design for manufacture

what is hardwood (type of tree) and what types of trees are they? examples (7)?

• they are trees with leaves

• they are slow growing

• deciduous

• ash

• basswood

• beech

• birch

• maple

• oak

• walnut

what is softwood? what type of tree are they? examples (4)?

• needle bearing

• fastgrowing

• coniferous

• cedar

• spruce

• fir

• pine

what are exit woods? ex(6)?

• woods from South America, Africa, and Asia

• teak

• purpleheart

• mahogany

• sapele

• padauk

• zebrawood

what types of grain are there on a piece of wood?

• face grain (top (3.5))

• edge grain (side (1.5))

• end grain end of wood

wood vs timber?

• wood - natural fibres that make up a tree

• timber - trees or logs that are ready for or being used in construction

what are these imperfections called?

what are the properties of wood? (4) how are they measured?

• weight - a function of the density of wood - slow growing tree is usually higher in density (hardwood)

• strength and stiffness - strength is measures by how much force it can withstand in wither tension or compression

• hardness - measured in terms of how rich resistance the wood has to indentation or scratching - uses the Janka test (measures the amount of force required to embed a 0.444” steel ball into the wood to half of its diameter)

• rot resistance - all wood will eventually rot, some will rot after though

what are some applications of wood? (9)

• construction

• fenestration

• flooring

• toys

• lighting

• furniture

• house wears

• marine

• musical instruments

what does hygroscopic mean? what are two ways of drying wood?

• a substance can easily attract and hold water molecules from its surrounding environment

• air drying - outside, takes longer, family owned business

• kill drying - inside, uses heated air, mass manufacture

how much moisture does Greenwood, wood for outdoor use, and wood for indoor use have?

• Greenwood - 28% moisture

• wood for outdoors - 12-14% moisture

• wood for indoors - 6-8% moisture

how is wood sold? (shapes) (5)

• boards

• plywood

• particleboard

• dowel

• veneer

what is plywood? what are different grades of plywood (what do they mean)?

• at least three sheets of peed off wood from the log laminated in different directions

• a, b, c, etc

• grade a - sanded Bothe sides, useful for cabinetry and finer work

• grade b - a smooth, sanded surface with minor, neatly repaired defects like small sound knots or wood patches up to one inch across

• grade c - rough and mostly used in construction

what is particle board ? where is it used?

• a way that wood is sold made from woodchips and glue

• used in kitchen cabinet construction - IKEA products

what to veneer laminates do? how are they sold ?

• provide real wood finishes - applied to the top of plywood or particle board

• can come in edging for laminates, sold in rolls or strips

why is bamboo good? (3) where is it grown?

• its fast growing

• harvest - you don’t need to replant

• consumes less water

• southern hemisphere

what are types if joints (joining wood) (7)

• butt joint - simple, not string, looks bad

• mitre joint - join together at an angle (most picture frames)

• mitre joint with splines - mitre joint with insterts to keep it together better

• biscuit joint - create a circular, flat biscuit shape, cut half of the diameter into two separate pieces of wood, put the biscuit in each side & push them tog.

• mortise & tenon - create a hole in one piece, a Male end in the other piece the size of the hole and put them tog - very strong & load bearing

• dovetail joint - very strong, decorative - can be done with a router and a gig

• box joint - strong - can be done with a router and a gig

what are different types of glue (4)? - what is glueing only as good as?

• wood glue - indoor and outdoor

• epoxy - very string

• cyanoacrylate - crazy glue (need a smooth surface)

• polyurethane - foam (expands)

• glueing is only as good as your clamping and surface accuracy

what is cork? where does it come form?

• the tick outer bark (periderm) of the cork oak tree

• protugal/mediteranian region

what is fabrication? (4) + (ex)

• usually used for hands-on, custom, smaller projects

• focuses on building individual parts and framework structures used in larger systems

• making or building something from raw material

• a trailer frame, that is wlded from rolled form aluminum extrusions

• low volume production

what is manufacturing? (4) +ex

• process of turning raw materials into finished goods on a large scale using tools, human labour, machinery, and chemical processing

• entire product lifecycle

• produces finished goods (cars, electronics)

• automated assembly lines and repetitive high-volume output

• high volume production

what are three suppliers in Ottawa and what stores sell different metal shapes? (4 + $ fact)

