1.4 Forming, redistribution and addition processes Flashcards
1
Q
What are the 3 paper and board forming processes?
A
1 Die cutting and creasing
2 bending
3 laser cutting
2
Q
What are die cutters used for?
A
To cut out paper or card ‘nets’ or ‘developments’. which, when folded and assembled, will form a 3D shape such as a box.
3
Q
What is the process of die cutting and creasing?
A
1 Die cutters use a plywood substrate board into which steel cutting dies and creasing rules are inserted.
2 Rubber pads fixed to the press help to prevent the paper or card sticking as the press moves up or down.
3 The stock material is placed under the board, and aa press pushes the board into the board material, which then cuts out the net.
4 Where parts of the net are to be folded, the creasing rules score the paper or card. The creasing rules are not as high as the cutting die, and they are also blunt, so they do not cut the stock material.
4
Q
What is the papers and board process of bending?
A
1 The stamped-out net is placed onto a folding table.
2 Some die cutting presses might be equipped with moving parts that help to bend or fold parts of a net automatically.
3 Some of the trickier finishing might be done by hand.
5
Q
Why is the use of lasers becoming more common when manufacturing paper and boards prototypes?
A
Due to their speed, accuracy and the high level of detail that is possible. They are also very flexible
6
Q
What are the 10 polymer processes?
A
1 vacuum forming
2 thermoforming
3 calendering
4 line bending
5 lamination (lay-up)
6 injection moulding
7 blow moulding
8 rotational moulding
9 extrusion
10 compression moulding
7
Q
What type of production does vacuum forming use and why?
A
It is normally limited to to small-scale batch production due to it being a slow process.
However, if a larger scale of production is required, moulds can be made from cast and machined aluminium.
8
Q
What products are made using vacuum forming?
A
lightweight trays
box inserts and liners
coffee cups
yoghurt pots
9
Q
What is the process of vacuum forming?
A
- The mould is placed on the bed of the machine, which is called the platen. The platen is lowered to the bottom of the machine.
- Polymer sheet is clamped over the mould and a heater is pulled over the polymer sheet.
- When the polymer sheet has softened, the platen is raised into the polymer and the heat is removed.
- The vacuum pump is switched on, which sucks the polymer onto the mould.
- Once the polymer has cooled and returned to a solidified state, the platen is lowered and vacuum switched off.
- The mould is removed from the moulding. Excess polymer is then trimmed off.
10
Q
What products are made from thermoforming?
A
bath
fruit punnets
cake boxes
sandwich boxes
11
Q
What is the process of thermoforming?
A
A very similar process to vacuum forming, except there is an additional mould that is pressed onto the surface of the polymer sheet at the same time as the vacuum is applied, sucking the polymer down on to the mould below. The two moulds trap the softened polymer in between them, giving extra detail to the moulding.
12
Q
What products are made using the calendering process?
A
thin polymer sheet and film
13
Q
What type of production system does calendering use?
A
continuous
14
Q
What is the process of calendering?
A
- It works by heating pellets of thermoplastics so that it melts into a dough-like consistency.
- It is then extruded between a series of heated rollers so that it becomes squashed and stretched to make it thinner.
- It is then finished on colling rollers, before being chopped into standard stock sheet sizes, or in the case of polymer film, it is rolled up for storage and distribution.
15
Q
What products are made using line bending?
A
acrylic boxes
shelves
point of sale displays
16
Q
What type of production is line bending suitable for and why?
A
one-off or limited batch production because it is quite slow and is a labour intensive process.
17
Q
What is the process of line bending?
A
- Turn on the strip heater.
- Place the thermoplastic on the strip heater, aligning the heated strip with where you want the bend.
- Ensure that you keep turning over the plastic to heat both sides evenly and avoid burning the plastic and making it bubble.
- Once the plastic is hot enough to bend easily, place it in the jig to create the required angle for the product and allow it to cool.
18
Q
What products does the lamination process make?
A
3D products from fibre-glass composites such as glass-reinforced plastic.
boats
yachts
kayaks
trains
19
Q
What is the process of lamination for moulding glass-reinforced plastic?
