ENME 221

the runners and sprite of an injection mould are not recyclable (T/F)

False

under tension the stress on a thread is shared evenly over all threads (T/F)

False

using common datum features is an example of DFA (T/F)

False

it is equally easy to achieve a tolerance level on a small part as it is a large part? (T/F)

False it is harder on a larger part

how does a cutting tool wear?

Fast-slow-fast wear rate. (W7L1)

minimising the number of parts and standardising parts are examples of DFA (T/F)

True

repressing is a press operation to compress sintered part in a closed die to improve sizing? (T/F)

True

standardising the size and type of fastener encourages DFA? (T/F)

True

there is no sprue and runner in compression moulding (T/F)

True

true or false: end mill cannot drill into the work piece

True. end mills always start from the end of the work piece. (W8L3)

What is the calendering process?

a series of rolls used to reduce thickness to desired gauge. (good surface finish, high gauge accuracy, an extrusion process) (W6)

what are four common materials used in abrasive materials?

aluminum oxide, silicon carbide , cubic boron nitride and diamond (W8L3)

What happens to the chemical structure of thermosets when heated?

causes permanent change in molecular structure, cant be remelted (W6)

what is a common material for cutting tools

cemented carbides? (W7L1)

what is the gating system in a closed mold?

channel through which molten metal flows into cavity from outside of the mould. (W8L2)

how often should cutting fluids be replaced?

every 10 days (W7L1)

what causes bolt stripping or the thread to be torn out of the nut

excessive load, over tightened, weak materials, insufficient thread engagement length

the basal seam on plastic moulds is indicative of which process

extrusion blow moulding

what are the three type of blow moulding?

extrusion blow moulding, injection blow moulding, Stretch blow moulding (W7L2)

what are the five different types of milling?

face milling, end milling, profile milling, pocket milling and surface contouring (W8L1)

why use riveted joins on assembly line

fast, reliable, unskilled labour

why are multi-lead screws beneficial in biomedical applications?

faster insertion time (W9L1)

how are sheet and films different

films are less than 0.5 mill(W6)

what is thermoforming?

flat thermoplastics sheet or film heated and deformed into desired shape using mould(W7L2)

When is injection moulding economic?

for mass production due to high cost of mold (W6)

how can cutting tools fail?

fracture failure, temperature failure, gradual wear(W7L1)

what is a discontinuous chip when machining?

from working with brittle materials, low cutting speeds and large feed depth. (W7L1)

what a permanent moulds?

good as they can be reused, but the must be able to open to remove the product. (W8L2)

which is not true about washers: they can reduce vibration they can reduce loosening they can help distribute loading they must be flat

they don't need to be flat (belleville washers for example)

you are designing a machine that requires a cylindrical lever that must have an anti-slip surface on it. what processes should be used?

knurling (W8L3)

what producducts can be produced with Thermoforming?

large items like bathtubs and clear plastic packaging (W7L2)

what welding to weld car door together in assembly line

lazer

what is the best casting method for a complex part

lost wax casting/ investment casting(W9L2)

what are properties or polymer foam

low density, high strength per unit weight, good thermal insulation, good energy absorbing qualities(W7L2)

when is casting suited?

low quantity production(W7L2)

what is reaming?

slightly enlarges hole and has a more accurate toerance on diameter, as well as a better surface finish(W7L3)

a 25 mm long slot must be pocketed into a shaft, 8mm wide for the key. which mulling cutter would be chosen?

slot drill (W8L3)

which DFMA solution would be appropriate for eliminating threaded fasteners

snap fits

what type of welding process for joining a sheet metal case for control panel

spot welding

what is the two most important materials for implants?

stainless-steel (326L) and 5th grade titanium (W9L1)

in which properties do plastics outperform metals

strength to weight ratio, corrosion resistance, optical properties

what used to weld seam of pressure vessel

submerged arc welding

are symmetric or asymmetric geometries easier to assemble

symmetric

what nut would you use to dig into soft materials

tee nut

treatment for reducing the brittleness of martensite is called

tempering

where does the word plastic come from?

the Greek word plastikos which means 'able to be moulded' (W6L1)

How is plastic moved around a injection moulding mould?

the Sprue leads from nozzle in to the mould, runners then lead from the Sprue to the mould cavity while gates constrict the flow of plastic. (W6)

what is the vernia measurement principal based on

the alignment of lines

what is the main difference bettween horizonal and vertical milling?