• loucon metals

• metals pros

• metal supermarket

• hardware stores

• home depot

• princess auto

• Canadian tire

• (getting metal from hardware store is usually more expensive)

steel vs aluminum

• Steel

  • dull inside corners due to bending

  • heavier

  • conductive

  • changes colour when hot

  • rough surface

• Aluminum

  • sharp corners due to going through a die

  • soft & light

  • does not change colour when hot

  • needs to age to harden

  • smooth surface

hot rolled vs cold rolled steel (7)3 diff

• hot rolled

  • metal is heated up and rolled into sheet/shape

  • it cools at room tempurature

  • it deforms slightly after its rolled so its not suitable for precise projects

  • it can make bigger things than cold rolling

  • rough surface - cheaper

  • I beams, train tracks, construction frames

  • round edges

• Cold rolled

  • hot rolled, colds at room temp, rolled again, turned, righted, and polished

  • stronger and more precise

  • sheet metal

  • smooth surface, pricy

  • household appliance, furniture, car body panels

  • defined edges

3 different ways to cut metal

• sawing

  • hacksaw (not great accuracy)

  • vertical bandsaw (used for smaller pieces

  • horizontal bandsaw

• oxy-acetylene

  • a high temperature gas mixed with acetylene and pure oxygen to heat up metal and then cut a hole with the flame pressure

  • portable, versatile, thin and thick cuts, dangerous

• Plasma cutter

  • shoots pressurized air over an electrode and creates a circuit with the metal piece being cut. the circuit is strong enough to melt the metal and the pressurized air shoots a hole through the molten piece

three different ways to drill into metal

• drill press

  • different materials need different speeds (steel slower than aluminum cause its denser)

  • smaller diameter cutting tool needs to go faster than a larger diameter

• Knee mill

  • 3 axes (large ones) 2 axes (desktop ones)

  • angled cuts, holes, slots, and pockets

• CNC milliing

  • subtractive prices using milling cutting tools to remove material

• Lathe

  • high accuracy tool that moves a cutter bit along two axes to cut circular items known as ‘turning’

what are the parts of a drill press?

types of tube bending (2)

• draw bending

  • the tube is bent using a machine

• manual rotary (compression bending)

  • using a bending die that has the desired bending radius, a rotary lever with an outside roller is used to shape the tube around the die

how must a tube be bent? what is the neutral axis

• beyond its yield point

  • the materials capacity to resist permanent deformation

• not past its ultimate tensile strength

  • the limit of the materials ability to resits tearing

• the tube is then bent, and undergoes distortion, the material outside the bend stretches and the material inside the bend compresses

• neutral axis

  • a boundary line between the tension and compression zones

  • bending operations are calculated from its location

what are the two types of welding?

• forge weldoing

  • heat up the (iron based) metal to almost its melting point and hammer two pieces together in order to fuse them together

• arc welding

  • creating a very high current, using an electrical arc to melt metal. the arc is created by applying voltage across two separated conductive electrodes until an electrical path is created through the air gap. the arc melts the metal together along either a filler material made from a consumable electrode

shielded metal arc weld - what is it (4)

• shielded metal arc welding (stick welding) (SMAW)

  • most versatile and common

  • welding rods (electrodes) are covered in a coating of hard flux that melts and deposits as slag, the slag is then removed with a hammer afterwards (is brittle and will break off)

  • power source can be AC or DC

  • to create arc, electricity needs to flow from electrode back to source, so the workplace needs to be grounded. to do that we calmp the negative wire to the workplace

arc weld types (3) (just names)

• shielded metal arc welding (SMAW) (stick welding)

• metal insert gas welding (MIG)

• tungsten inter gas welding (TIG)

what’s metal inert gass welding

• MIG welding

  • most simple , most common in industrial practices

  • uses argon shielding gas to protect the molten metals from the atmosphere

  • the electrode is a wire spool and machine-fed

  • when the trigger is pulled, the arc is formed and the wire is fed

what’s tungsten inert gas welding

• TIG welding

  • using a tungsten electrode that will not melt

  • sometimes a filler wire or thin rod is manually fed into the weld (usually stainless steel)

what are the types of welds (3)

• tack

  • small, temporary made with filler metal to hold metal parts in alignment prevent thermal distortion

• bead

  • single continuous line of solidified metal deposited along a joint

• spot

  • resistance welding that joins overlapping sheet metal by passing a high electrical current though localized points while clamping with copper alloy electrodes

types of joints used in welding (5)

• butt

• lap

• tee

• outside corner

• edge

types of metal used for sheet metal (5)? how is sheet metal sold?