A
- A mould or former in the shape of the product is prepared. This might be made from timber, manufactured boards or high density foam.
- The mould is coated with a release agent such as wax or PVA, or is covered with parcel tape.
- A top layer of gel coat is applied. The gel coat of polyester resin often mixed with a pigment to give a colour to the moulding. The resin might also have additives included to prevent degradation from UV and hydrolysis.
- Fibreglass matting is cut to size and laid over the former. Polyester resin is brushed onto the matting and a small roller is used to push out any air bubbles that may form and to smooth out the matting (this process is called stippling). The matting is available in a range of stock forms including chopped strand, woven and ‘tissue’, which is a fine grade matting for covering the surface.
- Step 3 is repeated until the desired thickness is achieved, and fine tissue matting is used on the top layers. A vacuum bag may be used to compress the layers of GRP before it sets.
- The GRP is allowed to set.
20
Q
What products are injection moulded?
A
vacuum cleaners
clip fastenings
screw posts
battery housing
circuit board holders
(complex parts)
21
Q
What type of production does injection moulding use and why?
A
large-scale mass production or continuous production, due to the high costs of the equipment and the moulds.
22
Q
What is the process of injection moulding?
A
- Thermoplastic granules are poured into the hopper.
- An archimedian screw is rotated by a motor. This pulls the granules through the chamber and past electric heaters.
- The heaters melt the granules of polymer.
- When a sufficient charge if polymer has melted and formed at the end of the screw, a hydraulic ram forces the screw thread forward. This injects the polymer into the mould.
- The mould is water cooled, which enables the molten polymer to harden quickly.
- The mould opens and ejector pins push the moulding out.
- Any excess polymer is trimmed off the moulding. Formers and jigs may be used to maintain the dimensional accuracy of the moulding while it cools and hardens completely.
23
Q
What products use the blow moulding process?
A
bottles
wide range of hollow products
24
Q
Which polymers are used for blow moulding?
A
PET
LDPE
HDPE
PP
25
What type of production does blow moulding use and why?
continuous production due to the high set-up costs associated with the equipment and moulds
26
What is the process of blow moulding?
1. The polymer is fed into the hopper.
2. Sn Archimedean screw pulls the polymer through a heated section, melting the polymer.
3. The melted polymer is extruded as a tube, which is called 'parison'.
4. The mould sides close around the parison and air is injected into the mould, forcing the polymer to the sides.
5. The polymer is allowed to cool for a few seconds, the mould opens and the finished bottle is ejected.
27
What are the two types of blow moulding?
parison
preform
28
What types of products are made using rotational moulding?
traffic cones
kayaks
water tanks
children's play equipment
29
What types of polymers are used for rotational moulding?
HDPE
PP
30
What type of production is normally used for rotational moulding and why?
large-scale batch or mass production due to the high set-up costs
31
What is the process of rotational moulding?
1. Polymer powder or granules are loaded into a mould, which is clamped and sealed.
2. The mould is transferred to an oven where it is heated to 260-370 degrees Celsius, depending on the polymer being used. The mould is rotated slowly (fewer than 20 rotations per minute) around two axes, and as the polymer is heated, it coats the inside of the mould.
3. Once the polymer has achieved the correct thickness, the mould is cooled. Usually a fan and/or water is used to cool the polymer.
4. When the polymer has solidified, the part will shrink slightly, allowing it to be removed.
32
What products are made from extrusion?
solid rod
hollow tubes
angles sections
33
What type of production does extrusion use?
Continuous
34
What is the process of extrusion?
1. Polymer granules are loaded into the hopper.
2. the Archimedean screw moves the polymer granules past the heaters.
3. The heaters soften the polymer.
4. When sufficient polymer has melted, the hydraulic ram pushes the Archimedean screw, forcing the polymer through a steel die. The shape of the die determines the shape of the extrusion.