the cutting tool. a vertical tool tends to be long and thin while horrizontal is thinker and stronger so its used to remove more material (W8L1)

what does a grinding wheel A-36-L-5-V-23 stand for?

the first letter shows abrasive type, aluminum oxide, the second shows grain size, the 3ed shows hardness A being soft z being hard, 5 shows the wheel is dense 1-8 8 being dense(not always given). the last letter is the type of binding agent(W8L3)

what equation calculates the minimum energy neededto work a material?

the merchant equation. (W7L1)

what could a wash defect in a casted piece be due to?

the metal being to hot or the result of turbulence(W9L2)

what is the most important part of casting?

the mould (W8L2)

What is machining?

the process where material is removed by a sharp cutting tool, e.g. turning milling drilling(W7L1)

what does melting refer to for plastic moulding?

the softening of a material to a thick liquid (simular to honey). We call this a "polymer melt". (W6)

what is the trade off for hex screws

the space around the head for tightening

how much heat is required to mould metal

the sum of the heat needed to reach melting pointm heat of fusion to convert from solid to liquid and the heat to raise molten metal to for pouring (W8L2)

in casting total solidification is defined as

the time between pouring and complete solidification

for the grinding wheel to be able to move at high speeds what has to be true?

the wheel must be precisely balanced (W8L3)

what type of plastic is used widely for compression moulding?

thermosets (W7L2)

what are chills in casting

they are heat sinks that cause rapid freezing in certain regions of the casting, they are designed to prevent voids in the part(W9L2)

what type of nut if it must not come loose

castle nut

why is turbulence bad?

is undesired as it eats away at the walls of the mould (W8L2)

In solid works how do you - search for a command

S (W5L1)

draw an injection moulding machine

(W6)

what is a positive and negative rank angle? (draw it)

(W7L1)

draw a diagram of compression moulding

(W7L2)

draw a diagram of transfer moulding

(W7L2)

draw a closed mould and open one

(W8L2)

the difference between metals and polymer properties should be known

(W8L2)

draw centerless grinding

(W8L3)

here is a table of abrasive processes

(W8L3)

what are the 3 steps in grinding wheel wear?

(W8L3)

when would you use a countersunk screw

when the head must be below the surface

what size range can injection moulding be used for?

50g to 25 kg, like a car bumper (W6)

how long does it take to machine one screw for medical use?

7 min, this is an example where high precision outweighs reducing cost (W9L3)

what material should be used when ginding steel and most cast iron?

Aluminum oxide (W8L3)

Fused Deposition Modelling (FDM)

- "Hot glue gun" - Cheap systems use one nozzle (support must be broken away) - Sophisticated systems have 2 nozzles, support dissolved away. - applications: electrical, jigs, fittings

Wireframe model

- Describes shape using only EDGES - Misinterpretations likely - Bodies overlap, difficult in CAD

Steriolithography (SLA)

- Material laid down, UV light cures material where needed. - Only one material can be printed at a time - jewellery, dental applications

3D Printing

- Powder laid down and inkjet squirts fluid to bind it - Full colour range - Low strength parts - Health and Safety regarding breathing or volatility of powder

Selective Laser Sintering or Melting (SLS or SLM)

- Powder spread down in small thickness - Laser or Electron beam fuses material - Used for metals and plastics - Health and Safety regarding breathing or volatility of powder - complex ducting (hollow), long run part production

Surface model

- Represented by individual surfaces - Dependencies can be defined - Cutting surface results in LINES - Includes: Translation, Rotation, Guided, Transition surfaces

Polyjet

- Similar operation to an inkjet printer - Material squirted from print head, UV light cures it. - Allows for fine detail - Multiple materials can be used at once - Full colour - Allows various types of support and removal processes

Why is layer height important?

- Surface finish - Printing speed - Part quality

Volume Model

- Surfaces rigidly linked together - Each component has defined volume - Cutting surface results in SURFACE - CAD can detect collisions and penetrations - More useful - Volume created from: Extrusion, Rotation, Translation, Transition

what are three key differnces bettween compression mouliding and transfer moulding

1. TM produces scrap(TS plastics cant be reused) 2. TM produces more intricate part shapes than CM 3. TM lends itself to moulding with inserts like metal or ceramics (W7L2)

What are the two steps in blow moulding

1. fabrication of starting tube 2. inflation of tube to desired final shape (W7L2)

what are some properties of compression moulding

1. limited to simple parts 2. required the mold to be oriented vertically 3. non sprue runner system (W7L2)

what are the 4 steps in sand casting?

