Engineering Summary PDF

Engineering Summary Smelting Metals Impure Metals (Ores) need to be tested before application – This could be for different properties, appearances etc Refining Crude Oil Fracti...

Engineering Summary Smelting Metals Impure Metals (Ores) need to be tested before application – This could be for different properties, appearances etc Refining Crude Oil Fractional Distillation occurs when crude oil is heated in the crude oil distillation Cracking – the breaking down large hydrocarbon molecules found in separated fuel types Metals Alloys Brass: Alloy of Copper + Zinc – Sonorous, Used in locks, gears, door handles etc Bronze: Alloy of Copper - Higher melting point than brass, highly ductile, generally 10% more dense than stainless steel – Used in sculptures and bearings Duralumin: Alloy of Aluminium - Lightweight, Hard – Used in air craft Bauxite: Alloy of Aluminium – Low Conductivity, hard and abrasive – Needs to be refined and then smelted using electrolysis Ferrous Mild Steel: Tough, Ductile, Malleable, Poor Corrosion Resistance – Used in general construction and cutting tools High Carbon Steel: Resistant to wear, Brittle, Poor Corrosion Resistance – Used in hand/machine cutting tools Stainless Steel: Can be made magnetic, ductile, corrosion resistant – Used in Cutlery, Surgical instruments etc Cast Iron: Very heavy, rigid, easily machined – Used in old lamp posts and art pieces Non-Ferrous Aluminium: Soft, low strength, high conductivity, can be alloyed with easily – used in many metal products Zinc: Corrosion Resistant – Used to galvanise other metals Tin: Corrosion Resistant – Used to make Tins Copper: Pure form is soft, Malleable, Corrosion Resistant, Thermally and Electrically Conductive – Wires and electrical applications, etc Tungsten: Toughest material, super dense, resistant to corrosion, melting point of 3422°C – Drill Bits and tools Woods Manufactured Boards Made of recycled woods, Available in large sheets, Properties are consistent, Available pre-finished. ❖ Engineered Boards: (Including Cement Bonded particle Board) ❖ Laminated (Including Plywood): Plywood is strong and cannot split, Marine Plywood is water resistant and thinner than regular plywood, flexi plywood is more flexible than regular plywood ❖ Compressed (Including MDF):Bonded with Resin, same as plywood, just larger chunks ❖ Wood Veneers: Stuck on manufactured boards to improve aesthetics Hard Woods Hard wood trees are slow growing and need more land than deciduous trees, therefore they are more expensive, they are favoured for aesthetics. ❖ Oak: Resistant to Rot, Long Lasting, Strong, Durable, Corrodes Steel – Used in construction, furniture and ship building among other things ❖ Ash: Springy and quite elastic, shock resistant – Used mostly in sports equipment and tool handles ❖ Birch: Uniform, even texture, low cost , least resilient hardwood against insects, rot resistant – Used in veneers, plywood, furniture, cabinets etc ❖ Mahogany: Endangered species, aesthetically pleasing, stable, highly prized – Used in vintage furniture ❖ Beech: Flexible, tough, odourless, resistant to abrasion, very hard to chip – Used in bowls and toys ❖ Teak: Naturally high in oils, high resistance to acids and alkalis – Used mostly in outdoor furniture and chairs Soft Woods Fast growth means mostly low cost, mostly lightweight means less seasoning ❖ Douglas Fir: Tough, cheap, strong, hard to treat – Used in construction ❖ Red Wood: Grow quickly, great strength to weight ratio – Used in construction, decking and instruments ❖ Spruce: Great Strength to weight ratio – Used in aircraft during WW1 and 2 ❖ Cedar: High Oil content, resistant to decay and insect attack, hard to add a finish, fairy toxic – Used in outdoor furniture, fencing, decking etc ❖ Larch: High resin content, - Used in veneers, fence posts, furniture and boats Woods Random stuff to be memorised ❖ Rough Sawn Timber (Cheapest) – Used Most in construction, Used outdoors ❖ Planed Timber – Made using a planer and thicknesser, smaller and more expensive then rough sawn Never Plane against ❖ Natural Timbers – Most Wood sold as boards and square sections as rough sawn or PSE or PAR the grain ❖ PSE Timber – has one square edge ❖ PAR Timber – square on all sides ❖ Wood Grain – The Structure of wood grain can affect workability and cost ❖ Wood Structure – Wood is like a group of straws ❖ Anisotropic – A material that Is easy to break in one direction and hard to break in another ❖ Seasoning – Taking Timber and removing all of the water, this can be done outside (taking over a year) or in a kiln (taking a day), it increases stability, strength and resistance to decay ❖ Distortions – Wood is hydroscopic (absorbs moisture and swells in