5. The extrusion may be supported by rollers as it leaves the die and is cooled by water or air.
6. The extrusion is then cut to the desired length.
35
What polymers are used for compression moulding?
thermosetting polymers such as urea formaldehyde and melamine formaldehyde.
36
What products are made from compression moulding using urea formaldehyde?
electrical light fittings
switches
electrical plugs
37
What products are made from compression moulding using melamine formaldehyde?
polymer plates, bowls and mugs for picnic sets
children's table sets
38
What is the process of compression moulding?
1. A 'slug' of pre-weighed thermoset polymer is inserted into the pre-heated moulds.
2. The moulds are closed and hydraulic pressure is applied. The pressure ensures that the polymer takes the shape of the mould.
3. The moulds remain closed while cross-linking takes place and the thermoset 'cures'.
4. When the moulding has cured, the machine opens and the product is removed.
5. Excess polymer known as 'flash' is removed.
39
What are 7 metal forming processes?
1 press forming
2 spinning
3 cupping and deep drawing
4 drop forging
5 wrought iron forging
6 bending
7 rolling
40
What type of products is press forming used for?
bar body panels, metal seats, boxes, containers
41
What type of metal is used for press forming and why?
carbon steel and aluminum because of their malleability and ductility
42
What type of production does press forming use and why?
mass production or large-scale batch production due to the cost and complexity of making the dies
43
What is the process of press forming?
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 presses sheet component is removed.
4 The sheet may be placed into further press forming machines for additional pressing, where the shape is complex.
44
What type of products are made from spinning?
stainless steel kettles, saucepans or other products with radial symmetry.
45
How can spun products be identified?
Parallel lines that are formed on the surface of the metal during the process
46
What type of production is used when spinning metal products?
Spinning is typically used in mass production, and can be set up using computer controlled machines so that thousands of identical products can be made. However, as the formers are relatively simple, it can be used in batch production, particularly where dome-shaped items need to be made but the quantity required does not justify the costs associated with press forming.
47
What is the process of spinning?
1 A former called a 'mandrel' is pout 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. This starts to stretch the metal over the mandrel.
3 The roller tool is moved along the mandrel as pressure is maintained against the rotating blank.
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 spinning process.
48
What products are made from cupping and deep drawing?
tube-like shapes such as fire extinguishers and high pressure aerosol cans.
49
When does it change from cupping to deep drawing?
It is considered deep drawing when the depth of the pressing exceeds the diameter.
50
What type of production is used for cupping and deep drawing and why?
mass or continuous production is identical items due to the high setup costs
51
What is the process of cupping/deep drawing?
1 The pressing blank is clamped over a deep drawing die using a pressure pad or clamping ring known as a retainers.
2 A hydraulic press moved 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.
52
When do manufacturers use drop forging/
When the finished product needs to be tough (impact resistant) and hard. Drop forging allows hot metals to be formed and maintains the internal grain structure and thus the strength required.
53
What type of products are made through drop forging/
spanners, pliers and screwdriver shafts
54
What type of production does drop forging use?
Mass production due to the fact that the dies are dedicated to making one specific item.
55
What is the process of drop forging?
1 A die is made from cast tool steel (which resembles a mould) and this is secured to the top of an anvil.
2 A ram is also equipped with a die that resembles a mould.
3 The metal 'billet' to be forged is heated to above its recrystallisation temperature. 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.
56
What does it mean by the recrystallisation temperature of a metal?
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
57
What type of production does wrought iron forging use?
It is suitable for one-off or limited batch production because there is no requirement to make formers or dies to shape the product.
58
What is the process of wrought iron forging?
1 The wrought iron is heated in a gas or coke-fired forge.
2 It is then shaped by holding it with tings, hammering it over an anvil or using tool such as scroll formers or twisting bars.
59
What type of production does bending use?
Can be done as a one-off production method. However, in industry where press brakes are used, it is more typically used in large-scale batch production
60
What is the process of bending?
1 Clamp the stock metal between a matching punch and die.
2 A hydraulic, pneumatic or mechanical brake holds the metal sheet or plate, and lowers the punch to bend the material to shape.