1. pour molten metal into mould 2. allow metal to molidify 3. break up the mould to remove casting 4. clean and inspect casting(W9L2)

what is the effect of high cutting temperatures

1. reduce tool life 2. produce hot chips that pose safety hazards 3. can cause inaccuracies in part dimensions due to thermal expansion(W7L1)

what are the three tests used in bone screws?

1. the static torsion test to find the max torque. 2. pull- out test to predict the force needed to remove the screw from the bone. 3. self-tapping force required(W9L1)

what is the cost of an injection moulder?

100-500 thousand (W6)

What is the difference between a 3 jaw and 4 jaw chuck?

3 jaw is self centering, 4 jaw is more accurate but slower to set up (W7L3)

which of the following statements about calendaring is false: 1)embossed surfaces are possible, 2)the surface finish is good, 3)high gauge accuracy is difficult to achieve, 4)starting materials are rubbery thermoplastics.

3)high gauge accuracy is difficult to achieve,

what sort of clamping force in needed for injection moulding

30-5000 tonnes, injection molding machines are rated by there clamping force (W6)

how many instruments are required in a successful surgery?

300 (W9L1)

What is blow moulding?

Air pressure inflates soft plastics in a mould cavity (W7L2)

what is serrated chip when machining

Associated with difficult to machine metals at high cutting speeds. (W7L1)

what typer of washers are dish shaped to provide spring

Belleville washers

What is blown film extrusion?

Combines extrusion and blowing to produce a tube of thin film. makes plastic bags (W6)

What is the Extrusion process

Compression process in which material is forces through a die orifice to provide long continuous product (W6)

what type of welding is used for seam welding pipes or tubes

EWR (electric resistance welding)

how is the part ejectied from a mould in injeciton molding?

Ejector pins are bulit into the moving half of the mould. (W6)

In solid works how do you - open the last function that you used

Enter (W5L1)

list 3 examples of thermosets and 3 examples of Thermoplastics respectively

Epoxies, phenolics, polyimides - Acrylics, ABS, nylons (W6)

what is roational moulding?

Gravity spreads the charge of TP powered around all surfaces in a heated mould (W7L2)

In solid works how do you - open recent files

R (W5L1)

what is the technical term for a square hollow beam

RHS

how is Rate of material removal computed?

RMR = v f d, v is cutting speed, f=feed, d = depth of cut (W7L1)

What are the two types of cuts when machining.

Rough and finishing. rough makes large cuts while finishing cuts produce the final dimensions. (W7L1)

what type of plastic can be used for thermoforming?

TP(W7L2)

Polymers used in Additive Manufacturing (AM)

Thermoplastic: Can be re-melted and fused Thermoset: Fused via UV light and can't (generally) be melted

What are the three types of plastics

Thermoplastics, Thermosets and elastomers(wont be covered) (W6)

What is the most common type of plastic?

Thermoplastics, making up over 70% of all plastic tonnage (W6)

Angularity

What is this symbol

Circularity

What is this symbol

Concentricity

What is this symbol

Cylindricity

What is this symbol

Flatness

What is this symbol

Parallelism

What is this symbol

Perpendicularity

What is this symbol

Profile of a Line

What is this symbol

Profile of a Surface

What is this symbol

Runout

What is this symbol

Straightness

What is this symbol

Symmetry

What is this symbol

Total Runout

What is this symbol

True Position

What is this symbol

Do all systems require support material?

Yes, any print could have an overhanging feature, which requires support material

which plating metal is associated with galvanising

Zinc

what is the effect of the rake angle on energy and force needed to cut

a higher rake angle causes a smaller shear force and therefor a less energy needed to cut. (W7L1)

How are hollow shapes produced in the extrusion process

a manderial is needed. the material melt flows around the spider legs. an air channel is required to maintain the hollow profile once it exits through the die (W6)

What is the lost wax/investment casting process

a pattern made of mx is coated with a refractory material to make a mould (W9L2)

what is polymer foam?

a polymer and gas mixture that gives the material a porous or celluar structure (W7L2)

what is hydroxyapatite?

a special type of surface coating which contains calcium. it allows the process of bone formation around the implant. this is an important feature that promotes fast recovery(W9L1)

what is the slowest shape to solidify in casting?

a sphere as it has the highest volume to surface ratio(W9L2)

what is honing?

