1.16 Metal Processes Flashcards

Question

State the feature of soldering

Answer 1

Process type: Addition Uses a filler material of a lower melting point than the metal being joined. Typically, solders are an alloy of tin and copper

Answer 2

Process type: Addition Pop riveting uses a rivet gun (or riveting pliers) and a rivet and pin. Good for where the underside of the joint is inaccessible

Answer 3

Process type: Wastage The milling machine can run in the x-direction (left and right horizontally), y-direction (forward and backward horizontally), and z-direction (up and down vertically) to cut slots, shape edges, or thread holes.

Answer 4

Process type: Wastage The workpiece is held with a three or four jaw chuck in the headstock whilst the cutting tool moves in two axes.

Answer 5

Process type: Wastage Uses oxy-acetylene gas and a special flame-cutting torch to deliver a very intense and focused flame above 3,500°C. Difficult to maintain a parallel line with high levels of tolerance

Answer 6

Process type: Wastage Plasma is a super-heated ionised gas that is electrically conductive. Plasma cutting generates a faster, cleaner cut than flame cutting

Answer 7

Process type: Wastage More accurate and uses less energy than plasma cutting but cannot cut the same thickness of the material Lower-powered lasers are used in schools and colleges to cut acrylic sheets and manufacture boards such as MDF and plywood.

Answer 8

Process type: Wastage Uses computer-controlled machines that stamp out sections of sheet material Suitable for small and medium-size production runs and it is normally used for processing metals from 0.5mm to 6mm thickness.

Answer 9

Self-tapping screws Machine screws Nut and bolt

Answer 10

1) Sheet metal is clamped over a die of the product that will determine the final shape of the pressing. 2) A hydraulic press pushes the die into the sheet metal. Cutting blades may be included to punch holes into the sheet and trim the excess from the edges. 3) The hydraulic die is lowered and the pressed sheet component is removed. 4) The sheet may be placed into further press forming machines for additional pressing, where the shape is complex.

Answer 11

1) A former called a ‘mandrel’ is put into the chuck. The sheet metal blank is held in place between the mandrel and the tail stock. 2) The roller tool is moved into the blank and is rotated with the mandrel. metal stock This starts to stretch the metal over the mandrel. 3) The roller tool is moved along the mandrel as pressure is maintained 4) The roller tool is moved to the end of the mandrel, while still maintaining contact with the blank. This finishes the shape of the product. 5) The finished product is removed from the mandrel. 6) Excess material is trimmed off following the spirring process.

Answer 12

1) The pressing blank is clamped over a deep drawing die using a pressure pad or clamping ring known as a retainer. 2) A hydraulic press moves the deep drawing punch to be in contact with the blank. It then pushes the blank into the die cavity to make a cup shape. 3) The ‘cup’ is then pressed further down through the deep drawing die to make the desired tube shape.

Answer 13

1 A die is made from cast tool steel (which resembles a mould) and this is secured to the top of an anvil. 2 Aram is also equipped with a die that resembles a mould. 3) The metal ‘billet’ to be forged is heated to above its recrystallisation temperature (the temperature below the melting point shape of the metal at which point it is possible to change the size and shape of the grains that make up the metal). This stops the product from work hardening as it cools, which would make it brittle. 4) Using tongs, the heated billet is placed by an operator into the anvil die, and the hydraulic ram is brought down with force. This makes the hot billet spread around the shape of the die. 5) The ram is lifted and the completed product removed for cooling and finishing.

Answer 14

1) A ‘pattern’ is made, usually from wood. This is a replica (sometimes divided into two halves) of the item that will be cast, and it is placed in the bottom of a steel box called a ‘drag’. The drag is then filled with sand which is packed or rammed in tight around the pattern and levelled. 2) The drag is turned over and a second box called the ‘cope’ is clamped into position over the top of the drag. The top half of the pattern is placed into this to mate with the bottom half of the pattern. Wooden stakes are positioned in the cope. These will form the sprue or runner, and riser later in the process. 3) Sand is packed into the cope around the runner, riser and pattern. A small depression is made on the surface around the sprue to make a pouring basin. 4) The cope and drag are separated, and the stakes and patterns are carefully removed. Connecting channels are cut to join the sprue to the pattern cavity, and from this to the riser. The cope and drag are then reassembled and the mould is ready for pouring to begin. 5) Small metal spikes may be inserted and removed to make vent holes. These will allow gases from the casting process to escape. 6) The molten metal is poured into the pouring basin. It flows down the runner, into the cavity. When the cavity is full, the molten metal flows up the riser, indicating to the worker that the cavity is full. Once cool, the sand is removed to reveal the casting. The runner, channels and riser are cut off with a hack saw and the casting is ready for machining.

Answer 15

1) An exact replica or pattern of the product to be cast is made using wax. (This might be made using a master mould machined in steel or aluminium if the product is to be batch produced.) Where several items are to be cast, further wax patterns might be joined together in a ‘tree’, including a replica of the runner that will be used to pour the molten metal in. 2) The wax pattern is dip coated with a refractory clay. It is then fired in a kiln to bake the clay hard. The wax is burned away, leaving a hollow clay mould. 3)Molten metal is poured into the clay mould. 4)Once the metal has filled the mould, it is allowed to cool. 5)The clay mould is then broken away, revealing the casting. 6)The runner and any connecting channels are machined off.

Answer 16

1) A mould is made from MDF, plywood or high density modelling foam. If made from MDF or plywood, the mould might be laser cut or cut with a fret saw. The mould will include a sprue or runner which will be used to pour the pewter into. 2) The mould is sandwiched between two pieces of MDF and clamped together. The top of the mould will be level with the top of the side pieces. 3) The pewter is melted in a ladle and then ladled into the sprue. 4) Once the casting is cooled, it is removed from the mould. 5) The sprue or riser is removed with a junior hacksaw. 6) The casting is then filed, and cleaned up using abrasive wet and dry paper. 7) The casting would then be polished.

Answer 17

1 The metal is prepared by grinding an angle on the edges of the two pieces to be joined to form a ‘v’ shape. This is done to ensure that the weld runs through the entire thickness of the metal. 2 The joint area is heated to form a melt pool and at the same time, a steel filler rod is introduced to the joint area. The melt pool is extended to form a continuous bead along the length of the joint. The molten metal will flow to the hottest part of the metal, therefore by moving the torch along the joint line, a continuous seam is formed.

Answer 18

1 The material to be joined is cleaned and degreased. 2 The two pieces are clamped together. 3 A flux is applied (this helps to prevent the joint from oxidising). 4 The joint is heated using an oxy-acetylene or gas/air torch to a temperature of approximately 850 °C. 5 The brazing rod is applied to the joint area. The brazing ‘spelter’ will flow along the joint by capillary action to the hottest part, so it can be made to follow the joint line by manipulating the torch.

Answer 19

1 The metal is cleaned and degreased. 2 The joint area is wired up or clamped. 3 The metal is heated up to the melting point of the solder. 4 The solder is added to the metal. The solder will flow along the joint using capillary action. 5 The metal is cleaned to remove any flux residue.