damp conditions), as water evaporates, wood shrinks ❖ Joining wood – Adhesives, Joints and fittings ❖ Forming – Adding/removing material, bending (steaming) ❖ Laminating – Can create curves, can be used to join materials, can increase the materials qualities ❖ Tanalising – Prevents insect attack, pressure cooker forces copper into a wood Ceramics ❖ Used in aerospace, electronics and biomedical fields. Made from the same ingredients every time. Have superior properties than unrefined ceramics Borosilicate Glass – Low coefficient of thermal expansion Silicon Carbide – Can be combined with steel, can tolerate high temperatures, incredibly hard and hard wearing Tungsten Carbide – High Melting point, twice as stiff and dense as steel, very high hardness Polymers Thermosetting ❖ Cannot be reused and has strongly linked monomers. Often Hard and Durable. Made from Crude Oil. Urea Formaldehyde – Hard, inexpensive and brittle – Used as wood glue Epoxy Resin – High Strength content, stiff, brittle, chemical resistance, electrical resistance, temperature resistance – Used coatings, LED’s, high tension electrical components, manufacture of paint brushes Phenol Formaldehyde – High working temperature – Used as laminate sheets and coatings on metals Polyester Resin – Often bonded with other materials, lower cost than other resins – Used in industrial coatings and boat building/repair Thermoplastic/Thermoforming ❖ Can be reused and have loosely linked monomers. Recyclable, remoudlable. Made from Crude Oil. Polyethylene (PE) – 120–130-degree melting point, flexible, translucent, weatherproof, tough, easy to process, low cost – Used in food containers, bottles, toys Polyamide (PA) – 220–260-degree melting point, high wear resistance, high thermal stability, good strength and hardness – Used in textiles, sportswear, automotive parts and utensils ABS – Good Resistance against medium temperatures, Hard, Tough, antistatic, good resistance, can be painted – Used in Gardening tools, medical applications, pipes and fittings and automotive parts Polypropylene (PP) – Poor UV resistance, Translucent, Rigid, very light, excellent chemical resistance, microwavable – Used in plastic packaging, plastic parts for machinery and equipment, carpeting and ropes PVC – Good UV resistance, excellent chemical resistance, glue able, weldable, bendable, machinable and stiff – Used in medical tubing, window frames, fencing and decking and shrink wrap PET- Very light, high tensile strength, hard, stiff and used in drinks bottles – Used in bottles, containers and chemical storage Acrylic – Weather resistant, difficult to recycle, corrosion resistant, electrical insulator – Used in lenses, replacements for glass, fashion accessories, display products and indoor/outdoor signs Polymers Thermosetting UF – Hard, opaque, - used in adhesives, electrical casings, sockets and switches MF – Hard, scratch resistant, opaque – surface coatings, decorative coverings etc PR – Most common form of resin used in the marine industry – Plastic boat hulls, bath tubs, chair seats Epoxy Resin – Clear Resin that also needs to be mixed with a catalyst to cure – used as an adhesive, surface coating and encapsulating LED’s Thermoplastic/Thermoforming LDPE – is derived from Ethylene, quite flexible but also tough – used in food containers HDPE – tough, high strength to weight ratio – used in containers for chemicals PP – tough, flexible, fatigue resistance – used in food packaging, medical equipment HIPS – Rigid, lightweight high impact – used in yoghurt, cutlery, salad bowls ABS – Hard and tough, excellent impact strength – used in computer cases, hard hats, car bumpers, wing mirror PMMA – tough, lightweight – alternative to glass, used in shower trays, baths, car lamp covers, lenses Nylon – Used for mechanical components like screws and gears, woven textiles, tents and seat belts, carpets Rigid PVC – Can be rigid, flexible – used in plumbing, guttering and drain pipes Flexible PVC – Plasticiser added to PVC to increase flexibility – used in hose pips, electrical insulation, inflatable products, clothing and upholstry Modern Materials E-Textiles – Materials that eliminate the need for wires and hard electronics – Used in sensors, thermochromic displays, communication, data, heating and medication Super Alloys – Used in extreme applications – Used in turbine engines, marine applications, nuclear plants, oil and gas industries High Performance Alloys – Unique alloys that are made to meet specific performance needs – Used in a wide variety of industries Bioplastics – Plastics made from natural sources – Fossil Fuels, corn, cane, sugar and potatoes Nanocrystalline – Extremely small materials with crystalline properties, they are hard and wear