• stainless steel

• cold rolled steel

• pre-plated steel

• aluminium

• copper brass

• as a flat sheet or in coils

How is sheet metal thickness measured? why is gauge thickness not always the same in diff materials? how can steel sheet metal be sold ?

• imperial, metric, gauge

• because of historical situations where copper gauge and steel gauge was used in different industries and produced in different mills

• mild steel, cold rolled, or hot rolled plated with zinc for corrosion protection

what is perforated sheet metal used for? what’s another name for it? what is the connection between gauge and thickness?

• used as a decorative element, to lower the weight, to allow for sound to pass through, or to permit airflow

• as gauge increases thickness decreases

what can sheet metal be used fro? why is it used?

• computer chassies

• chairs

• light fixtures

• spekaers

• toys

• it is strong and relatively inexpensive

what is sheet metal siding? (2) what’s an early example of corrugation?

• an inexpensive durable way to have siding for a structure

• usually corrugated (folded) in some pattern to add strength - each corrugation acts as a mini beam and thus resists bending

• used by early plane manufacturers, steel was heavy so they made it really thin, in order to add strength they corrugated it

three types of sheet metal cutting

• manual cutting

  • sheer

  • nibbling

• plasma cutting

• digital programed cutting

  • laser jet

  • waterjet

what are ways of manually cutting sheet metal (2)

• shearing

  • hand held - good for thin and softer metals, cut edge curls

  • bench mounted - can cut thicker (mild steel - 14 gauge, aluminium 14 gauge, stainless steel - 18 gauge)

  • floor mounted - cut very straight, used to cut larger sheets, usually foot operated or powered electrically

  • will usually have some ‘roll over’ on the edge

• nibbling

  • rapid small-stroke punch and die to remove tiny overlapping pieces of material, allowing you to cut complex curves, straight lines, or interior holes without destroying the metal

ways to digitally program cut sheet metal

• laser cutting

  • a laser beam goes through a focused leans, and out the nozzle, it is fast and economical, requiring simple programming. It can cut complex cuts easily

  • can cut through plastic, wood, and metal - metal is harder to cut because it is reflective

  • can be combined with a turret machine to create features such as louvres

• waterjet cutting

  • guided by CNC machinery, cuts thick materials with a hypersonic water stream with abrasive filler that cuts through steel and aluminium easily

  • less expensive than laser cutting

  • more noisy and more messy

  • start at 60k

two ways of forming sheet metals (no def)

• brake bending

• punching

types of break bending (2)

• finger break

  • features a row of removable “fingers” of varying widths used to bend sheet metal into three dimensional shapes (the green one in Pauls lab)

• press break

  • clamp the workpiece btw a movable upper tool (punch) and a stationary lower tool (die)

what is spring back and what are its factors?

• you must overbend your metal slightly because it will spring back.

• this is because the material both undergoes elastic (bends back) and plastic (stays bent) deformation and the elastic deformation (stress is less than the yeild strength) will go back to its original state

• usually we bend a test one and see how far extra we need to bend it or we bend and check

  • spring back increases with bend radius and it increases with the materials yield strength

what is the anatomy of a bend (6)

• neutral axis is the middle line going through the piece of metal

• compression is the inside bend

• tension is the outside

• bend line is the last point the metal is straight

• bend allowance - the amount of material that is bent

• flange length - length of the bar when bent

what’s minimum bend distance/radius

• smallest inside radius a metal can be formed to without causing surface cracking, structural weakening, or breaking

what’s corner relief

• a small cut or notch made at the intersection of two or more 90 degree bends to prevent tearing, cracking, bulging, and dimpling, and to ensure accurate corners

what are 4 different kinds of specialty bends sheet metal

• step bends (curves)

  • taking a large bend radius and dividing it up into multiple bends in order to approximate a larger radius

  • cannot do with perforated sheet metal (cause the holes are random)

• hem bend (stringer edge)

  • an edge of sheet metal that is bent 180 degrees and flattened on top of itself

  • using a press break and a large die

  • can be done on any material as long as it doesn’t exceed the maximum thickness

  • needs minimum size of half an inch

• internal bend (internal flange)

  • bend that is placed on a particular area of a part where material surrounds the bend rather than on an outermost edge

• jog bend (2 operations) / material offset bend (1 operation)

  • flat, up diagonal, flat

  • used for adding clearance to a design

  • parallel distances (jog bends can achieve further distance

• W bend (back bend)

  • to form deep u shapes profiles

what is machine punching? (3) what are punch features? (4)

• machine that uses hardened steel tools that punch through the sheet metal using digital code

• versatile and fast

• used for complex sheet metal parts and compatible with high volume production

• hole patterns,

• hinges

• lock tabs

• louvres

what are slot and tabs for? (sheet metal) how can they be named (3)

• helps align parts accurately for welding

• can be laser cut, water jet, or pumched

what are self clinching fasteners?

