Exam Prep Flashcards
A shaft is to be rough machined on a lathe and then cylindrically ground on two surfaces. What feature should be added to allow concentricity of the machined and ground surfaces when swapping between machines?
Centre drilled holes
A high strength cap screw typically has what type of head?
Cylindrical with internal hex
MIG welding is often used for manufacturing steel frames like trailer chassis. What does the ‘M’ stand for?
Metal (MIG = Metal inert gas)
You are required to lap joint two pieces of sheet metal with a mechanical fastener but access to the rear side is not possible. Which of the following is a likely option?
Pop rivet
You are designing a large part that has a flat face and an irregular shape outer surface. A spigot on it must be turned on a lathe. Which of the following is the most likely option for holding the part in the lathe?
Four jaw chuck
Optical scanners for measuring irregular shapes typically come in two technologies. The department just purchased two. Which technology do they use?
White/Blue light
You have been sent to the hardware store to purchase a set of drills. One option appears to be polished steel and the other gold colour coated. What is the significance of the gold colour?
The surface is harder and more wear resistant
You have chemically machined a Lear jet body panel to reduce its weight but the sideways dimension is larger than the chief engineer designed and the dimensions of the masking hole. What is your most likely mistake?
To allow for sideways undercut under the masking
Your company is purchasing a new EDM machine. The ‘D’ stands for?
Dick Discharge (Electrical discharge machining)
Which of the following is NOT a typical drilling operation? Counter boring Reaming Countersinking Lapping
Lapping
You went to the gas store to get a gas bottle for TIG welding and brought back a bottle of oxygen. Why did the foreman laugh at you and send you back to the store?
The gas is used to remove oxygen
The swarf coming off a CNC lathe is tangling in the tool holder and machine time is being wasted removing it. What is NOT a likely solution?
Use a chip breaking tool
Increase the feed rate
Increase the rotating speed
Move the part further away from the tool holder
Move the part further away from the tool holder
The head of an engine exhaust valve must be welded to its stem.
Which of the following is the most likely method for mass production?
Manual stick welding
MIG
Spot welding
Friction welding
Friction welding
A turn buckle is needed to stretch a shade cloth. What is the special feature of the threads?
Right and left hand thread
Your company has just bought a production line for manufacturing HEX head bolts. What process is used for making the thread? CNC machining Drop forging Rolling Drawing
Rolling
Two halves of an engine housing are bolted together. Which of the following are special features to aid assembly? Dowels and spigots Neat fitting bolt holes and gaskets Rivets and splines Cast ribs
Dowels and spigots
You work for an aircraft manufacturer and the wings are held on by three bolts. Which of the following would you recommend to your boss for ensuring the nuts don’t come undone? Wire tied Split washer Nylock nuts Wing nuts Deez nuts
Wire tied
Which of the following is NOT an additive manufacturing process? FDM (Fused Deposition) Polyjet SLS (Selective laser) MAW (Metal arc)
MAW (Metal arc) , it is welding but is a developing concept
Which of these processes would be considered mass production of small steel gears? Powder Metallurgy Blanking Turning Shaping
Powder Metallurgy
Which of the following is a bulk deformation process? Milling Shaping Rolling Shearing
Rolling
The camshaft of an engine is normally? Mild steel Cast iron Sintered Brass Die cast aluminium
Cast iron
Annealed copper tube is? Difficult to bend Usually used for house plumbing Easy to bend Impossible to braze
Easy to bend
You work for a company making welded metal hand rails and artistic structures. You are required to design stair hand rails for the new University lecture block. What would be your first material choice? Mild steel Silver steel Stainless steel Commercial bright steel
Stainless steel
What does ‘MS’ stand for in MSDS? Manufacturing Systems Manufacturing Safety Material Safety Material Sales
Material Safety (data sheet)
You ordered 6061 aluminium T shaped extrusion. When it arrived the packing slip said Aluminium 6061 T6. What does T6 refer to? The shape of the material The material composition The material heat treatment The material surface finish grade
The material heat treatment
Hot rolling steel has what benefit? Makes the steel stronger Requires less force Polishes the outer surface Dimensional accuracy
Requires less force
For manufacturing flash less forging is preferred because? The material surface finish is better The material hardness is better Requires less finishing processes It is a safer process
Requires less finishing processes
A common use of drop forging is? Making thin wall cups Extruding fly spray cans Making spanners Making vices
Making spanners
Center less grinding is used for? Grinding cams on shafts Grinding gear teeth Grinding long rods Grinding square bar
Grinding long rods
A dovetail cutter is mainly used for? Making slides on machine tools Making grooves for keyways Making a recess for bolt heads Making sheet metal shears
Making slides on machine tools
The frame is to be welded together 50x50x3 RHS mild steel. What type of welding process should you choose? a. TIG b. Submerged metal arc c. MIG d. Gas flame brazing
MIG
The apprentice welder assembles the first frame and finds it is severely distorted.
