Manufacturing Flashcards

Question

Drilling

Answer 1

* Low Cost * Efficient * Poor heat removal * Poor accuracy/finish * Swarf removal difficult on deep holes - Depth > 5x diameter

Answer 2

Produces special shaped holes, slots and external surfaces * Fast, low cost operation * Successive teeth remove material * Machining completed in one pass 8 * Pull and push variants available * Very high tool cost * Excellent repeatability

Answer 3

* Operation: Manual, lathe, drill press/tapping head * External threads cut using: - Circular split dies, solid nut dies - Coventry die head for capstan use

Answer 4

Advantages: * Final shape produced in a single step * Complex shapes possible * Low component cost Disadvantages: * Poor surface finish * Poor dimensional accuracy * Low component strength * High setup and energy cost

Answer 5

Pattern required: * Duplicate shape of part * Can be made from: - Wood: low quality - Plastic: e.g. produced by 3D printing - Metal: expensive, robust * Draft required to allow removal from mould Must consider shrinkage, finishing operations and distortion * Typical shrinkage: - Cast iron: 1% - Steel: 2-2.5% - Al, Mg: 1-1.3% - Brass: 1.5%

Answer 6

Cope and Drag: Top and bottom halves of mould Riser: Liquid metal reservoir Cores: For hollow sections Core print: Supports core

Answer 7

Traditional casting process * Numerous materials, design flexibility, low cost process, low volume production possible * Poor finish, accuracy, component strength

Answer 8

* Hot metal pattern dipped into fine sand mixed with resin to form thin shell * Mould split and baked, placed in pouring jacket * Good tolerance, surface finish and productivity * High labour / process cost

Answer 9

* Vacuum used to maintain the mould shape during casting – no binder required in sand * Sand immediately reusable after demoulding, little / no fumes * Slow process – normally used in prototypes

Answer 10

* Moulds made from sand, clay and water using permanent patterns - water frozen for rigidity * Castings have good finish * Sand immediately reusable * Not commercially available

Answer 11

AKA: Evaporative Casting, Lost Foam, Expanded polystyrene * Polystyrene foam pattern, ceramic coated and loose sand packed - pattern decomposes during pouring * No parting line, one-offs possible, poor surface finish

Answer 12

* Similar to shell moulding but with a “rubbery” mould * Greater variety of shapes possible – flexible mould allows slight undercuts * Expensive, possible parting line

Answer 13

* Reusable rubber mould * Only suitable for casting low melting point materials, e.g. wax, plastic, “Wood’s metal”

Answer 14

Uses metallic die (mould) - preheated * Reusable mould * Good finish, tolerance, High productivity, Controlled cooling * Limited mould life, high tooling costs

Answer 15

Hardened tool steel dies, metal cores * High pressure applied during solidification * High process speed, high complexity and detail possible, low porosity * Very high tooling and equipment costs

Answer 16

* Pour molten metal in the mould, "slosh about”, cooling the outside shell - pour out when thin shell is formed * Poor quality – limited to “decorative” items

Answer 17

Use centrifugal force for casting hollow parts * Consistent wall thickness, dense, high quality structure * Limited to cylindrical geometries

Answer 18

* Use centrifugal force to apply pressure * Produces dense/homogeneous castings * Used for small, high quality parts (e.g. jewellery, dental implants)

Answer 19

Partially solid metal is squeezed in a die * Pressure maintained until full solidification * Homogeneous components, similar properties to forging * Little commercial use

Answer 20

* Used in heavy industry (e.g. steel works) * Surface solidifies in mould, bulk solidifies as material passes along rollers * Impurities remain in “Tundish”

Answer 21

Finishing: * Cleaning * Machining * Defect repair * Heat treatment * Inspection Design Considerations: * Parting line location * Avoid sharp corners or edges * Uniform thickness / gradual thickness change

Answer 22

* Engineering systems are complex * Individual parts are easier to manufacture * Products can be disassembled for maintenance * Allows use of different materials * Promotes mass production and reduces cost

Answer 23

Can be temporary (e.g. nut and bolt) or permanent (e.g. rivets, crimps)

Answer 24

Deformation in hot working condition * Oxide and contaminants are squeezed out * Develop inter-atomic bonding

Answer 25

* Localized pressure, large amount of cold work * Vacuum required * Used for small parts

Answer 26

* Rotational friction and pressure * Welded throughout joint - strength almost the same as the base material * Typically used for drive shafts

Answer 27

* Ultrasonic vibration and pressure applied * Restricted to thin, small, parts, e.g. electronic components, plastic components