• threaded or non threaded device that is permanently inserted on sheet metal

• panel faster

  • tools device installed on the outside of the mounting part - has a threaded stud on a spring that allows you to push and fasten into a threaded resepticle

• tie down fastener

  • give you a hint inside the enclosure to organize and tie up cables

• stud

  • permanently threaded screw in enclosure that can be used for mounting or grounding components

• pilot pin

  • unthreaded rod that can be used for locating components in enclosure

• threaded nut

  • for mounting parts

• right angle fastener

  • lets you thread into part at a 90 degree angle

• standoff

  • internal thread used to mount things

• blind nut

  • encapsulated internal thread to prevent foreign material from entering enclosure

• flesh nut

  • mounting point

what is spot welding?

• resistance spot welding

  • an electrical resistance welding process used to join overlapping sheets of metal together at a distinct, localized point

what is the product lifecycle ? what is the holistic lifecycle approach? what’s the cradle to grave concept?

• raw material - transportation - processing - transportation - retail and use phase - end of life

• rather than treating design, production, marketing, and disposal as isolated steps, a holistic strategy sees the process as a whole, and designs for circularity

• that everything you make is going to end up in landfill eventually, so you have to think about the product lifespan and its environmental, material, and energy impacts across every stage pf its existence

what is metallurgy? physical? chemical?

• the study of metals

• physical

  • science that looks at the properties of metals and how they are controlled and monitored in the production of raw metal materials, such as tubes and bars

  • focuses on the mechanical properties of metals and methods to enhance them

• chemical

  • chemical science behind understanding the extraction of ore and how it is chemically processed into desirable raw materials. (understanding atomic structures and how they are achieved)

  • involves extracting metals, reducing their oxidation, and preventing corrosion

what are the physical properties of metal ?

• hardness - does it resist scratching and indentation

• elasticity - is it flexible, (springs)

• toughness - how much can it withstand without breaking

• ductility - is it possible to stretch it (can it be drawn and pulled into wire)

• conductivity - does it conduct electricity

• oxidation - does it rust

how do we test hardness in metal

• Rockwell standardized hardness test

  • its a standardized test that uses a repeatable method by using a diamond pointed inventor, to measure how far the indenter travels into the specimen for a specific load

what are two internal forces? explain them

• compression

  • steel beams can buckle if the stress of compression is too high

  • uses calculations with cross sectional geometry and slenderness ratios

  • brittle materials such as cast iron are good in compression

  • as cross section reduces, stress increases

• tension

  • when subject to tension, brittle materials tend to crack and break. if the materials too ductile it may stretch

  • steel tends to be elastic and ductile, allowing it to be used in tension rather than compression

  • when steel is pulses it is very string, but if its compressed, it will buckle

what are beams? what is the strongest type of beam / why?

• they are unique structures because they experience both internal compression and tension force - steel is used in beams because iron is not good with tension and will tear

• H beam / I beam

  • most of the mass is placed into the top and bottom flanges, sitting as far away from the neural centre axis as possible

  • the ‘web’ in the middle resists vertical shear forces

  • provides superior stiffness and bending resistance while using less material

what does a tensile testing machine measure and how>

• it measures elasticity, ductility, and toughness

• it clamps two sides of a piece of metal and using hydraulics exerts a force to elongate the metal, the elongation is measured as a percentage

what is stress?

• how much force you put on a certain area - the stress on a smaller cross section is higher than on a thick cross section when the same amount of force is applied

what is the stress strain curve? what’s the equation? what does the graph depict?

• the output of the tensile testing machine -

• its measures as strain (elongation/original length = % of elongation)

• initial stage - specimen will elongate in an elastic fashion (straight slope of the curve) -

  • if force is removed from the specimen at this point, it will not undergo any permanent deformation, it’ll return to its original shape

• the specimen will reach its yield strength where it will then deform plastically (undergoing permanent deformation.