abrasive process performed by a set of bonded abrasive sticks using a combination of rotational and oscillatory motions (W8L3)

what would a deviding head be typically used for?

accurately spacing gear teeth(W8L3)

what are the advantages and disadvantages of casting?

advantages -create complex parts, produce large parts, can suit mass production disadvantages - poor dimensional accuracy and surface finish, safety hazards for workers. (W8L2)

what does freezing mean?

allowing the metal to lower to room temperature (W8L2)

draw an image of the extrusion process equipment

answer (W6)

why is the specific energy of grinding high?

as the ration of machining power to removal rate is high. this is due to small chip size and not all grit is used in cutting at once. (W8L3)

which design guideline for powder metallurgy parts would be recommended: Avoid... 1) 45 degree chamfers 2) screw threads 3) vertical keyways 4) non round holes

avoid screw threads

What is the difference between the moulding procedure for thermoplastics and thermosets?

before plastic sets thermosets are heated further while thermoplastics cool instead (W6)

describe the temperature in sintering

below the melting point of the powder material

what are small grit sizes good for?

better finishes and use on hard materials. (W8L3)

why use a fine thread screw over a course thread screw

better strength and more resistant to vibrational loosening

a parison is associated with which one of the following plastic shaping processes

blow moulding

what is a boring machine?

boring is performed on the inside diameter of an existing hole.(W7L3)

butt vs miter weld

butt: poor strength but open section miter: good strength but closed section and more difficult to fit

transition fit

can be pushed through

clearance fit

can slide

what is a chaplet in sand casting?

chaplet is a support to hold the core during pouring. these ensure that the core stays concentric within the mould when the molten metal enters the mould, they end up as part of the casting(W9L2)

what do the three classes of medical devices stand for?

class one devices are low risk(epi pen) while class three devices are high risk(implants)(W9L1)

In solid works how do you - only make a single line

clicking a dragging on the line tool, rather than clicking and clicking (W5L1)

which has the better surface finish cold work or hot work?

cold work

what is the propose of the gate in plastic injection moulding

control the flow of melt into the mould

what is the difference between cortical and cancellous bone and what does this mean for the tread of screws used?

cortical bone is dense while cancellous bone has lots of air gaps. this means that the thread used is deeper for cancellous bone.(W9L1)

what is the error associated with dial test indicators

cosine error

where does gradual wear on a tool occure?

crater wear, on time rake face and Flank wear on flank face(W7L1)

what is creep feed grinding?

creep- feed uses a heavier grinding depth and a slow transvers rate and a profiled grinding wheel. this leads to a high material removal rate(W8L3)

what material should be used when ginding aerospace alloys?

cubic boron nitride (W8L3)

in what direction must thread tape be applied

cw

how to avoid damage due to high heat when using grinding?

decrease the infeed, reduce wheel speed, use an open wheel structure, use a cutting fluid(W8L3)

is open or dense grinding wheels better for a close surface finish?

dense(W8L3)

what material should be used when ginding hard abrasive matereials such as ceramincs?

diamond (W8L3)

In solid works how do you - move back to the origin

double clicking the middle mouse button (W5L1)

what is continuous chip when machining?

ductile materials, high cutting speed and small feeds and depths (W7L1)

why does the die for a squear shape (in extrusion processes) have to be star shaped?

due to the final extrudate being larger than the extrusion die profile. (W6)

what are principles of DFMA

eliminate or reduce adjustments open tolerances as much as possible standardise materials and use common parts eliminate or reduce adjustments

what are the diffent types of sand moulds and what type of sand is used?

green sand mould, cold box moulds and dry sand mould. using foundry sands(W9L2)

what faster for joining two shafts

grub screw

what do you use for a hydraulic ram shaft

hard Crome bar

what pipe for plumbing

hard copper tube

what material properties must be considered when choosing a grinding material

high hardness, wear resistance , toughness , friability.(W8L3)

what do you use for a cutting tool

high speed steel

what material for a thin walled bush

hollow circular bar

what is a biproduct of magnisum corrosion in the body?

hydrogen gas, this can result in cavitys in the body is the corsion rate isnt slow enough .(W9L3)

why are expandable screws beneficial in biomedical applications?

makes more integration between the screw and bone (W9L1)

what is grinding?

material removal process using abrasive particles contained in a bonded grinding wheel at very high surface speeds(W8L3)

what is the purpose of limits and fits

maximise the interchangeability of parts

what are the three steps in casting metals?