What might he/she not allowed for and protected against?
a. Flux shrinkage
b. Choosing the incorrect welding equipment
c. Using the wrong weld filler material
d. Weld shrinkage
e. Cracking of the HAZ
weld shrinkage
The metal panel on the front is required for mounting instruments and has numerous cutouts. What is the most likely method of cutting the 1.5mm thick mild steel sheet? a. CNC machining centre b. Gas flame cutting c. CNC turret punch d. Hardened metal die set e. Tin snips
CNC turret punch
The equipment is exposed to the outdoor environment which will include rain and sometimes it will be used near the sea. What type of protection of the metal would you choose? a. Acrylic paint applied by brush b. Galvanising c. Brazing d. Laser coating e. Tin coating
Galvanising
After supplying the equipment the customer storms into the office hurling abuse at you. He was making a complaint about the LPG gas fitting. What should you have chosen? a. ACME thread fitting b. 30 degree parallel thread fitting c. Left hand thread fitting d. Threaded cast iron gas union fitting e. Parallel taper lock fitting
Left hand thread fitting
The ends of the tank must be formed from 1.5mm stainless steel sheet. What process would you choose to make them? a. Spinning b. Lapping c. Milling d. Shaping e. Extrusion
Spinning, (could use press for high numbers but very expensive)
To enable the frame to be lifted by a fork lift or to allow easy fitting of lifting ropes the frame will sit on metal skids welded to the frame. What is the most likely material shown? a. Hot forged universal section b. Cold forged universal section c. Cold rolled channel d. Hot rolled channel e. None of the above
Hot rolled channel, (cold rolled too expensive)
The front panel is attached with M8 bolts passing through the RHS. There is no
likely danger presented if the bolts come loose but it would not be good for your
reputation it they do. What would you most likely choose to prevent the bolts
loosening?
a. Use nylock nuts
b. Wire tie the nuts
c. Use castle nuts and cotter pins
d. Use flat washers
Use nylock nuts
There are many RHS parts to be cut to length. What machine would you choose to cut them? a. Skill saw b. Cold saw c. Slitting saw d. Band saw e. Reciprocating saw
Band saw
The tank is made from 1.5mm thick welded stainless steel sheet. Which of the
following welding methods should be your first choice?
a. Brazing
b. EBW
c. TIG
d. Submerged arc
e. Friction weld
TIG
.What technique is used for creating the head on standard Hex head bolts?
a. Rolling
b. Upset forging
c. Milling
d. Coining
Upset forging
Cap screws are normally?
a. Low Strength
b. Medium strength with a protective cap
c. High strength with an internal hex
d. High strength with a flat blade screw driver slot
e. Medium strength with an external hex
High strength with an internal hex
TIG and MIG welders use inert gas around the weld pool. Why?
a. To keep the weld pool warm
b. To quickly cool the weld to prevent HAZ effects
c. To project the weld pool from the atmosphere
d. To provide a gas to break down the oxide layer
To project the weld pool from the atmosphere
Your company makes small engines and it is making a new line for producing
500,000 engines per year. What process would you choose for making the
carburettor body?
a. Hard metal die casting
b. Sand casting
c. Powder metallurgy
d. Additive manufacture
Hard metal die casting
Your company mass produces aluminium products. A client requires long lengths of
material that can be cut to length and used for heat sinks for electronic components.