Answer 28

* Flat and highly polished surfaces held together under pressure and heated in inert atmosphere * Limited deformation, high bond strength * Slow process - 15 minutes to several days * Good for welding Ti-based super-alloys (e.g. aircraft components)

Answer 29

* Induction coil used to induce eddy currents * Creates localized heat at joint faces – small HAZ * Pressure applied to forge the joint * Highly conductive material can be easily joined

Answer 30

* Temperature and pressure produced by explosion * Produces bond not easily achieved by other means - large areas bonded very quickly * Can weld metals with different melting points * A way of cladding materials to increase corrosion resistance

Answer 31

* Heat from burning Acetylene (C2H2) and Oxygen * Usually uses filler * Oxide contamination leads to poor weld quality * Heat is not concentrated, slow, large HAZ

Answer 32

* Electric arc provides heat, gas required (from flux) to stabilise arc and protect weld * Shielded metal arc welding – “MMA”: coating creates gas shield, alloying elements (slag must be removed) * Electrode is consumed

Answer 33

* Flux inside electrode: * Good control of welding parameters * Thinner electrode size needed

Answer 34

Granular flux gives excellent shielding: high quality weld * Filler wire fed from reel * High speed and deep weld penetration

Answer 35

* MIG (Metal Inert Gas) or MAG (Metal Active Gas) * Uses Argon, Helium, CO2, or mixture of shielding gases, fed through nozzle * Consumable wire reel electrode: easy to automat * No/very little slag to remove

Answer 36

* Non consumable electrode, constant arc * Separate filler rod used, inert gas supplied as shield * High quality weld, deep penetration * Skilled manual operation: slow speed, high cost

Answer 37

* High gas temperature due to ionization by arc: temperature up to 20,000°C * High energy concentration: localized heating * Fast, deep penetration, narrow HAZ * Temperature can be controlled through gas selected

Answer 38

Weld formed through heat from electrical resistance and pressure – no filler used * High reliability, small HAZ, low distortion, simple automation, can weld plated metals * Discontinuous weld, limited to lap joints

Answer 39

* Projections pre-pressed into components - multiple simultaneous welds possible, precise weld location * Lower contact resistance for same force * Less wear on electrodes than resistance welding

Answer 40

Heat produced by exothermic reaction, e.g. “burning” aluminium and iron oxide: 8Al + 3Fe3O4 → 9Fe + 4Al2O3 * Typical uses: rails/large castings, cutting scrap metal

Answer 41

Joins thick plates in single pass - whole face welded * Consumable electrodes act as filler - vertical feed * Used for large bridge sections, boiler shells, etc.

Answer 42

* Single pass welding of thick material, precise welding of small components - high precision, low heat input * Very high equipment costs * Cutting holes with length/diameter ratios up to 25:1

Answer 43

* Fusing/repairing plastics - filler rod often used * Reflowing solder during circuit board fabrication

Answer 44

Distortion in joints: * Care needed to minimise deformation in joint design Challenges in liquid state welding: * Material composition changes * Cavities, contamination * Residual stresses * Most failures start at the HAZ * Must consider cost of multi-run welds and joint preparation

Answer 45

Forming involves plastic flow in the solid state. Advantages: * Fast production * Efficient material usage * High strength components, due to Work hardening, grain refinement and defect closure * Better surface finish and tolerance than casting Disadvantages: * High force requirements - specialist equipment * Tooling can be expensive * Inferior surface finish and tolerance to machining * Friction consumes ~50% energy input and causes die wear * Anisotropy can be a problem

Answer 46

* Involves hammering at high temperature * Oldest method * Low quantity production

Answer 47

* Heated metal formed to shape between two shaped dies – hammering used in drop forging * Excess metal used: flashing * Machining allowance needed for finishing

Answer 48

* Slow, uniform deformation * Improved dimensional accuracy and fewer intermediate steps (than drop forging) * Cooling dies often required due to longer contact

Answer 49

* Material gripped so that requisite length projects, upset area is heated * Forging performed by moving die/punch * Typical use – bolts, headed components

Answer 50

* Used for long lengths of uniform cross section * Friction drives the material between rollers * Typically used for flat rolling, shape rolling, roll forming of pipes (e.g. seamless pipes on Mannesmann mill)

Answer 51

* Threads can be hot or cold rolled * Material grain structure follows thread

Answer 52

* Usually follows a hot rolling operation * Pickling used to remove scale * Good surface finish, thickness control and workhardening (often desirable)

Answer 53

* Material pushed through shaped die (hot or cold) * Can produce complex geometries with constant cross section * Normally used with non-ferrous alloys

Answer 54

Material pulled through shaped die * Good surface finish and accuracy, work hardening often desirable, lubrication is crucial * Typical max. reduction in area is about 20% per pass