resistant – Used in cutting tools, tungsten and carbide Nanocomposites – Materials added to improve one particular property to another material – Used in a wide variety of industries Smart Materials ❖ Respond to external factors (e.g. heat change, change in electrical charge, change in pressure, etc) Thermochromic – Respond to changes in temperature (Change in colour) Phosphorescent – Respond to changes in light (Change in light output) Photochromic – Respond to changes in light (Change in colour) Electrochromic – Respond to changes in current (Change in colour) Piezochromic – Respond to changes in pressure (Change in colour) Solvatochromic – Respond to changes when dissolved (Change in colour) Shape Memory Alloys – Deformed when cold but changes to its pre-deformed state when heated Shape Memory Polymers – Deform when the shape is heated or pressure is applied Properties Property/Characteristic Meaning Compressive Strength The ability to withstand being crushed or shortened by pushing forces Tensile Strength The ability to resist forces that stretching or pulling forces Stiffness The ability to resist forces that may bend the material Hardness The ability to withstand wear and abrasion Durability The ability to withstand weathering and damage Impact Resistance The ability to absorb impact force without fracture Plasticity The ability to be permanently deformed and retain that shape Elasticity The ability to be deformed and then return to the original shape when the force is removed Malleability The ability to withstand deformation Ductility The ability to be drawn into wires Properties Ductility The ability to be drawn into wires Density The mass of the material in a standard volume of space Strength to weight Ratio Comparing the weight of the structure to the amount of weight it can support without fracture Flammability How a material burns once ignited and the degree of difficulty required to cause combustion Electrical Conductivity Whether the material is an electrical conductor. An electrical insulator does not allow a current to pass through the material Thermal Conductivity A thermal conductor allows heat to transfer heat through itself. A Thermal insulator does not allow heat to pass through it. Corrosion/degradation resistance The ability of the material to withstand environmental attack and decay Additives - Enhance the Polymers properties - (EG) Fire Retardant, Antistatic, Biodegradability etc Material and Component Considerations Materials need to have been tested, be profitable, fit for the purpose and have desirable characteristics/properties Aesthetics Reducing Costs Environmental Considerations Feel/Touch Higher fuel efficiency Social (Area/political, etc.) Colour Specialist vs Compatible materials Ethical (Animal Testing etc.) Texture Storage and Handling Economic (Money) Shape Standard component parts Environmental (CO2, etc.) Longevity Development of materials/processes Form Availability of Source End User Selection Mechanisms Efficient Mechanisms transfer power without adding or subtracting from it. Efficiency = Actual Mechanical Efficiency/Ideal Mechanical Advantagex100 = % Efficiency = Output Power/Input Power x100 = % (Input Force x Input Speed) = (Output force x Output Speed) If energy is lost, the output force will be less than the above principle suggests Actual Mechanical Advantage = Measured Output Force/Input Force Mechanisms Mechanical Advantage =Load/Effort Motion Rotary Linear Reciprocating Occilating Mechanical Advantage Load/Effort = Mechanical Advantage Epicyclic Gears Used in cars, engines, gear boxes, drills and motors 3 gear ratios Gears Idler Gear Mitre Chain and Sprocket Belt and Pulley Worm Drive Screw Thread Rack and Pinion Bearings and Lubrication Bearings are components that support moving parts Planned Bearing – Ball Bearing – Tapered Bearing Fluid bearing – Longer Lasting, low friction, almost no wear Thrust Bearing Drive Shaft – Requires two points of contact Axial Loading – Force along an axis Radial Loads – Act at right angles to the shaft Systems Systems can Generate/Control/Change motion Force is often called effort Output force is often called load Mechanical Advantage = Distance moved by effort/Distance moved by load Mechanical Advantage =Input arm length/Output arm length Linkages Bell Crank Crank and Slider Peg + Slot Processes Joining Woods – Adhesives: Difficult with high oil woods - Joints - Fittings Framing –Adding/removing material Laminating – Can create curves, can join materials, can increase surface area Tanalising – Prevents insect attack, pressure washer forces copper sulphate into a wood Definitions I didn’t know CADD – Computer aided design and drafting (designs get converted into technical drawings)