What process would you select?
a. Reverse extrusion
b. Rolling
c. Forging
d. None of the above and you lose the contract
None of the above and you lose the contract because ben cartwright is a cunt
(you would want forward extrusion)
You work in a general design shop that specialises in rapid prototyping. Which of
the following are you unlikely to have in your workshop for designing and making
making 3D prototypes?
a. FDM additive manufacture machine
b. SLA additive manufacture machine
c. Polyjet printer
d. Ink jet printer
d. Ink jet printer
Which of the following is a bulk forming process?
a. Drop forging
b. Rolling
c. Extrusion
d. All of the above
d. All of the above
Which of the following is a method of brazing?
a. Vacuum
b. MIG
c. TIG
d. FDM
a. Vacuum (cleaner)
An internal keyway is required in the bore of a cast iron gear. What process would be the best to use? a. Featuring b. Broaching c. Milling d. Turning e. Sawing
b. Broaching
- What is NOT a correct name for a process?
a. Milling
b. Lathing
c. Spinning
d. Shaping
e. Annealing
b. Lathing (always turning)
A tool is required to punch a hole through 100 firm material gaskets. Which of the
following materials and processes would a tool room use to make the tool?
a. Annealed commercial bright
b. Hardended and annealed tungsten carbide
c. Annealed silver steel
d. Hardended and annealed silver steel
e. None of the above
Hardended and annealed silver steel
In numerical control what process would use point to point systems
drilling (each axis moves independently)
In numerical control what process would use continuous path systems
milling, turning (axis move synchronized)
What are the different types of additive manufacture machines?
FDM- Fused deposition modelling (like hot melt glue, usually cheap if only one nozzle, uni is a big dog and has 2 nozzle one, Support is dissolved) SLA- Steriolithography (material laid down and cured with UV light, requires post curing, one material at a time) Polyjet-like inkjet printer (droplets of material squirted and cured on with UV light, multiple materials at once, very fine detail, elastomers) SLS/SLM-Selective Laser Sintering/Selective Laser Melting(Powder spread down in a small thickness, Laser or electron beam fuses the material, Metals and plastics) 3D Printing (Powder (ceramic, plaster) is laid down and an inkjet printer head squirts an ink type fluid to bind it, full colour, low strength)
What machine can be used for reverse engineering or for checking the dimensions and geometry of objects
3D Scanner (also good for recovering old parts with no drawings)
What is DP Fever
When all you can think about is Double Penetration
Whats is The most common form of steel
Hot rolled (used Reinforcing steel, I beams, angle, RHS, plate etc) It is black due scale left after hot rolling Paint may not attach well… May need to remove the scale by, for
example, sand blasting
Can be galvanised for corrosion protection
Available in a range of strength grades: Low, Medium and High
tensile steel
Relatively poor dimensional accuracy
Silver Steel is: a) Most typically used for shafts on hydraulic rams b) Is an alloy of silver c) Able to be flame hardened d) Easily cut with standard hand tools
C, Able to be flame hardened
Which has better dimensional accuracy, hot or cold rolled steel?
cold
Car exhaust are often made from:
a) Thin wall seam welded RHS
b) Thin wall seam welded tube
c) Annealed copper tube for easy bending
d) Hard copper tube for neatness
B,Thin wall seam welded tube
What are normal drill bits made from:
a) High speed steel
b) Tungsten carbide
c) Annealed mild steel
d) Flame hardened silver steel
A,High speed steel
The most used UOC 3D printer is:
a) SLA
b) FDM
c) SLS
d) SLM
B, FDM like hot melt gluie
Cold Rolled Steel is also called
“Commercial Bright” (Due to the last roll forming operations being cold the scale
detaches)
Which has better dimensional accuracy, hot or cold rolled steel?