3 Modern press brakes use a device known as a back gauge to accurately position the piece of metal, so that the brake bends the metal in the correct place.
61
What types of dies used in press brakes are used in bending metals?
V shaped
90 degree
radius
62
What are the 2 types of rolling?
1 hot rolling
2 cold rolling
63
What is hot rolling?
When the metal has been heated above its recrystallisation temperature.
64
What is cold rolling?
When the metal has been heated below its recrystillisation temperature.
65
What is metal rolling?
A metal forming process in which the stock metal material is passed through sets of rollers to reduce the thickness of the material.
66
What is the advantage of hot rolling?
It results in material with mechanical properties that are uniform throughout the sample. It will not have any deformation or stresses which could result in a fault in the material.
67
What is the disadvantage of hot rolling?
The surface is usually coated with carbon deposits, which have to be removed using acid pickling.
Hot rolled materials have a more generous tolerance applied to their dimensions because of the carbon deposits on the surface.
68
What is the advantage of cold rolling?
It results in a material that has a tighter tolerance because carbon deposits are not formed during the rolling process. The surface finish of cold rolled metal is therefore much better.
69
What type of products does cold rolling metal produce?
home appliances, filing cabinets, chairs, steel drums, electrical cabinets, containers, saucepans
70
What are the 4 metal redistribution processes?
1 sand casting
2 die casting
3 investment casting
4 low temperature pewter casting
71
What type of production does sand casting use and why?
one-off and batch production due to the process being slow and labour intensive and the moulds are only single use
72
What is a disadvantage of sand casting?
Sand casting does not give a very high-quality surface finish because the molten metal will pick up the grainy texture of the sand.
73
What is the process of sand casting?
1 A 'pattern' is made, usually from wood. This is a replica 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 spruce 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 hacksaw and the casting is ready for machining.
74
What metals are used in die casting?
aluminium
alloys of aluminium
zinc-based alloys
75
What type of production does die casting and why?
Large batch and mass production due to the complexity and cost of making the dies
76
What is an advantage of die casting?
produces castings with a very high-quality surface finish
77
What type of products are die cast?
alloy wheels, engine components, toy cars, collectible figures, door knobs and handles
78
What are the 2 types of die casting?
1 gravity
2 pressure
79
What is the process of gravity die casting?
It involves melting the metal and then pouring it into the mould. This process relies on gravity to help the metal to flow through the mould. As in sand casting, there is a runner and riser. The runner is used to pour the molten metal into the mould, while the riser will indicate when the mould is full. Once the metal is cool, the mould is opened and the casting can be removed.
80
What are the 2 forms of pressure die casting?
1 hot chamber
2 cold chamber
81
What is the process of hot chamber pressure die casting?
1 The molten metal is stored in a chamber which is part of the high pressure die casting machine.
2 A pneumatic or hydraulic plunger forces a 'shot' of molten metal through the 'goose neck' into the die.
3 Because this process uses high pressure, all of the mould is filled and it allows the find detail to be moulded.
4 The process is very fast because the molten metal is not stored separately and then transported to the casting machine.
82
Why cant aluminium be cast using hot chamber die casting?
It picks up iron from the steel chamber
83
What is the process of cold chamber pressure die casting?
1 The molten metal is kept separately in a melting crucible.
2 The molten metal is then ladled into the shot chamber, and a hydraulic ram forces the molten metal into the mould cavity.
3 When the metal has hardened, the mould opens and ejector pins push the finished casting out.
84
What is investment casting also known as ?
lost wax casting
85
What are some products that would be casted using investment casting?
jewellery, collectable figures, medical applications
86
What types of metals are used for investment casting?
stainless steel, brass, aluminium, carbon steels
87
What is the process of investment casting?
1 An exact replica or pattern of the product to be cast is made using wax. This might be made using a master mould machines 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.
88
What type of production does pewter casting use and why?
One-off production due to the fact that it is easy to make the moulds for pewter casting from a range of materials.
89
What is the process of pewter casting?
