows just the air blast coming out of the slag hole before the slag reaches that level.
	The Tapping Hole At the bottom of the cupola is the tapping hole. This is where the iron is removed from the furnace. The hole is made about 40- 45 mm diameter and is sealed with a clay bod. The bods can be seen attached to rods hanging off the wall on the left. When the metal has filled to a certain level, about 600 Kgs. the hole is opened by breaking the clay. The metal flows down the trough and into the ladle. The ladle shown holds 2 tonne and is removed to the moulds by a crane. When all the metal from 1 batch is out the hole is closed using a new clay bod.
	Testing To test the metal to see it's grade and whether an adjustment is needed to the compositon we take a sample of metal from the stream when it is tapped from the furnace. Additions will comprise of silicon and graphite to 'seed' the iron crystals to promote a fine grained iron. The sample is cast into a wedge shaped mould 150 mm long.
	The test sample is removed from the mould as quickly as possible and whilst still glowing is chilled in water. This is for us to see the effect the additions have on the cooling rate and the formation of 'grey' iron with free graphite, which is easily machined and chilled iron ' white' which is a cabide and hard to machine.
	The Sample The sample is about actual size and shows if we were to cast a casting thinner than 8-10 mm with this metal the iron would cool white and be too hard to machine. Above that thickness the casting will be grey with free graphite giving a natural lubricant to aid machining.
	The Cast When we have sufficient metal of the right grade. The ladle is taken by crane to the mould. When the temperature is right it is poured in to the mould.