cold
What material section would you use to make a roof
Sheet (Black or Bright) Available in cut sheet or coil Appliances Machine guards Often coated, ready for use Eg. roofing material
What material section would you use for General flame/laser/water cut parts
Flat Plate (Black)
General flame/laser/water cut parts
Plate fabricated machinery
Ship building
What material section would you use for General engineering applications
Flat Bar (Black or Bright),Hot and Cold rolled
What are the general types of bar
Round Bar (Black and Bright) General machine shop parts Shafts Available in a range of strengths Hollow Bar (Mostly Black) Much heavier wall than pipe Machine shop parts Reduces machining time and wastage
What does ERW stand for? (Seam welded thin wall tube)
Electric Resistance Welded Used in Exhaust pipe Light equipment Low pressure plumbing Moderate twisting and low bending strength
Note ERW = Seam welded pipe Heavier wall than tube Moderate pressure plumbing Galvanised water pipe Farm gates Good twisting and bending strength
What type of pipe would you use for boilers?
Seamless tube High pressure equipment Steam boilers Chemical equipment Good twisting and bending strength No seam for particle retention
What is a RHS section?
(Rectangular Hollow Section) Generally seam welded General machine or frame construction Easy to work with and weld cleanly Light wall (1.5mm) or heavy wall (6mm) Moderate twisting and good bending strength High buckling strength Consider how to weld together
What is a disadvantage of Angle sectoiin?
Poor twisting and bending strength.
Easily buckles.
but it is Easy to work with
Either equal or unequal length flange
What Standard Engineering Material Section is mostly used for construction
I Beam, Universal Beam Mostly used for construction Occasionally used for machines Excellent bending strength Poor for twisting Variation used for columns
Channel is also used as General structural section
Poor for buckling
What steel is trying to be something else?
Silver Steel
Not made from silver!
Centreless ground
Bright and almost polished mirror finish
Very high strength steel
Normally used in tool rooms
Can be hardened by various processes
Often flame hardened in the workshop
Diameter is ground to a moderate tolerance
Sometimes used for low cycle custom made punches, knives,
drills etc
What steel is used for Most drills, taps and dies
Custom ground lathe tools
High Speed Steel
Very hard
Can retain hardness at high temperature
Cannot be cut or shaped with conventional cutting tools
Normally ground to shape
Often supplied with a ground finish and in various sections
What material is used for hydraulic and pneumatic rams
Hard Chrome Bar Steel bar with hard chrome plating Use for hydraulic and pneumatic rams Also used with linear bearings Precision ground and polished surface Sometimes used for non-corrosive propertie
What type of copper tube is mostly used for domestic plumbing
Hard Copper Tube
Bought as straight tube
Difficult to make tight bends
For tight bends use weld fittings
What type of copper tube is Often used in refrigeration equipment
Annealed Copper Tube Generally small diameter Very flexible Bought coiled Good for custom bending Difficult to make look tidy
Which of the following is not a common thread locking system: a) Castle nut and cotter pin b) Tab washer c) Nylock nut d) Grub screw
Grub screw
A critical machine requires high tensile bolts, how do you know the bolt quality?: a) Numbers stamped into the head b) Letters stamped into the head c) Letters forged onto the head d) Numbers forged onto the head
Numbers forged onto the head
A torque wrench is used to:
a) Ensure the bolt is not over tightened
b) To reach nuts in difficult locations
c) Activate thread locking nuts
d) Measure the angle of rotation of the nut
Ensure the bolt is not over tightened
Which of the following is a reason not to select a bolted joint?: a) Non permanent fixture b) Joint may come slack due to vibration c) Dowels are required for alignment d) Use of unskilled labour
Joint may come slack due to vibration
What are 3 permanent joining methods?