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 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 filled and cleaned up using a abrasive wet and dry paper.
7 The casting would then be polished.
90
What are the 7 addition/fabrication processes?
1 MIG welding
2 TIG welding
3 Oxy-acetylene welding
4 Brazing
5 Soldering
6 Riveting
7 Pop riveting
91
What does MIG welding stand for?
metal inert gas
92
What is MIG welding?
A fabrication process used to weld thin gauge metal (usually medium carbon steel) or aluminium (where aluminium electrode wire is used), particularly tube and box section.
93
Why is MIG welding suitable for thin gauge metals?
the heat generated by the electric arc is localised to a small area and if done correctly, the process will not burn through the metal or distort the surrounding metal.
94
When is MIG welding used?
joining tubular steel in products such as climbing frames, bike frames and vehicle exhausts
95
What is the process of MID welding?
1 MIG welding uses an electric arc to create heat which melts the joint area. A wire electrode (made from the same material being welded) also melts in the arc and fills the gap between the two pieces being joined.
2 The operator swirls the welding gun as they move it over the joint, to form a continuous bead of weld.
3 The electrode wire is stored on a reel and advances through the welding 'gun' as the trigger is pressed.
4 MIG welding uses an inert gas such as carbon dioxide or argon to form a 'flux' shield over the area that is being joined.
5 The gas shield replaces the oxygen at the joint area, which helps to prevent oxidisation that would be prevent the weld from forming properly.
96
What does TIG welding stand for?
tungsten inert gas
97
What metals are joined using TIG welding?
stainless steel and non-ferrous metals such as aluminium and copper or magnesium alloys
98
How do MIG and TIG welding differ?
TIG is an electric arc welding process that is similar to MIG, except that the electrode made from tungsten does not melt in the process. Instead, a separate filler rod is used. A gas shield of argon or helium is used to protect the weld area from oxidisation.
99
What are the advantages of using TIG welding over MIG welding?
the TIG process allows for greater control by the operator and more accurate, stronger welds can be created.
100
What is the disadvantage of using TIG welding over MIG welding?
The process requires higher levels of skill and it is quite a slow method.
101
Where would TIG welding be used?
fabricating stainless steel ladders for boats or swimming pools and stainless steel car exhausts
102
When is oxy-acetylene welding useful?
quick repair jobs or in remote locations where there is no electric power supply
103
What is the process of oxy-acetylene welding?
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. Thee 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.
104
What is brazing also known as?
hard soldering
105
What kind of products is brazing used on?
small items of furniture, a plant stand or ornamental light
106
What is the process of brazing?
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 degrees Celsius
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.
107
What is the process of soldering?
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
108
What is riveting?
A permanent joining method usually used to join sheet metal or plate
109
What is a rivet?
A metal fastener that has a 'head' at one end and a shaft or tail at the other end
110
What is the process of riveting?
1 The two pieces to be joined are overlapped and drilled.
2 The rivet shaft is inserted into the hole.
3 The head of the rivet is dome-shaped and a 'set' tool is placed over this (also known as a snap)
4 The end of the shaft is hammered over to squeeze the two pieces together.
111
What is the process of pop riveting?
1 The rivet used in pop riveting has a rivet and a pin.
2 The rivet head is pushed through a hole drilled through the two pieces of metal being joined
3 Riveting pliers grip and pull the pin, and as this happens, the head of the rivet squashes and pulls the two pieces of metal together.
4 The pin breaks off and is disposed of
112
What are the 3 temporary fasteners?
1 self-tapping screws
2 machine screws
3 nut and bolt
113
What are self-tapping screws used for?
joining thin sheet metal
114
How do you use a self-tapping screw?
1 A pilot hole is drilled through the metal parts to be joined.
2 The screw has a coarse thread which is made from hardened steel.
3 When it is screwed into the pilot hole, it cuts its own thread, which holds the screw in place.
115
Where are self-tapping screws used?
electronic children's toys where battery compartments must be secured with a screw for safety
116
When are machine screws used?
join thicker pieces of metal together including machine parts such as inspection covers on motor or gear housing, or parts that need to be removed for maintenance
117
How do you use a machine screw?