melting, pouring and freezing(W8L2)

what joining technique for boat trailers

metal inert gas welding

which term is correct for the science of measurement

metrology

according to Abes principal which is more accurate a verina caliper or micrometer

micrometer (measurement axis closer to axis being measured)

what is broaching?

moves a multiple took cutting tool linearly relative to work in direction of tool axis (W8L1)

In solid works how do you - change the view

pressing the space bar (W5L1)

interference fit

needs to be forced

Can thermosets plastics be used in a extrusion process?

no (W6)

should bone screws be 3d printed?

no as much tighter tolerances are needed. (W9L1)

What happens to the chemical structure of thermoplastics when heated?

nothing (W6)

when would galvanised fasteners be required the most

outdoor applications

what are the two main errors when measuring

over-tightening and parallax

how is the mould cooled in injection moulding?

passage ways in the mould distributes water though the mould. (W6)

What is injection moulding

polymer heated to a highly plastic state and forced into a mould cavity where it solidifies; moulded part removed (W6)

how are wire coated using extrusion

polymer melt coats bare wire its pulled through a die, a slight vacuum is needed between wire and polymer (W6)

what is casting for plastics?

pouring liquid resin into a mould, using gravity to fill cavity allowing polymer to harden(W7L2)

what is a expendable mould?

processes involving making the mould and breaking it apart to get the product out. better detail can be achieved because the mould has no limitations(W8L2)

what is 2 advatages or grinding?

production of very find finishes - 0.025 nm and very close tolerances possible (W8L3)

what is an important factor to control with biodegradible implants?

rate of mass loss/ corrosion(W9L3)

what are large grit sizes good for?

removal of material and use on softer material(W8L3)

what is a riser in a metal mould?

reservoir in the mould witch is a source of liquid metal to compensate for shrinkage (W8L2)

which process would be used to manufacture a large polyethylene water tank

rotational moulding

what is the most widely used casing process?

sand casting(W9L2)

what is mould for metal made out of normally?

sand or ceramics (W8L2)

what do you use to make the legs for a workshop table

seam welded rectangular cross section

what is the best faster of container and lid (high volume)

self fastener (snap fit)

how can it be easier to align washer and holes

self locating washer

what is the difference between shaping and planing?

shaping is where tool moves and the job is fixed while planing is where the job moves (W8L1)

what type of products are produced from Calendering?

shower curtains, pool liners, inflatable boats. (W6)

what material should be used when ginding non ferrous metals

silicon carbide(W8L3)

What are the two types of cutting tools?

single point tools and multipoint tools (W7L1)

what is the most likley failure cause for a high tensile bolt, nut and washer in high vibration environment

sliding between the plate due to insignificant clamping pressure

what is the differnce bettween through holes and blind holes?

through holes go all the way through the material but blind holes doesnt exist the work (W7L3)

why does the melt pass through a screen pack?

to filter contaminants and hard lumps as well as straightening flow (W6)

what is the purpose of a gasket

to prevent leakage

to ensure a bolt is correctly tightened use...

torque wrench, rotation angle tool, micrometer to measure bolt stretch.

what are some key characteristics of cutting tools

toughness, hot hardness and wear resistance. (W7L1)

true or false: broaching is an ideal process when forming internal gears?

true. this is a slow process of gradually moving material to form a thread(W8L3)

What types of products are produced using the extrusion process

tubing, pipers, hose, structural shapes, sheet and film, continuous filaments, coated electrical wire (W6)

what is cold box mould?

use a binder that is not clay to hold the sand togeather, making it stronger than green moulding (W9L2)

two halves of a housing need to be aligned how should this be done?

use a dowel

what is the lost foam process?

uses a mould of sand packed around polystyrene foam pattern(W9L2)

what is lappint and where is it normally used?

uses fluid suspension of a very small abrasive particles between work piece and lap, normally used for optical lenses(W8L3)

why are surface finished important

wear, aesthetics, safety, assembly, electrical conductivity

37.46 mm

what is the measurement

7.37 mm

what is the measurement

0.5

what is the pitch

0.5/50 = 0.01

what is the resolution

1/50 = 0.02

what is the resolution

feature control frame

what is this symbol known as

a higher number for surface finish indicates a better or worse surface finish

worse

if a hole has a tolerance of ø8H9 which translates to ø8mm +0.036 -0.000 what is the LMC?

ø7.964mm

if a hole has a tolerance of ø8H9 which translates to ø8mm +0.036 -0.000 what is the MMC?

ø8mm