• ultimate tensile strength is then reached, then the material will fail and fracture

what’s the engineers job vs the designers job

• engineer - to calculate loads and strengths of materials

• designer - design in such a way that implements principles to make their designs last longer, be stringer, and also use less material and weigh less

what is iron (1) and why do we smelt it? (2)

• iron is an element found in nature

• it is rarely found pure in nature so smelting is a process used to strip away oxygen, freeing the pure metallic iron while impurities turn into waste

• the pure iron is then too soft to work with, so it is melted and mixed in with other metals to create a string alloy

what is bloomery? blast furnace, how does it work?

• an ancient technique for smelting iron ore in a clay oven - the iron melts and collects a the bottom as an iron bloom

• blast furnace

  • a replacement for the bloomery , bigger and better

  • permanent and continuous

  • layers of iron ore, coke, and limestone are continuously charged into the top of the tall steel stack - presurized hot air is blow under high pressure into the lower section - hot air burns the coke, making it hotter, limestone and iron melts and collect at bottom - iron is denser so it falls to complete bottom and gets drained

  • the output from a blast furnace is named pig iron - it has a high carbon content (3.5-4.5%) - high carbon makes it brittle and not usable w/o further processing

what is steel? how was it made back in the day in Japan?

• iron with very very low carbon content - can also be called wrought iron

• the worker would heat it up and beat it with a hammer. the carbon reacts to the high temperature and the hammering removes the carbon - creating steel

what is cast iron? what’s the bessemer process?

• steel with high carbon content , quite brittle, but good for making parts like internal combustion engines - it is also easier to melt iron than steel to put into moulds cause it has a lower melting point

• a machine that burns off the carbon from the iron by forcing air though a furnace at a high speed - it creates a lower quality steel though due to the inability to remove sulphur present in the ore

what are steel sustainability concerns? (3)

• steel production is a suer polluter

• steel production accounts for 8% of the woulds CO2 production

• it consumes a lot of energy

what has the bessemer process been replaced by? what are new different forms of steel (2)?

• the basic oxygen approach

  • more controlled and cleaner

  • draws out unwanted phosphorus by hitting it with a very pure blast of oxygen that converts it into a form that is absorbed in the slag, which is then separated fro the steel

• hydrogen steel (hydrogen based direct reduction)

  • uses hydrogen to bind with oxides in the iron or e to reduce it into iron and water instead of iron and CO2

• green steel

  • electric arc furnace uses a high content of recycled scrap to make steel. an arc is made btw 3 carbon electrodes that are immersed in the mixture of metal and melt the metal

steel vs iron (3)

• iron

  • hard

  • brittle

  • easily cast into shapes

• steel

  • maleable

  • tough

  • versatile and comes in many different grades of alloy

iron in construction(1)? what is steel used to make (6)

• Quebec bridge collapse

• buildings

• cars

• ships

• furniture

• appliances

• hardware and tools

types of steel?

• carbon steel

• low carbon steel (mild steel)

  • most common type of steel

  • strong, versatile, easy to cut and weld

  • carbon content less than 0.3%

• medium carbon steel

  • 0.3-0.6% carbon

• high carbon steel

  • 0.6-0.9% carbon

• alloy steel

  • steel is already an alloy, but other metals are added to improve corrosion, resistance, hardness, and mechinability

  • tend to be used when the application demands a steel that has specific properties

• stainless steel

  • normal steel corrodes easily with exposure to water and salt, so this steel is made with a significant amounts of chromium for rust protection

• tool steel

  • contains specific carbide-forming elements that allow it to shape, cut, stamp, and mold other materials without rapidly losing its structural integrity

  • high hardness (even when heated)

  • water resistant

  • tough

why do they do heat treatment on steel and (2)? what Is heat treatment for steel? (2)

• to soften a higher carbon steel so that it can be welded to machined , then quenched to regain hardness

• used to alter the grain structure of steel to soften it or used to harden the part

• annealing-softening steel

  • the steel is heated to the annealing temperature and then allowed to cool slowly

  • removes stresses and makes the steel softer

• quenching-hardening of steel

  • the steel is heated to the appropriate temperature and cooled instantly by quenching in water or oil

  • this hardens the steel (at least on the surface)

what type of steel do most common applications require? what is the young modulus? for steels?

how does yield strength differ across types of steel?

• mild or low carbon steel

  • automotive or aviation and space may require alloyed steel with special performance requirements

• the young modulus (stiffness and deflection) of all steel is pretty much the same

• yield strength is lower for low carbon steel, making it easier to bend and weld