They have a thread the entire length of the shaft. Where there are two pieces to be joined, the top piece will have a clearance hole larger than the thread on the bolt. The bolt goes through this, and is then screwed into a threaded hole in the second piece.
118
How are machine screws tightened?
with a spanner or allen key
119
What are washers?
They might be put under the head of the bolt and under the nut, in order to spread the tightening force over the surface of the material and to stop the bolt head and nut from digging into the surface
120
What are spring washers used for?
They may be used to keep the tension on the joint, to prevent it from coming undone if the item may be subject to movement to vibration
121
What type of metals are bolts made of?
alloy steels, nylon, brass and aluminium
122
How do nylon nuts work?
They have a nylon collar insert at the end of the nut. As the nut is tightened over the bolt, the nylon elastically deforms over the bolt thread. The nylon insert helps to stop the nut coming undone through vibration, so they are often used on machines or equipment that are subject to movement.
123
What are the 6 metal wasting processes?
1 milling
2 turning
3 flame cutting
4 plasma cutting
5 laser cutting
6 punching/stamping
124
What does milling do?
Depending upon the type of cutter used, milling can be used to cut slots, to shape the edge or the surface of the work piece or to drill and even thread holes
125
What is turning?
It is a process carried out on a centre lathe. Work such as a bar can be held in a rotating chuck and machines to reduce the diameter, and to square off or 'face off' the end, thread and drill.
126
What is flame cutting?
It is a wasting process that uses oxy-acetylene gas and a special flame-cutting torch to deliver a very intense and focused flame above 3500 degrees Celsius. It is used to cut low carbon and alloy steel plate.
127
What is the process of flame-cutting?
1 The metal is heated and a melt pool begins to form.
2 At this point, an additional jet of oxygen is introduced.
3 This intensifies the flame and pierces the metal, forcing a jet of melted metal and carbon (known as slag) with it.
4 The flame is then moved along the cutting path to continue the cut.
128
What is the advantage of flame-cutting?
It is an economical process to set up because the equipment is readily available.
It can be carried out in almost any location because electricity is not required.
129
What is the disadvantage of flame-cutting?
It is difficult to maintain a parallel line with high levels of tolerance.
There may also be deformation, structural changes and tempering on the cut edge.
130
How does plasma cutting work?
Plasma is a super-heated ionised gas that is electrically conductive. A plasma cutter will use this conductive gas to transfer the energy from the power supply to a conductive material such as a steel plate. The resulting cut is faster and cleaner than using oxy-acetylene.
The plasma arc is directed out of a torch where a gas such as oxygen, nitrogen, argon or compressed air is forced through a tiny nozzle. An electric gas is generated from a transformer and, combined with the gas, forms a jet of plasma. The heat generated by the plasma can be as high as 28000 degrees Celsius, which quickly burns through the material and blows it way.
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What type of production does plasma cutting use?
one-off
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What is a typical set-up of a plasma cutter system?
1 a power supply which converts AC mains to DC - this is usually varied between 200 VDC to 400 VDC depending upon the material thickness being cut.
2 An arc starting console - this provides a spark inside the torch to start the plasma arc.
3 A plasma torch - this contains an electrode and nozzle which are consumable parts. The torch can be used manually or controlled by CNC systems for accuracy and repeatability.
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How does a laser cutter work?
It uses the power from a high-powered laser that is directed through optics. The laser melts the material and a high-pressure has or compressed air blows the melted material through the sheet.
The laser beam is emitted from a 'laser tube' where it is reflected through a series of mirrors in a similar way to a periscope into a 'laser head'. The head contains a lens which focuses the laser into a fine beam for cutting and engraving. Laser beams usually have a very fine tolerance, and the amount of material removed in the cutting process can be less than 1mm.
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What is punching?
It is a wastage process that uses computer controlled machines which stamp out sections of sheet material using hardened punches following a CNC program.
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What is the process of punching?