Rivet
Weld
Glue
What are 3 Temporary (or Permanent) joining methods?
Screwed
Bolted
Spring
Magnet
Do you know your standard bolt terminology
thread, shank head, nominal length is the length without the head
Whats the difference between a bolt, thread and stud?
Bolt Tightened by turning the nut Screw Tightened by turning the head Stud Permanently screwed into a body and tightened by turning the nut
How does a bolt work to hold the pieces together
Bolt Pre-Load / Stretch Load / Stretch
When the bolt is tightened it stretches
like a spring…A very stiff spring
This puts tension in the bolt and
compression in the joint
Pre-tension (Pre-Load)
Needed to avoid material separation
Movement between the plates is dependant
on the bolt tension and the coefficient of
friction
Bolt/stud/screw stretches to cause pre-tension
Pre- Load Must Always Be > External Load
What are some common modes of failure for bolts/screws
Stripped Thread…Excess Axial Load
Miss-aligned Thread
Use Dowels to Avoid
Miss-alignment
How can you ensure the Correct Pre-Load is applied
Measuring Nut Angle Rotation
Measuring Bolt Stretch
Norbar Torque wrenches and equipment
Sheet metal for domestic appliances is:
a) Left in a hot rolled state
b) Painted before folding
c) Requires sand blasting before painting
d) An alloy of copper and iron
e) Prone to corrosion and must be handled
with care
b) Painted before folding
Two places left hand threads are used
flammable gas bottles
shade cloth thingy
Printng - FDM
UNI OWNED
Fused Deposition Modeling
Like a hot glue gun
1 or 2 nozzles
Why do some machines use Square ACME Threads
Strength, for things like lathes and vices
Printing - Polyjet
Similar to inkjet printer Droplets squirted from printer head UV light cures it Fine details Elastomer Multiple materials at once Various types of supports and removal
Printing - SLS/SLM
Selective laser sintering
Selective laser melting
Metals and plastics
Powder lay down in small thicknesses
Laser/electron beam fuses material
3D Printing
Powder is laid down
Inkjet printer head squirts ink type binding fluid
Low Strength
Full colour
How do snap fits work?
Parts Elastically Deform During Assembly
Can Be Permanent or Not
Typical Application is Joining Wire Connectors
Scanner - how do Structured light -White or blue light work
UNI OWNED
Project a series of linear patterns
Also uses triangulation to calculate distances
Uses the edge of the each line pattern
High resolution scanning is used for
Small parts
What are the Two Categories of Welding Processes
Fusion welding - coalescence is
accomplished by melting the two parts to
be joined, in some cases adding filler
metal to the joint
Examples: arc welding, resistance spot
welding, oxyfuel gas welding
Solid state welding - heat and/or pressure
are used to achieve coalescence, but no
melting of base metals occurs and no filler
metal is added
Examples: Forge welding, diffusion
welding.
Turntable scanning works by
Fixed scanner
Moving part
Why is it important to protect the weld pool
The molten weld pool is extremely reactive
with oxygen
The pool must be protected from the
atmosphere until the pool has solidified
Common Methods
Flux… forms a slag over the pool, requires an
extra operation to remove the slag
Gas as cover, extra cost of the inert gas but it is
a clean process
What is the 3D Scanning process
Scan the part Align scans Fusion, smoothing, editing - .STL file add texture if needed Use an external program to generate feature tree
How are overhanging features made with 3D printing
Removable support material
What is the 3D Scanning process
Scan the part Align scans Fusion, smoothing, editing - .STL file add texture if needed Use an external program to generate feature tree
How are overhanging features made with 3D printing
Removable support material
What are the advantages and disadvantages of Rivets
Advantages High Production Rates Simple Reliable Low Cost Blind Application (Pop) Permanent Disadvantages Requires impact or other loading to perform the application
What is a Hot (UpSet) Rivets
Hot rivet shrinks when it cools and adds extra compression in the joint Rivet diameter is increased to fill hole gap
2.5 million hot formed rivets holding the
Eiffel Tower together
What is an eyelet used for?
Used to provide strength for connection to a weak
material.
Often used to strengthen fabric for rope connections
How do snap fits work?
Parts Elastically Deform During Assembly
Can Be Permanent or Not
Typical Application is Joining Wire Connectors
Advantages of Powder Metallurgy
Specific porosity
Mass produce to near net shape
Favorable to casting
Can be automated
Disadvantages of Powder Metallurgy
High tooling and equipment costs Metallic powders are expensive Variation in density can occur Limited geometry Can not fill die laterally
Why do you blend particles for Powder Metallurgy
Particles with the same chemistry and different particle size
Reduces porosity
Why do you mix particles for Powder Metallurgy
particles with different chemistry
Makes alloys
What is the Powder Metallurgy process
Blend/mix
compaction
Sintering
deburing
Powder Metallurgy - Compaction
Punch-and-die
Powder fills die
Pressed at high pressures into shape with an axial punch
High pressure = high density = stronger
In compressed state the component is weak called a ‘Green Compact’
Powder Metallurgy - Sintering
Performed below melting temperature Increases strength and hardness Lubricant is burnt Particles fuse /Grain growth Metal stabilise
Part is approx 80% of the strength of a metal
How are powders created for Powder Metallurgy
Atomization
Chemical
Electrolytic
what are the Five Types of Welds
Surface Groove Fillet Plug Slot
How do you increase the strength of a powder metallurgy part?
Add a second metal which is absorbed in the furnace
Increases strength by increasing density
What are theTwo Categories of Welding Processes
Fusion welding - coalescence is
accomplished by melting the two parts to
be joined, in some cases adding filler
metal to the joint
Examples: arc welding, resistance spot
welding, oxyfuel gas welding
Solid state welding - heat and/or pressure
are used to achieve coalescence, but no
melting of base metals occurs and no filler
metal is added
Examples: Forge welding, diffusion
welding.
Sheet metal forming
Bending
Deep/cup drawing
shearing
miscellaneous
Why is it important to protect the weld pool
The molten weld pool is extremely reactive
with oxygen
The pool must be protected from the
atmosphere until the pool has solidified
Common Methods
Flux… forms a slag over the pool, requires an
extra operation to remove the slag
Gas as cover, extra cost of the inert gas but it is
a clean process
Powder Metallurgy - Powder is composed of
Combination of metal powders and lubricants
Metals: Carbon, Steel, etc
How do you increase the strength of a powder metallurgy part?
Add a second metal which is absorbed in the furnace
Increases strength by increasing density
Bulk formatting deformation/forming
Rolling
Forging
Extrusion
Wire and bar drawing
Sheet metal forming
Bending
Deep/cup drawing
shearing
miscellaneous
Bulk deformation advantages
Significant shape change
Material strength can be increased during cold forming
Near net shape
Sometimes parts don’t require subsequent machining
Bulk deformation
Deforming parts whose initial form is bulk rather than sheet
Starts with cylindrical/rectangular bars and billets
The process causes plastic deformation
Performed hot or cold
Define: Rolling
plate is squeezed between rollers to reduce thickness
Rollers oppose each other
Compressive forces
Friction pulls the sheet though
Define: Forging
The work piece is squeezed between opposing dies or hammered into shape
Define: Extrusion
The work material is squeezed
through a die
Define: Wire and bar drawing
the diameter of wire or bar stock is reduced by pulling the material through a die opening
Bulk starting shape: Bloom
Large square/rectangle bar
Bulk starting shape: Slab
Thick plate
Bulk starting shape: Billet
Small bar
what is PAW welding
Plasma Arc Welding
Special form of fusion welding
in which a constricted plasma
arc is directed at the weld
area. >20,000 deg
Advantages: Good arc stability and excellent weld quality Better penetration control than other AW processes High travel speeds Can be used to weld almost any metals Disadvantages: High equipment cost Larger torch size than other AW processes Tends to restrict access in some joints Application of PAW Automobile assemblies Appliance manufacture Metal cabinets
Hot rolling
‘black’ finish - due to oxidation
Large deformation
Less force required
Grains reform
What is the definition of Solid State
Welding Processes
Operation done with little/no
melting of the material.