1 uses the shearing action on a sheet of metal placed between an upper tool (punch) and a lower tool (die).
2 The punch pushes through the sheet material, producing a punching slug that drops through a hole in the die.
3 The pieces are collected via a chute for further work or recycling if the punched sheet is the desired part.
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What are the 8 wood joints?
1 butt
2 mitre
3 comb
4 dovetail
5 mortise and tenon
6 housing
7 half lap
8 dowel
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When is a butt joint used?
very lightweight applications such as modelling
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How is a dowel joint made?
1 measuring and marking the position for the dowels
2 drill holes for dowels
3 put wood glue in holes
4 hammer dowels into position to them clamp the two pieces together
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Where are dowel joints used?
flat-pack furniture such as a bookcase or wardrobe
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How do you make a mitre joint?
1 cut each corner to 45 degrees
2 glue and clamp them together
3 use a jig to keep the corners straight
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Where are mitre joints used?
picture frames
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Where is a comb joint used?
to make boxes
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What is an advantage of the comb joint?
The combs create an increased gluing surface area, which makes a very strong joint
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Where are dovetail joints used?
making drawers
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What is the advantage of a dovetail joint?
They have directional strength. Once glued together, they are impossible to pull apart so they are excellent for joining the front and back of a drawer to the sides
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What are mortise and tenon joints used for?
heavy-duty constructions for furniture or similar applications
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How do you make a mortise and tenon joint?
1 Make a square or rectangular hole - known as a mortise - in one of the parts to be joined.
2 cut a tenon
3 Spread PVA glue into the mortise and clamp the two parts together
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What are housing joints used for?
framework construction, cabinet and shelving
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What are half lap joints used for?
simple frames or boxes
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What are the advantages of using knock-down fittings for manufacturers?
KD fittings are used to manufacture flat-pack furniture. They enable manufacturers to supply products that not assembled, therefore reducing the cost for both the manufacturer and customer. This reduces the making time, and makes it easier to store the products and transport them.
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What are modesty blocks?
They are small, rigid, polymer blocks. They have moulded holes that take screws which are used to join the blocks to panels.
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Where would modesty blocks be used?
cupboards and storage units
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What are the disadvantages of using a modesty block?
It does not make a particularly strong joint and it is unattractive, so it is becoming outdated in mainstream furniture manufacture.
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What are the 3 types of KD fittings?
1 modesty block
2 barrel nut and bolt
3 cam-lock connector
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How do you work a barrel nut and bolt?
This uses a cross dowel that is fitted into one of the pieces to be joined. The bolt is inserted through the other piece of timber and tightened into the cross dowel.
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Where are barrel nut and bolt fittings used?
used to assemble parts of flat-pack furniture such as the frame of a bed or table
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How do you work a cam-lock connector?
Cam-lock connectors consist of a metal dowel that is screwed into one of the pieces by inserting a screwdriver into the slot on the side. The cam is a disk that fits into a pre-drilled hole in the other piece. When the disk is rotated with a screwdriver, the collar on the dowel locks into the cam and pulls both pieces tightly together.
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Where are cam-lock connectors used?
flat-pack furniture such as bookcases, where the horizontal shelves are attached to the sides
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How do wood screws differ to screws used for sheet metal?
Wood screws have a coarser pitch (fewer threads per inch)
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What is the advantage of a wood screw having a coutersink?
This allows the screw to fit flush with the surface of the wood, providing a countersunk hole is drilled.
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What are the 3 different forms that screws come in?
1 slot head
2 phillips
3 pozidriv
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What do bolts do?
Bolts that are used to join pieces of wood together - called 'coach bolts' - have a thread that runs about two-thirds of the way along the bolt. Under the domed head of the bolt is a square piece that digs into the wood when tightened, preventing the bolt from rotating. This means that when the bolt is tightened, the domed head cannot be undone with a spanner. This is useful in fitting bolts or locks to wooden doors because it makes them secure if the domed part is on the outside.
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What are the 3 wooden wasting processes?