SSW Advantages over Fusion
Welding Processes
If no melting, then no heat affected zone, so metal
around joint, in some cases, retains original
properties
Many SSW processes produce welded joints that
bond the entire contact interface between two
parts rather than at distinct spots or seams
Some SSW processes can be used to bond
dissimilar metals, without concerns about relative
melting points, thermal expansions, and other
problems that arise in Fusion Welding
Can Friction Welding (FRW) be used to join dissimilar metals
fuck yeah
What joining technique would you use for making 20 boat trailers? a) Stick b) MIG (Metal Inert Gas) c) TIG (Tungsten Inert Gas) d) Bolts and Rivets
b) MIG (Metal Inert Gas)
Riveted joints offer the following advantages a) Fast b) Reliable c) Non skilled labour d) Tight joint e) All of the above
e, All of the above
Left hand threads are identified by?
a) Stamp on the nut
b) Forging on the bolt head
c) Groove around the nut or bolt head
d) Tapered thread
c) Groove around the nut or bolt head
Left hand threads are most commonly used for? a) Oxygen bottle pipe connections b) Tightening ropes c) Engine cylinder head studs d) Cap screws
b) Tightening ropes (turn buckle)
Cold rolling
‘bright’ finish
produces better surface finish and more accurate size than cold rolling
Grain elongate - better material properties
Hot rolling
‘black’ finish - due to oxidation
Large deformation
Less force required
Grains reform
Roller configuration: Two
High velocity
What is the purpose of support rollers
Heavy backing gives support
Less unwanted deformation
Reflow Soldering is primarily used for?
a) Plumbing… spouting
b) Plumbing… house water pipes
c) Surface mounted electronic boards
d) Through hole electronics boards
c) Surface mounted electronic boards
Rolling configuration: Tandom
Each set performs further deformation
Rotational speed of each roller set much be higher than the previous
Thread rolling
Rolled against a die
Generally done cold
Better thread strength and surface than machining
Brazing filler can be supplied as?
a) Foil
b) Paste
c) Rod
d) All of the above
d) All of the above
For using adhesives on a production line which of the following is an important consideration: a) Curing time b) Clamping method c) Materials to bond d) Surface roughness e) All of the above
e) All of the above
Tolerance…
The difference between the maximum and minimum limits of size is the tolerance
Fits…
When two parts are assembled the relation resulting from the difference between their sizes before assembly is called a fit. (fitting - the ability to be assembled)
35H7 What does 35, H and the 7 refer to?
35 - Basic size
H - Fundamental deviation for hole
7 - IT grade for hole
A sheet metal part is to be permanently attached to a metal RHS frame with a fastener. There is no rear access. Which of the following could work? a) Hex head nut and bolt b) Pop rivet c) Upset rivet d) Pressed clinch
b) Pop rivet
Which of the following should you consider when welding together two parts? a) Distortion b) HAZ c) Filler rod compatibility d) Potential damage to local parts e) All of the above
e) All of the above
remember HAZ means heat affected zone
You need to make a special shaped form tool for turning low strength metal. What material would you use? a) Commercial bright b) Hard chrome rod c) Silver steel d) High speed steel e) All of the above
d) High speed steel
A bolted joint is required that must be easy to undo without tools. What could you use? a) Castle nut b) Flange nut c) Nylock nut d) Wing nut e) Cap nut
d) Wing nut
A sheet metal part is to be permanently attached to a metal RHS frame with a fastener. There is no rear access. Which of the following could work? a) Hex head nut and bolt b) Pop rivet c) Upset rivet d) Pressed clinch
b) Pop rivet
Rolling configuration: Cluster
Allows for small rolls
Less force and power
Multiple support rollers
Thread rolling
Forging - Generally done cold
Better thread strength and surface than machining
Rolling configuration: Tandom
Each set performs further deformation
Rotational speed of each roller set much be higher than the previous
What is ring rolling used for
Ball bearing races
Heavy rotating machinery
Pressure vessels
What is the minimum clearance if George’s penis had a diameter of 20: 18 - 22 mm and the poor girls
hole is 23: 22 - 24? What type of fit is this?