1 turning
2 routing timber
3 milling timber
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What are the 3 methods of turning wood?
1 turning between centres
2 turning on a faceplate
3 turning in a chuck
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What is turning between centres when turning wood?
It is used to machine a spindle such as chair legs and table legs. It enables the spindle to be machines to a reduced diameter.
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What is turning on a faceplate when turning wood?
It is used to machine items such as domes or bowls. This involves screwing a thick piece of timber to a faceplate, where it can be machines to turn the outside circumference and to remove the inside in order the make a bowl.
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What is turning in a chuck when turning wood?
To grip the item while it is machines. Can be used to machine the sides and inside of wooden bowls and vases. The rim of the base of a bowl or vases would be gripped by the jaws of the chuck, allowing access to the sides and inside for machining.
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What does routing timber mean?
Routers can be used to machine timber in order to make slots and holes, or to make decorative 'mouldings' on the edges
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Why are milling machines not used for accurate jobs?
Milling machines run too slow a sped for machining timber accurately, however they can be used for small sized, basic jobs such as rough prototypes or roughing out a small hole or channel.
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What are the 2 forming processes for timber?
1 lamination
2 steam bending
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How do you laminate timber?
Wood veneers or thin manufactured boards such as 3mm plywood can be glued together and bent over a former, so that when dry, they form a thicker board in the shape of the former. While drying, the laminates may be held in place with clamps.
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How do you laminate timber using vacuum bagging?
With vacuum bagging, the former and veneers are placed under a polythene sheet. The edges of the sheet are taped down to the table. A valve is fitted to the polymer sheet and a vacuum pump sucks out the air, and the resulting pressure pulls the laminates hard together. This ensures that there are no gaps in the laminating.
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How does steam bending wood work?
The process involves putting timber into a steam box where the timber will absorb the steam. The timber is then bent over a former and clamped to it until it dries.
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What are the advantages of using steam bending over lamination?
It is quicker than waiting for glued layers to dry.
It is less wasteful because laminated parts usually require trimming to final size.
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What are the 7 types of adhesive and fixings used to stick materials together?
1 polyvinyl acetate (PVA)
2 contact adhesives
3 UV hardening adhesives
4 solvent cement
5 jigs and fixtures
6 sanding jigs
7 router jigs
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What does PVA stand for?
polyvinyl acetate
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How is PVA used to stick materials together?
It is used to bond woods and wood-based materials together. PVA soaks into the surface of the wood and sets once the wood has absorbed the water content.
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What is contact adhesives used for?
large areas such as sheet material
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How do you use contact adhesive?
The two surfaces to be joined are coated in contact adhesive and left for about 10 minutes, or until the adhesive feels tacky. On contact with the other surface, adhesion is instant, which means clamping is not required.
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How do UV hardening adhesives work?
UV hardening adhesive is a clear liquid which 'cures' to form a bond when exposed to UV light. UV hardening adhesive contains a photo initiator, which means that it absorbs the UV light wavelength, it begins to cure and set to a solid bond.
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What is the advantage of using UV hardening adhesive?
Any excess adhesive can be wiped away prior to being exposed to UV light, this giving a solid and clean joint.
It has a fast curing time
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How does solvent cement work?
Softening the surface of the polymers to be joined, allowing them to fuse together.
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What is a fixture?
Something that holds work in a given position while a manufacturing process takes place.
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What is a jig?
It holds the work and guides a tool
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What are sanding jigs used for?
They are used to hold and guide timber as it is sanded on disk or belt sanders. Typically, the angles on the end or edges of timber are sanded, and using a jig means that the angle will always be accurate and consistent.
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What are router jigs used for?
Jigs can be used in conjunction with routers to shape wood accurately and consistently. Typically, a jig might be used to angle the router in a fixed position, while the edge of a piece of timber is run against the router bit.
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What is a circle-cutter jig with regard to router jigs?
It is used to make circles in timber or manufactured boards. These work like a beam compass or trammel, where the router is fixed to a long piece of timber which is adjustable, to allow for cutting piece of different diameters.