Allowance: 1 mm
Clearance fit. Praise the lord. It’s a good thing this George has a small penis
why are Lubricants needed for Hot Forging/sex
Lubricant is required to stop sticking, should be
sliding motion.
Applications of forging
Crankshafts for engines
Connecting rods for engines
Aircraft structural parts
Spanners
What is the difference between forward and backward extrusion
Direct (Forward) Extrusion - Starting billet round; final shape determined by the die (like toothpaste)
Indirect (Backward/Reverse) Extrusion, you basically ram it in
Forge hammer
applies impact load. Hammer is lifted then dropped
Upset forging (heading)
Open die - between two dies
Used to form heads on screw, bolts, etc
Impression-die Forming
The die has a cavity. The metal is constrained but a
flash is formed.
Flash cools quicker
Flash is removed by
Trimming
grinding
sawing
What does ANSI (ASME) stand for
American National Standards Institute
GD&T
Geometric dimensioning and tolerancing.
Maximum material condition MMC explain for shaft and hole
The MMC is the size of the part when it consists of the most material. For a shaft the is the largest diameter. For a hole this is the smallest diameter
Clearance fit
There is always space: Min clearance > 0
Interference fit
There is never a space: Min Clearance =
Transition fit
Could be clearance or interference.
Max clearance > 0
Min clearance
Define the type of fit that a mattress wank creates
Interference
What is the minimum clearance if George’s penis had a diameter of 20: 18 - 22 mm and the poor girls
hole is 23: 22 - 24? What type of fit is this?
Allowance: 1 mm
Clearance fit. Praise the lord. It’s a good thing this George has a small penis
What is the definition of Extrusion
Compression forming process in which the work
metal is forced to flow through a die opening to produce a
desired cross-sectional shape
Like squeezing toothpaste
What is the difference between forward and backward extrusion
Direct (Forward) Extrusion - Starting billet round; final shape determined by the die (like toothpaste)
Indirect (Backward/Reverse) Extrusion, you basically ram it in
Importance of machining
Variety of work materials can be machined
Most frequently used to cut metals
Rapid material removal
Variety of part shapes and special geometric
features possible, such as:
Screw threads
Accurate round holes
Very straight edges and surfaces
Good? dimensional accuracy and surface finish
Disadvantages of machining
Wasteful of material
-Chips generated in machining are wasted material
Time consuming
-A machining operation sometimes takes more time
to shape a given part than alternative shaping
processes, such as casting, powder metallurgy, or
forming
Types of machining chips
- Discontinuous chip
- Continuous chip
- Continuous chip with Built-up Edge (BUE)
- Serrated chip
Do Extrusions leave the die straight?
no (rarely) to do this you should Stretch or Roll piece
What are 3 Defects in Extruded Products
Centre burst (chevron cracking)
· internal crack develops from tensile stresses along
centreline
b)Piping (fishtailing)
· sink hole that develops during direct extrusion
c)Surface cracking
· caused by high work part surface temperatures and
high extrusion speeds
What is the Wire and Bar Drawing definition
Cross-section of a bar, rod, or wire is
reduced by pulling it through a die opening
ó Tension and compression stress applied to
squeeze metal
